Race Car

Hayos Racing

Hayos Racing has been running a Toyota Truck in various configurations for many years.
Curt and Patty Hayos

They have won several regional championships and gained considerable respect for fair and even handed competition. Their teams history can be followed at Hayos Motor sports I started helping their team with technical questions in 2003 regarding their 22 R based race engine and some tuning issues. That lead to further involvement until in 2006 the truck was switched to a V-6 engine based off a 5V-FE Toyota product converted to racing use by a prominent north Bay Area shop. That engine was rebuilt in my shop to reverse engineer it's secrets, document it's parts list, and prove it's horsepower. It was later dyno tuned in Fremont CA to re-set up the fuel injection management system. That engine powered the truck at the Terrible Herbst SCORE race in 2007 where their team ran in 4th place until overturning on a triple jump which accident injured Patty Hayos the trucks driver.

Hayos truck final prep.

She has recovered and the truck is being rebuilt for the 2008 season.

Part of that effort is overhauling the 5V-FE engine again because it sustained minor damage from running upside down. That was done in my shop and installation was done at the Hayos Racing facility. It is presently being run for testing and practice on a track in the Prairie City Off Road Park in central California. Several additional Toyota engines have been obtained for modification and development at Fowler Automotive because this platform has a lot of room to make more power. At least two more chassis are being built by the Hayos team and the teams future looks promising.

Vintage Mini Cooper race car & Ladd Fowler engine and car builder biographic sketch

Greg Jones
Managing Editor, Engine Builder<http://www.enginebuildermag.com/>
gjones@babcox.com<mailto:gjones@babcox.com>
(330) 670-1234 x272

3550 Embassy Parkway
Akron, OH 44333

Good evening Greg, I’ll put my response to your questions in blue. I’ve metaphorically tossed you a majority of whole baby’s story, including its blanket and buggy. Ladd

* Can you give me some background information about yourself? How did you get into the industry/engine building?

I’ve been a mechanic since I was very young, 7-8 years old. Back then my dad gave me a go kart fitted for a Briggs & Stratton lawn mower engine which I had to swap on and off his mover to ride the kart. I always had access to his hand tools to make things and a few years later when I was 12 he gave me a set of welding torches. That led real fast to building two stroke mini bikes running McCulloch engines which were flat out dangerous – I’d chase down DT1 Yamaha motorcycles in the Santa Cruz Mountains pretty successfully. I’d heard a story that the mark of a true master mechanic was being able to do things blindfolded so I taught myself how to build the McCulloch 91 – 101 engines blindfolded when I was a freshman in High School. I also rebuilt every one of our family car engines with my Dad – Buicks and Cadillacs - between late grade school to college years.

By then my older buddies and I had motorcycles and cars which we worked on after school when we didn’t have jobs to attend to. By the end of my junior year I was maintaining a dairy processing plant three days a week because I was nearly the only one at that business who (intuitively) understood their pasteurizing and bottling equipment. Eventually I became one of the youngest licensed processing plant operators in the state, getting my license at age 18 under the tutelage of a state inspector. And a few afternoons a week I worked for a lumber and supply company fixing trucks. I was also fixing cars for people who somehow found out I could do that when I was not working elsewhere.

This gave me a chance to know our local auto parts supplier well. They had a machine shop in back of the store which fascinated me because I had constant need for industrial and automotive parts and machine made or repaired pieces. Somehow I graduated High School as a “C” student. Looking back that is amazing because I never did any homework or read assignments. I also missed many classes when called in to work early.

In my senior year one of my buddies had a neighbor who was racing Mini Cooper “S” cars and Corvettes in SCCA autocross events with some success. He bought a Mini Cooper to repair to be like his neighbor. Occasionally I helped my buddy convert it to “S” specification by swapping performance parts into it. Because I was the guy who had a torch set we used that to heat-then-beat his firewall in for carburetor clearance. It was the first car I ever caught on fire. We put most of the fire out pretty quickly, but it continued smoldering for hours under the dashboard.

I had bought a ’65 Pontiac GTO by then because my mother forbid me to buy a Corvette saying they were too dangerous. Looking back that was actually a pretty funny turning point. The GTO didn’t stop, couldn’t turn, and had more power than many Corvettes. It was the more dangerous car which shortcomings I initially proceeded to amplify, not understanding even more power would make it handle worse faster. Some other friends were autocrossing a Boss 302 Mustang with OEM support, various Corvettes, and Z-28 Camaros so I tagged along with my GTO. I believe I was 7^th in the county one year running in the SCCA “H production modified” class, about a second behind the Camaros and 2 seconds behind the Corvettes. I was rebuilding my Pontiac’s engine almost monthly because I couldn’t get good timing chains. And I didn’t understand valve train geometry that changed because of various cylinder head swaps until a bit later on. When Cloyes came out with double roller chain models and some hot rod magazine did an article about checking valve to rocker arm contact points my engines started to run better and longer. I also began to learn about chassis set up trying to make that GTO corner like a Corvette.

But my buddy and I drifted apart after High School so I didn’t work on a Mini Cooper again until a couple of years ago. I mostly worked with other vehicles, some of which became known as “muscle cars”, and repairing machinery and equipment.

In 1972 I started what eventually became my small automotive repair business. And I continued to seek out opportunities to gain further education to validate what I was attempting to do.

I attended Foothill College majoring in business administration but that was very hard for me. The scale of business size discussed in class started with a few hundred employees but I wanted to learn about proprietorships and partnerships with a few guys. After two years of agony I switched to De Anza College majoring in their auto technology program, then graduated 2nd in my class. At graduation I was recruited by the auto parts store I was doing business with to be a machinist in their 3 man back room shop. After a year the business owner opened a second location and I was offered that stores machine shop as a solo gig. But I quit on good terms despite my love for machining to go east for what became an office job running finances and managing a fleet of 65 cars scattered throughout the New England States. After a couple of years of freezing winters and shocking eye opening experiences with rusted out near new cars I came back to sunny California to more formally open “Fowler Automotive” in 1976. It was an easy economic decision despite being asked to return to work by business owners of every job I’d ever held. I could make in a day in my own shop what took a week to earn as an employee. So I serviced those businesses as an independent contractor while gaining a few more dedicated clients whose families I served, in some cases, for three generations before I retired a couple of years ago.

* Can you give me some background about Fowler Automotive? When did it start? What does the shop specialize in? Do you work on an assortment of engines and applications? Is it a full machine shop? Do you do everything in-house?

Fowler Automotive has been a sole proprietorship since 1977. It was formed as a home based service business with a somewhat backwards business plan. I have done a very broad variety of automotive and equipment related services for a small select client group for the last forty-five years. For their various needs and interests I’ve cared for everything from small rototillers to long haul diesel trucks with a few boats, motorhomes, and an airplane tossed in. Some of that work was strictly economic business - to get something working again so it could generate profits. Some has been recreational to enable their various trips, movie shoots, or competition / restoration projects. And a majority of it was in-between those categories where I was providing ordinary repair service for their family vehicles. Over those years I accumulated equipment and tools to meet their needs as I went along.

Along that path I’ve been invited to and attended GM school, Ford Industrial Engine School and countless clinics or manufactures training sessions. I sought out an opportunity to attend Cummins Engine School. I went back to college at night to formally learn welding skills and non-destructive testing processes.

I was lucky to trade Joe Mondello an intake manifold resurfacing fixture I invented then patented for attendance at his engine and head porting schools. Bill Jones of Taylorsville Utah took time from his life to teach me a lot about head porting and air flow from a practical perspective. I’ve been tutored by Allan Lockheed and Dema Elgin in advanced engine design and competition engine preparation over many years’ time. I’ve had significant passing acquaintance with several really great leaders in fields of business ethics and industry procedures who mentored me as I helped them. I was among the first technicians to be tested and awarded ASE “Master Mechanic” and “Master Machinist” certificates. I kept both those ratings current until a couple of years ago. Becoming and staying educated in my industry is central to the success I’ve had meeting a diverse range of client requirements.

In the 1980’s I was doing a lot of Corvette repair and service as Fowler Automotive in conjunction with another friend’s business; Herlinger Corvette Repair. I also ran an entry level stock car under NASCAR rules in the Winston West series. I did well as an owner / rooky driver finishing tenth place out of over 250 cars registered to run in the area. But I didn’t have time to build my own engines despite having education and training to do that. So I hired it out. When my engine builder became ill with cancer I bought his home and automotive machine shop to enable continuing service for my clients, and then helped care for him until his passing. After his passing I sold my stock car then sponsored out of that machine shop, over the next twenty years in small ways, TrueSpec Racing who ran Chevrolet engines in various dirt track venues, Pennington #9 Racing who ran Ford Clevor engines in IMCA modified events, and Hayos Motorsports, an off road truck team running Toyota engines.

I have used a simple rule of thumb for business equipment acquisition. If it will pay for itself in a few jobs I’ll acquire it or establish a working relationship to use it. I have come to understand a business principal – you don’t need to own everything for a “full shop” but you do need to have knowledge of where and how all those machines work and how to gain essentially immediate access to them when needed. A growing problem which now confronts service providers like me is many of our vendors and affiliated shops are closing so their inventory and equipment disappears which makes it far harder to actually create new automotive race cars, hot rods, or restore vintage vehicles.

A bit more than a decade ago I was diagnosed with leukemia and have been in and out of experimental chemotherapy since. A few years ago my automotive vehicle / fabrication shop was zoned out of existence after being in that location for more than 35 years. But I was able to keep my automotive machine shop which was in the next town, mostly for hobby shop interests. I still own a lot of metal fabrication equipment and traditional industrial machine tools, most of which have gone into “semi-storage” circumstances.

As Fowler Automotive I have been “the kid” in a circle of older car guys who owned businesses I ran with. Many of whom were far more talented than I. Many of them have passed on. I am now semi-retired and specialize in doing fun things with my remaining clients, who have become friends and buddies. We do projects; like building this Mini Cooper to win the Nationals. For us, fun projects seem to attract more fun projects so we are considering getting another building, to both gather our collective equipment into one place and consolidate more of our labor into one spot. But the financial implications of doing that in the Silicon Valley simply don’t make sense. So we may fade away like so many other shops have done.

* Layand Engine – How did the engine get to the shop, is this from a repeat customer or new customer?

This British Leyland engine came into my shop from a client I’d built a 1966 Mustang for. His wife wanted a V-8 automatic transmission light blue with white interior Pony Pack convertible. I built them one from a brown on brown car that sat oddly and too high, which turned out to be full of hidden body damage. I saved the front clip, cowl, floors, and trunk lid to build them a car from that, in cooperation with a body shop. When he wanted to go racing he bought a Mini Cooper to relive and extend his college experiences driving that marque from days when they were new. Because he was so pleased how that Mustang turned out I was invited to straighten out the Mini Cooper after he had some bad experiences in other specialty shops.
* What was wrong with the engine/reason it was there?

Holger & Ladd at winners podium Thunderhill

This Mini Cooper was a beautiful show car semi-converted to be an autocross play car. After being purchased by my client we took it to Thunderhill Race Track in Northern California for an open track test day with other clients of mine who were running their cars. It drove ok and showed promise of becoming really fun. It was the first Mini I ever drove. He decided to send his Mini to two nationally prominent Mini Cooper shops for “road race” preparation and various upgrades.

Then the car owner took it to Sonoma Raceway for an event after spending many thousands of dollars where he experienced multiple significant vehicle failures. He called me to the track so I could trouble shoot his vehicle where I found issues with ignition, carburetion, charging, cooling, and engine valve train interference. There were also fluid leaks, and generally poor assembly which taken all together prevented his Mini Cooper from making an entire lap under its own power.

I fixed what I could in the Pits with generous help from other racers in his class – remember; I’d not worked on a Mini Cooper since high school – almost 50 years previous – so I had to take a moment with a knee on the ground with it, so to speak, then another moment to get my brain to see what my eyes were looking at. I was able to get his car to run a couple of places in front of being last by the end of his event program.

The car was returned to the building shops for “warranty service” where it was fitted with a new transmission, more engine upgrades, swapped its Weber carburetion set up for SU’s, received an alternator, and so on. He felt confused by this, especially when it broke the new transmission on his next outing vs. the turnaround he had seen under my care. So I was hired to fix the car and act as crew chief for his next season, after it was again returned to the other shops for a replacement transmission.

Because the Mini Cooper engine crankcase also houses the transmission and differential while sharing a common oil system it is very hard to talk about just the engine, because, if some part of that system fails it usually wipes out everything else too. Pictured is my client’s crankcase assembly ready to receive his modified race engine.

Holger trans tappets push rod work 010

Because the Mini Cooper driveline is so short and suspension so closely coupled, any suspension or driveline vibration or failure can affect the final drive inside the engine crankcase, which can then damage the engine.

* What application is the engine for? Does the Mini Cooper get raced, or was this just for a restoration project?

This Mini Cooper project started out as a vintage road race effort on a “hobby” basis. After a couple of events I had his car running mid pack, about 6 seconds off the leaders at Sonoma and Laguna Seca tracks.

Holger #41 in Mini Cooper run group Sonoma

This is a dangerous position to be in because other cars can hit you when you are in the middle of things. We were discussing improvements to his car which would allow it to move into running with more capable cars and drivers when he was lightly kissed by another car whose driver turned right in a left hand corner rubbing our Mini Cooper in its left rear fender arch. Our damage was near zero, 10 seconds with buffing wax took the rub mark off and a washer under the screw head of the Mini’s plastic wheel arch molding fixed that. However, in my opinion, the driver who caused contact between the cars complained so effectively about “over aggressive driving” he got my client and himself suspended for a year. We were shocked at the ruling, but within a couple of months figured we’d use that time to rebuild the Mini Cooper correcting fundamental issues and making upgrades. It was a turning point away from “restoration” towards “race car”.

* What kind of work did you have to do on the engine? Machine work to the block or other parts? Other adjustments, etc.?

To gain 6 seconds lap time vs. the leaders we deliberately analyzed options open to us within class rules and known parts we could buy. Modifications were planned by study of “A+” series engine existing art and published articles, then by my client’s sense as a driver of what he needed to go faster. The engine rules for our vintage class dictated a non-roller rocker arm assembly be used and visually period correct appearance of the engine. We had to use SU carburetors and could not modify the engine compartment sheet metal (for more velocity stack clearance) past what was done on original “S” model vehicles.

In this case engine work started with another transmission gear set which had dog gear shifting pawls. We calculated a 2 second per lap gain was likely because of quicker shifting speed and having better ratio selections. We also felt replacement of the differential with a Quaff torque biasing unit would extend engine and tire life. Conventional traction lock and posi-traction clutching differentials shed materials into their oil supply, which in this engine are then fed into the engine bearings. We had excessive wheel spin in corners that was melting our tires which we felt could be better controlled.

Holger Transmission and rear end shimming 003

Opening the crankcase for gear replacement would lead to inspection of the engine’s condition, which had excessive pressure indicating poor ring sealing.

Replacement of the gear sets would also allow replacement of both axle assemblies with lighter, stronger, smoother running shafts thereby increasing power available to the wheels, and reliability. In my opinion running stock Mini Cooper drive shafts above 90 mph is insane. A broken driveshaft might strike the oil sump knocking a hole which will cause engine failure, a fire, and perhaps a wreck. Our Mini needed to exceed 110 mph to win; therefore we needed upgraded drive shafts.

Swiftune provided 10 spline Hardy joints from Spicer with shafts and yokes to match. But they were not shipped with a grease seal and packing nut despite having a grease nipple for lubrication. If installed as shipped they would toss grease directly onto the headers causing a fire hazard. Swiftune, when called, said “nobody runs the grease seal or nut so we don’t send them out that way”. And then said they could not supply them. Our local Spicer dealer could sell us new (identical) yokes with the seal and nut preinstalled so we bought them, robbed their seals onto the Swiftune parts, and saved the extra forged sections for spare parts.

There was a second minor issue with Swiftune supplied output flanges. The Quaff differential, on the RH side, would not allow its flange to seat fully into the differential where a snap ring would retain it. This was not discovered until the car was pitted after qualifying laps in the 2017 Canadian / American Challenge race weekend. The yoke had walked out of the case introducing a vibration into the driveline. A quick trackside fix was to put a hose clamp on the axle which retained the yoke. A permanent solution done later on was to machine about .075 off the yoke which allowed it to seat fully.

Oil channel work and driveshafts 010

To gain more seconds on leading cars my client’s engine would have to rev higher. Virtually all Mini Coopers that road race in various divisions of vintage stock class use one size of Hoosier tire. It is the only one available. To gain top speed, and because final drive ratios are essentially limited to the one you build an engine with, the engine itself needed modification to run faster. Virtually all historical wisdom, and both professional Mini building shops in our area indicated limiting RPM to under 6500 - 7000 would delay crankshaft failure for a season or more vs. failure within a couple of events if run faster. To run “up front” we needed to increase engine speed above 8000 RPM which meant engineering for 9000 RPM to create some safety for over-speeding incidents. To gain that increase in engine speed virtually every part of the engine needed modification, including the induction and exhaust systems.

* What parts did you use in the engine? Please let me know the specific part and manufacturer – block, cylinder heads, rods, pistons, crank, camshaft, bearings, gaskets, valve train, etc. Do you prefer a certain brand of oil?

Despite having a new OEM crankshaft in an “A+” series block running new upgraded rods and pistons we retired those parts in favor of a dedicated DC5-2 racing lightweight rotating assembly from Swiftune in Europe. They recommend against using a harmonic damper, which in my opinion is utter foolishness. We used a Fortech FOR098 racing damper. We also bought Swiftune’s “Feather Light” lightweight clutch, upgraded drop gears, pistons, bearings, double row timing chain, and electronic distributor assemblies. I believe they also marketed the dog gear transmission kit and differential by Quaff. We had a “Longman” C-AHT221 cylinder head, fully worked to current racing configuration, but determined we needed to retire it also, in favor of one ported a bit differently. I made a new head based off casting #12G940. We bought a Swiftune camshaft and tappet set with cam bearings to suit our intended road racing use. Virtually all smaller parts like thrust washers, fasteners, and gaskets came from Mini Mania and Seven Mini Parts. All three companies, as vendors, are quite good at having everything needed in stock for immediate shipment.

Computer modeling software from Rapid Line and Performance Trends was used to influence many aspects of our decision making. I’ve used both programs for many years and upgraded both for this project to their newest “Pro” versions.

I made an informal poll of most Mini Cooper owners at a couple of events we attended in 2016 regarding engine oil. Most teams were running Redline 50w synthetic oil without any problems at between 75 to 90 psi. At that time we were also, which I felt was an area for some testing and possible improvement.

* Did you hit any road blocks with this build, or did it go together fairly smoothly?

Our troubles started with this build almost immediately. Nearly every engine part and subassembly needed rework help except the actual crankshaft and rods. By contrast the transmission and final drive kits were straight forward and nearly flawless. In the transmission only reverse gear needed a small bit of “grinding love” with an abrasive wheel and a couple of thin shims to assure clean disengagement.

Beginning with the premise of “trust nothing and nobody” I sent the Swiftune #SW2307 camshaft to Elgin cams to be reverse engineered. While Swiftune provided some data about it, until any cam is fully profiled and checked you don’t really have sufficient data to computer model engine designs that may use it.

We discovered the camshaft provided was much closer to a hot street car / autocross design instead of the full on road race cam we requested. We also discovered 6cc dish pistons provided in the Swiftune kit would drop our compression ratio from mid-13’s typical for Mini Cooper racing engines probability into the low 11’s or mid-10 range, depending on what head we eventually used. That led to two decisions. First we’d live with a compression ratio loss by having a custom cam made which re-timed the intake valve closing. And second we would optimize a new camshaft design to current state of the art technology with air flow data from a fresh head build up. Instructions to Dema Elgin were eventually simple: “grind the tallest lobe you can, onto the best blank you can, to obtain the most aggressive timing that won’t roll off a Ford tappet”. He understood that perfectly having designed BMC cams for winning engines and other companies, or authors, for decades.

As I discussed this with a long time hot rod, race car, and engine building friend, Gary Hubback, we tumbled onto noticing the BMC bucket tappet (photo on right) looked a lot like a Ford Le Mans 427cid engine part Gary had bought from Hollman / Moody then run in his record holding drag car in the late 1960’s (in photo on Left). He still had most of an NOS set securely under his workbench which allowed us to take direct measurements vs. BMC tappets.

Holger Mini Cooper oversize tappet 001

We did Rockwell testing with Swiftune, Mini Mania, ATP (David Vizard’s old company), and Ford parts to determine which tappets would be the hardest (Ford). If we bored the BMC block tappet holes from .811 to suit the Ford .875 tappets Dema could put a more aggressive lobe onto a new BMC blank. Because of the way internal cam journal webs are cast in the block to support the cam, upsizing larger than .875 tappets would become very hard to do. And would require a custom “fatter” or welded up camshaft blank to gain any advantage in profile selection.

Boring BMC tappet holes required being able to reach nearly a foot into the block (from collet to tool tip) and machining a nearly blind hole at the correct 2 degree inboard inclination from the cylinder bore centerline. At the top of a BMC “A+” engine tappet bore is a hole about 3/8 inch in diameter intersecting an oil return galley within about a quarter inch. The pushrod passes upward through the hole and galley to the head inclined inboard to meet the rocker arm shaft, while oil returning from the head drips down into the tappet from the galley. Oil dripping down also fills each tappet bucket and seeps out of a hole in the side of the tappet body lubricating it. The pushrod is about 1/4 inch diameter, solid cast steel, and isn’t very strong or stable at higher loads or speeds. That whole system is very iffy in my opinion and needs modification for high speed operation. One modification made was adding a second tappet drain hole. Shown here the tappets have been anti friction coated and drilled. They are racked and ready to clean. At this point we had 11 candidate tappets remaining of which I chose the best 8 to install in this engine.

Holger Mini Cooper trans, tappets, pushrod

Once the engine is running each tappet gains about 30+ grams of oil weight which isn’t any good. Think of the camshaft load running 8 hydraulic pumps jetting oil back up the tappet bore into the drain galley through that small hole which is essentially plugged up by the pushrod.

I made tooling similar to a BHJ Lifter-Tru set, but suited to the BMC blind hole block. In the photo, starting on the left side, are two adaptor rings to locate a centering bar into cam bearing bores. In the central photo area is the centering round stock bar which has a hole pattern bored into it matching the blocks tappet holes. It locates two dowel pins into existing or re-bored tappet holes establishing a centerline and axes for machine work. In the photo, right of center are two dowel pins with different sized ends allowing all combinations of bored and un-bored tappet holes to be located. They jam in tappet holes, locking the bar into a correct position for the next hole to be machined. Photo lower center is a lock ring which bolts to the blocks front surface double locking the bar from any movement after the dowel pins are removed to insert cutting tooling. Finishing off the tool set, but not shown, is a precision drill and reamer. Also; for final sizing a custom lapping rod is used. It fits into the dowel pin centering holes in the locating bar which holds it very steady and at the correct position in the same collet used to oversize the tappet hole. I also made a special tappet which has a scribe point exactly in its center for marking a line in the camshaft blank verifying correct location.

BMC tappet borning guide parts 002

Then I re-bored the tappet holes entirely into the intersecting oil galley eliminating restriction possibly caused by pushrod and tappet pumping motions. I used my Serdi seat and guide machine to do the boring job because this 1275cc BMC block (bored to 1310cc) is so small you can treat it like a cylinder head in many fixturing considerations. Traversing the air float head of my Serdi machine in conjunction with my tooling is faster than setting up then moving a milling machine table. Chip removal from the nearly blind hole while machining was done by vacuum suction out the little oil galley hole. If chips are allowed to rise up the drill’s helix they can scar a newly made tappet bore deeper than the reamer or hone can remove. This is a tricky bit of machine work, especially finish lapping to size and then honing. The tappets are select fit to their bores in final engine assembly.

tappet bore set up overview 005

And after drawing a blue print of the BMC block’s cam area “as made” I found its existing tappet bores were only approximately offset equally from cam lobe centerlines. This indicated non-rotating tappet issues might happen. I corrected my tooling to more accurately place each tappet against the cam lobe across the cams length with a proper offset to allow for rotation when ground to the appropriate taper.

Holger mini cooper cam and tappet work 004

BMC tappet boring guide parts 004

The next major challenge with the block is moving its pushrod holes inboard and oversizing them to 7/16th for tubular 5/16^th inch custom pushrods supplied by Smith Brothers. The hole needs to be moved, on its 2 degree inclination, measured at the top, about .080 or more over about a 6 inch depth. Shown in the photo below is an initial set up where pushrod holes are first drilled oversize to 7/16th. Then I made a tool change to a very long milling cutter which moved the hole over. The aluminum bar was a “straight edge” which located my tooling parallel to the crankshaft centerline while being angled inward from the cylinder centerline. Installing the drill upside down into the hole and collet helps better locate the Serdi machine air float head because my ground rod center finding tool was AWOL somewhere else in my shop that day.

holger mini cooper trans, tappets, pushrod work 024

This necessary machine work resulted in breaking into the water jacket on 3 of the 8 holes. Casting shift seemed to favor the front holes and thin out the rear ones. Fixing those perforations required drilling 3/4 inch holes in the blocks cylinder deck adjacent to the pushrod hole. Then sandblasting the water jacket to bare roughed up metal, forming thin sheet metal “patch plates” over the areas, then epoxy cementing them into place using wire spider legs to restrain movement over night while curing took place. Greased wooden dowel pins preserved the oversize pushrod hole from filling with excess epoxy. Then I had to plug the deck without creating a need to re-machine it. The existing compression height of block decking done in other shops had left no material for service repairs. Dressing off square drive pipe plugs was done with a hand file and large diamond lap stone after rough grinding the bulk of extra metal plug away.

Epoxy repair metal patch and guide wire

Epoxy patch in place close up

epoxy repair big overview

Holger engine gyptal application 002

The next block machining operation was dowel pinning the head to the block and correcting head stud engagement length. The head could move on the block’s ARP stud shoulders more than the thickness of its gasket fire ring (Mini Mania Turbo Metro gasket #STR1057) and could bring its oversized valves into possible contact with the block cylinder walls. Therefore to assure consistent assembly location 2 hollow dowel pins were installed around the end studs. The dowels were lathe turned from steel stock. The centering tool (photo left side) was made to fit onto a valve guide top trimming cutter. The cutter was repurposed to machine out counter bores to hold the dowels. Not shown is a sandwich die to allow the valve guide trimming cutter to enlarge two complementary head gasket stud holes so the head gasket, head, and block would all register together.

Holger air flow and head dowels 003

I found the head stud holes, after deck milling by the other machine shops, only had 5-7 threads remaining in the block so they needed to be deepened and re-tapped allowing an HSA11-B ARP stud kit to engage fully 8 threads deep. This was also the time to add a head stud hole to the new head. Passenger service BMC engines didn’t need a head bolt near the water outlet but racing Mini Coopers did. The BMC Factory added one stud to that area and it has become a standard operation to drill any head used for competition in the same location as the factory did. I did that by pattern drilling through a head that had the hole already in it. They simply needed to be stacked up, doweled together so they remained indexed while machined, and a long drill passed through.

pattern drill head stud holes

Enlargement to 1/4 inch of all oil passageways going to the head, including machining an oil transfer slot in the forward cam bearing and around the camshaft journal was done. Do not cut away the “dam” between an existing axial oil channel and new radial one. You want extra oil to go up to the head not out the front of the engine. Adding a couple of missing threaded holes which attach the oil pump body to the block was eventually done as well.

Oil channel work and driveshafts

With significant additions, remaining block preparations more or less followed David Visard’s book and standard race engine practice.

This is the set up I use to degree camshafts. One dial indicator resolving to .0001 is set up on a deck bridge to monitor TDC. A second dial is on the intake lobe pushrod resolving to .001 and a third indicator is on the exhaust lobe pushrod resolving to .001. That makes figuring out overlap timing very easy. You can just watch the dials and move pointed magnets on the timing wheel to stick on any degree location you want to count from. I have black magnets for intake and red for exhaust. Those basic tools came from PowerHouse (Comp Cams) many years ago and since then were extensively modified to become more versatile. The dial indicators came from Peacock and Mitutoyo. The front pulley supplied with our Swiftune DC5-2 crankshaft was re-machined to become a hub for holding the degree wheel.

Holger cam timing set up 001

Some additions were epoxy bonding into the engine sump 4 large super magnets below the transmission gears in the path of a Mini Mania #C-AHT54 racing oil pickup.

Transmission magnets 001

I used their upgraded water pump #GWP-187EVO with the largest stamped steel pulley I could find (much lighter than the aluminum version) and a two blade fan created from half of a 4 bladed OEM fan. A #MIN500 windage tray was fitted. Swain Technology thermal barrier coated our piston crowns and their anti-friction coating was put on the skirts. Swain also coated our tappets with anti-friction material and coated our entire exhaust system including some heat shields I fabricated with their “White Lightening” compound. Swain Company was very good to work with.

Holger's coated piston and tappet

Building a new cylinder head from casting # 12G940 is where the magic of this engine started. Obtaining an RPM range needed to win, in my opinion, was not possible with conventional Mini Cooper hot rod valve train parts so I looked for titanium replacements. I determined building a head around titanium parts which would have smaller high velocity ports, improved thermal dynamics and lubrication, and taller springs more suited to endurance stability could be a winning strategy.

SuperTech provided Honda 5.5mm stem diameter RSX valves, guides, lash caps, and seals. Those valves would nicely fit into the BMC combustion chamber after re-profiling the chamber by following steel patterns I made which located off the valve guides. Shown here are the “Longman” style valves in a Visard designed chamber against a non-ported casting.

9 Making Vizard chamber patterns and set up

Lash caps for the Honda valves would reduce contact loads at the rocker arm below OEM part values. With a bit of work Honda B/H series guides were made to fit the BMC head. SuperTech’s BMW M3 racing valve springs were selected with complementary retainers and locks. RSX valves are a bit more than an inch longer than OEM Mini Cooper valves so I fabricated three systems of aluminum heat sinks which would fit into that “extra” space. One plate would fit against the head, be restrained by rocker arm studs, allow cooling oil to pass under and around it, while also forming a base platform for our engines rocker arm stands. It has a simple drilled oil passageway for rocker arm shaft lubrication. The second system is formed of 8 aluminum collars press fit around the valve guides and tightly compressed against the head while bonding with thermally conductive epoxy. These strengthen the guides and conduct heat out of the guide into the head while holding spring seat cups. They also set installed height for the BMW springs. The photo below shows those parts trial fit so pushrod clearance might be laid out then machined in the plate first mentioned.

117 trial fit rocker shim with valve cover extention

Necessary valve spring pressure was calculated in Performance Trends software then set at 60lbs on the seat and 170lbs – 180lbs over the nose. The third system is a forged aluminum rocker arm cover spacer which raises the cover up allowing room for 1.5 to 1 ratio steel rockers to move. The valve cover spacer is notched to fit closely to the springs so radiated heat is conducted out of the engine to air or into engine oil. When batches of rocker arms were examined, OEM and aftermarket, I found them erratic about placement of oil spray holes. Some had spray holes and some didn’t, but none sprayed at anything useful. There was very little room for rocker arm stands in this engine. Note that the stands have been profiled round on the pushrod side instead of being squared off. Solid shims replaced springs on the shaft itself to positively locate the rocker arm tip over the valve stem lash cap. It took cherry picking 3 sets of rocker arms to get a set more or less the same. In the end, alignment was almost acceptable but not what I’d call “good”. This photo shows typical misalignment that must be corrected.

trial fit rocker arm shaft side view

119 trial fit of shim and shaft and extention top view

I fabricated an oil spray bar system pointed at the valve stem tip lash caps which will subsequently flood the entire rocker box area. It is installed above the rocker arm shaft assembly. Oil is metered to the spray bar by a #56 Ford carburetor jet held captive below the rocker arm stand-to-shaft spray bar fitting. Spray bar holes are #72 drill size. Unmetered oil from the rocker arm squirt holes is allowed to spray wherever it ends up. I believe in operation the springs run about half submerged in oil acting as coolant. After the Canadian / American Challenge National race the valve train was inspected. No wear or change in rockers, springs, lash caps, clearances or pressures was measurable.

Head porting was minimal but yielded flow numbers nearly as good or better than our “Longman” head while using slightly smaller (37mm IN and 30mm EX) titanium valves. Special valve seat material isn’t needed because the seats don’t get very hot compared to typical non-coated castings. However I installed beryllium copper seats anyway. The photo accurately shows there is zero extra room for the seat installation.

1 Beryllium copper valve seat set loose in chamber

Holger engine Gyptal application 003

The head’s combustion chambers and ports were thermal barrier coated by Calico Coatings, who are also very nice people to deal with. After all porting and modification machine work was completed and just moments before this head was packed to be shipped to Calico, several small casting pits were discovered in the roof of an intake port which were impossible to reach easily. While the head passed a vacuum test I became nervous the pits would open up to water in racing service.

Holger machine work head flaw enlarged

I milled a large hole in the top of the head, inspected the back inside of the castings internal surface for corrosion damage or a thin spot, and then installed two Lock-n-Stitch repair pins which removed the pit and surrounding metal (which appeared to be in fine condition) for security. Then I plugged the top of the head similarly to how I fixed the block deck. This led to re-pressure testing at 30lbs both engine block and head castings when torqued together for cooling system sealing integrity.

mini cooper pressure test 003

Calico Coatings made extra efforts to stay on my assembly time schedule by returning a finished coating job to us by our previously agreed date, despite my delay in shipping to them. They were generally “heads up” in all regards, also more than fair by charging us only what was originally quoted.

Calico also coated our intake manifold. By not allowing excessive exhaust heat to enter the head casting, elimination of a water bypass system is possible. Minimization of combustion heat to the oil via the piston was also accomplished with coatings. Subsequent testing indicated an external oil cooler isn’t really needed now.

* Do you dyno your engine builds? Do you know the HP, torque and compression ratio of the engine?
* Anything extra to add?

Some engines I will run on an inertial dyno at a track if it’s easy and we have time for fun. Otherwise I let track speed data tell me how strong an engine is. In this case other thermodynamic testing was more important to investigate than chasing a dyno HP result so we ran this engine a lot doing that. I found in a half dozen operation cycles at 75 lbs initial oil pressure our water temperature rises from ambient at idle to 215 degrees F at 6000 RPM after 22 minutes run time, stabilizing at 210 degrees F at 7000 RPM after the 23rd minute for as long as the engine was run thereafter. Twenty to thirty minute testing cycles simulated typical race duration. Oil pressure dropped to 55 lbs by the end of testing. Pyrometer temperature (sender about 10 inches down the center header tube from the exhaust header flange) peaked at 1600 degrees F. Tests were run with the engine installed in its chassis.

31a Holger engine heat shield & headers 004

Because time for “on track” testing had run out we made a few hot laps around the neighborhood where my machine shop is located. That revealed a flat spot in acceleration between 4500 - 5000 RPM. I felt carburetor reversion was occurring so I made velocity stack extenders to increase the mass of air moving forward into the carburetor vs. the mass of air trying to come back out from camshaft timing spit back. The parts shown in the photograph were epoxy cast into a two monolithic blocks for ease in assembly to the SU carburetor pair. This added volume of air eliminated the acceleration flat spot.

Mini cooper velocity stack extention parts

Early in testing the camshaft and tappets failed completely. Seven of the eight lobes were essentially gone. Two tappets had rubbed through to contact their pushrod ends. Typical causes were investigated and ruled out. The engine, gear box, and final drive was stripped and examined closely. Super magnets placed ahead of the oil pickup saved bearings, gears, and piston skirts nicely. Note the nearly clean oil filter media found in the photo below when the engine was disassembled for failure analysis.

Holger mini cooper oil debris check

Nothing was damaged except the cam and tappets. Because any specific cause of failure was uncertain we elected to forgo further metallurgical diagnosis to take a more certain solution path of upgrading to ceramic tappets. Ceramic tappets are compatible with any cam blank, require very little lubrication compared to conventional tappets, don’t need a break in cycle or ZPD additive, and can be moved from lobe to lobe later on if needed. But ceramic tappets cannot be run loose or run into valve float. Ceramic tappets cannot be allowed to pound freely against the camshaft so spring forces must be carefully selected for the RPM range an engine will achieve. I asked Bill Smith of Cedarville Utah (no relation to Smith Brothers pushrod company) to make a set which would interface with an identical replacement camshaft but eliminate the BMC / Ford bucket style design allowing a set of shorter pushrods to be re-fabricated by Smith Brothers. Those parts eventually arrived – beautiful parts indeed. Ceramic tappets look like standard solid lifters but have hollow centers, are very light, just 3 grams heavier than the Ford 427cid bucket tappet, but eliminated tappet oil weight gain so their dynamic loading is much improved.

After the engine was reassembled oil pressure test cycling resumed attempting to learn the lowest possible pressure which the engine could survive on. I’d noted more pressure drop than I liked from “cold to hot” was occurring. After another half dozen run cycles it became apparent our “upgraded” race pump obtained from usual BMC sources was not performing well. When pressures dropped below 30lbs at 7000 RPM and 15lbs at idle in half hour test cycles the engine was again removed and stripped for examination. I found both oil pump mounting bolts were loose and one of the screws holding the pump body together had been blown apart. We surmised jerk from the cams aggressive profile was overloading the pump fastening system. Looking inside the pump for end play (or lack of end float issues) I found odd wear patterns like the impellor was bouncing around. At that point I researched BMC oil pump history finding older models had used more retaining bolts than our block was drilled for. So I drilled our block for the “extra holes”, cross drilled fasteners for safety wire, and began to modify several new “race pumps” from various vendors for better sealing and retention to the block. Additional mounting holes would be placed where the weld material was added to these castings shown in the photograph.

Holger oil pump 002

Along that path I found Brian Waters Racing who sells a true BMC “A+” race pump – it is better in every way – so I junked what I was modifying and ordered one from him.

holger Mini Cooper BWR oil pump 011

Brian’s disassembled pump parts are on the left side and a generic “race pump” from typical vendors is on the right in the following photo.

Holger Mini Cooper BWR oil pump 002

BWR (Brian Waters Racing) also sells actual ACL competition Mini Cooper crankshaft main bearings (The Swiftune crank uses Honda Accord CB1223-P rod bearings). So I ordered a couple of sets of those too. I installed main shells providing a 360 degree oil channel. These are not to be confused with regular production ACL bearings sold by most vendors as the high performance Mini Cooper bearing.

When the lower end of the engine was stripped for bearing replacement after the new oil pump was installed I was shocked to find existing bearings were in near perfect condition after being run at such low pressure for as long and often as I’d been doing. And the ceramic tappets and cam were also in “as new” condition. All good news considering the National Canadian / American Challange race was just a week away.

However a main cap next to the flywheel was broken. It fell out in my hands when the ARP main studs were loosened. It immediately failed a magniflux inspection, then became two half caps with a slight tug.

Rear main OEM cap mag test crack area

We surmised a huge clutch shudder coupled with a very heavy OEM flywheel, which had been in the car after it was worked on by the other shops, had weakened the cap before a Swiftune Feather light unit was installed (which fixed the shudder entirely). The Swiftune set up removes more than 4-1/2 pounds unsupported cantilevered weight off the crankshaft. The remaining main caps were magnetic particle inspected and found to be “iffy” but I reused them anyway. The front cap is weak because of holes drilled into it for timing cover fastener attachment.

Front main cap Mag test rear view

If I build another BMC Mini Cooper engine I’ll not fuss with the stock caps at all and install billet steel replacements. In this case another rear main cap from a different block was fitted and the engine re-installed for testing to resume.

I can mention in our testing process Redline 50w oil performed well. We also tried Brad Penn 50w racing oil and Valvoline VR1. Noteworthy for consideration is considerable quantities of Brad Penn oil remained stuck to internal engine parts for several weeks, long after Redline and Valvoline had run off. With a Brian Waters Racing oil pump and Redline 50w oil our engine pressure regulator is set for 50lbs pressure cold, then doesn’t change much from that value in competition at any RPM. I modified our oil filtration system to use twin Fram HP6’s (or the cheaper WIX equivalent for break in because you just cut them open anyway) plumbed in parallel vs. a tiny one cup OEM filter nearly everyone else uses. I measured zero pressure drop across them while adding more than 2 quarts capacity to the sump system.

Holger Mini Cooper fuel line pinch 003

Because I measured only 15 degrees temperature drop across our oil cooler with an absolute peak temperature of under 240 degrees F, I feel an oil cooler is not needed. The surface area of the filter cans has become the cooler. Removal of 10lbs of traditional cooler and plumbing off the left front of this Mini Cooper would be a great enhancement. Oil analysis by Blackstone Laboratories after the remainder of our test cycles and running our Nationals weekend of races found no lubrication deterioration vs. new oil. Blackstone then recommended 750 mile retesting intervals until a maximum oil life was eventually determined.

We were very rushed moving the Mini Cooper from my shop to the track on time for technical inspection on the week of the Canadian / American Challenge races. No issues were found in scrutineering so we ran qualifying laps directly; without any significant tune up efforts. In testing, our engine had been timed by ear, and simply checked to be less than 32 degrees advanced. The SU carbs had been adjusted more than a year previously by looking at the plugs a few times on the old engine set up and monitored with my Innovate A/F gauge back then at Thunderhill. We bolted them to our new combination “as is” ignoring elevation and air density changes between the two race tracks. Our valves were checked just for changes in clearance. Valve clearance with ceramic tappets is .010 IN and .012 EX which could likely be decreased a bit. I’d retained a sensor bung in the exhaust headers for an O2 sensor thinking I’d use my Innovate A/F ratio gauge on track at Sonoma, but we ran out of test dates after fixing these developmental mechanical issues. I’d also added a tap for measuring exhaust back pressure at the collector. It was zero with our headers and Flow Master muffler. From collector to muffler is 60 inches connected by a 2 inch diameter straight pipe. We always ran the engine on 114 octane leaded race gas despite its low compression ratio. The car owner wanted to do that.

Mini Coopers have a duct tube going from the front of the car to an OEM heater box. When the heater is removed some racers use that tube to duct air to the back of the engine where the carburetors are. Usually the tube is just laid in there. I pushed that design by insulating the duct, installing a velocity stack for it behind the grill, installing a very tall valve cover to dam air trapped between the engine, hood, and firewall, and sort of bundling stuff up so air had to go inside the engine to vacate that space. I positioned the duct outlet with a 90 degree plastic elbow so it blew directly into the velocity stack area. This tube was tested to flow 3x the air requirement of our engine at race speed. I was pleased to notice our “heater induction” and “non-air-box-air-box” were working fine when the car is on a track.

Holger Mini Cooper fule line pinch 002

The carbs were sweating chilled water while sitting above a tight fitting header heat shield when the car owner came in from doing his qualifying laps. And I could hold my hand on the SU fuel bowls without burning it. At previous events there had been boiling fuel in those areas. Swain Tech white lightening coating worked real well for us because it had been applied to our headers and my custom heat shield in addition to the entire exhaust pipe.

Holger heat shield progress 003

Holger heat shield progress 006

In the photo below notice how closely the heat shield fits the fire wall of the car. I feel it is important for power production to keep hot things hot where they need to be hot and cool things cooler everywhere else. And if you can dam a bit of air into doing other good things along that path – so much the better.

Mini Cooper heat shield trial fit in engine compartment

As raced I put a length of roll bar padding between the engine sump and front cross member sheet metal to block air coming in the grill from going down under the car. Typically this is done with a front spoiler which is illegal for stock class cars. So I lowered our car to 3 inches between the pavement and oil pan – about the height of a spoiler - then blocked the air path so it had to go up around the engine and pass the radiator to exit, or into my velocity stack “heater duct” inlet. There are no rules about gasketing the engine inside its bay similar to the way Porsche does. We also bent our mandated stock grill louvers to angle air up-and-in instead of being flat obstructions. I feel the induction system for our engine starts about 2 feet in front of the car so its grill and engine bay entry is part of its carburetion path.

Holger Somoma Race 001

As raced, our 1310cc engine had 10.2 to 1 static compression ratio and produced 97 HP in one quick dyno pull at the track on its bone stock SU H-4 carburetors. Just off the dyno I literally bumped the distributor a small nudge ahead with my fist. Gary Hubback had given the RH carb a quarter twist more jet a few weeks before after listening to the engine pull through its range and when shifted on a long straightaway. We sent the owner out to win his main event with that as a “tune up”. I’m sure there is more power to be found if we ever gave this BMC engine a proper tuning workover. On the other hand, we beat a lot of cars claiming 120+ HP in their modified classes, in addition to winning the stock class outright, so maybe it is ok as is.

Holger Sonoma Race 015

However I feel more power isn’t the key to making this Mini Cooper run faster. Front tire traction is the issue. Despite a very good driver, this engine often pulls hard enough to melt our front tires after about 5-7 full out laps. I’m thinking how engine heat blown out the LH fender well by the radiator fan needs to be directed up... thereby removing about 20 degrees of temperature rise off that tire while converting it to modest downforce...but aero modifications are illegal in our vintage stock class….but racing is all about thermodynamics and aero control…It was a frustration the rules would bump us out of stock class if I removed glass headlights to help vent our fenders, which I really wanted to do.

This article was to cover just the British Leyland engine build, but my perspective is; all related steps and events told here are also part of any vintage engine build up. To make serious advances over what an OEM 50 year old engine did requires testing and reworking modifications as an integral part of the job. A build for performance in the vintage arena cannot be just popping some pistons in and adding an aftermarket head with a catalog camshaft. A vintage rebuild makes more demands of its curator than that. And any engine is a part of a car that only works as well as the systems which support it. Building a race engine is part of development of a car, and an evolutionary stepping process. This car had an engine when it came into my shop and I’ll build my client a better version of this one if he ever wants me to do so. And I’d improve its support systems again even further when I install it. One of the nicest moments at the Canadian / American Challenge races came in a few comments made by vendors and a couple of other car owners, that our car was “the most legal Mini Cooper in stock class”. I’m not sure how true that is, but it was received as a very complementary observation.

I’ve also held in my hands camshaft blanks for revised firing order “A+” engines that have custom crankshafts to swap firing orders around. I know that small groups of racers in Australia, Europe, and Canada are also running handmade titanium valve trains of various sorts – some in aluminum cross flow heads. I’d guess my version of this classic British Leyland engine is about 7-8 years behind secret current (2017) state of the art. But it sure was fun for my car’s owner, buddies, and I to do what we did. I hope you enjoy our story.

Epilogue: Since the National’s in 2017 this Mini Cooper was stored waiting for the 2018 season. I prepared it for an event in Sonoma set for early June 2018 but various health and other circumstances indicated the car should be put up for sale after we ran that race. However, it sold very quickly so was never run. A buyer in Los Angeles who has no current plans to run it is the new owner. He’s more of a collector-racer than a racer-collector who’s deeply committed to several new classes of electric car racing and production.

That is the majority of what this article will cover. Lastly, please share any photos of the engine, its parts, and any other shop images you feel like including.

Done sir, I enjoyed writing these paragraphs. I didn’t put much effort into formatting the pages or reducing the size of photo files. I figure after editing your staff would be much better at that than I. This long story tells about half the work and machine operations needed to build a strong running Mini Cooper engine. If you wanted more data because some gaps or jumps in narrative pop out to you, send a few more questions and I’ll figure an addition out. Most of these photos were electronic chatter between the car owner and myself as we progressed day by day so many were taken with a cell phone instead of a proper camera. I hope they are useful to you. But if there is something else you want to see let me know. I’ll look through my client archive file to see what may turn up.

Thanks, and I look forward to hearing from you.

Best,
Greg

Agreed, Best regards, Ladd Fowler

Final epilogue - This engine and article gained me a nominaton for "Engine Builder of the Year" from Engine Builder Magasine. The nomination didn't end up with a win over 11 other builders but it was still very nice to be considered for the honor.