The ultimate grey motor article.

This is an article that I always enjoy reading, many thanks to Ray Bell for writing the article 

The Grey Holden Motor - racing giant of the fifties and sixties

It was built from 1948 to 1962, with over a million of these engines built in that time. They were used in rallies, road racing, speedway, drag racing, boat racing - all forms of motorised sport. Special heads were built for them, special races were run for the cars that carried them. They were an icon unsurpassed in their time.

During 1963 and 1964, the number of special races held for Holdens fitted with 'grey' motors only reached an all-time high. Their popularity waned after that as the 179 took over their mantle, though not in the same numbers for several years. But at the speedways the Midgets fitted with them wailed on, their unique scream echoing from the boards surrounding the dirt ovals.

Yet back in 1950, Bob Chamberlain had told John Cummins, "It's a terrible engine, you'll never get any decent horsepower out of it!"

By the end of the reign of Appendix J in 1964, at which point the grey motor reached its zenith with original heads, 156bhp was cited as the top horsepower seen. In Repco Holden form they were to give 190bhp, and Merv Waggott's twin-cam engine gave 220bhp.

Between those years, the humble 2160cc Holden engine had powered no fewer than 25 entries in the Australian Grand Prix, with some of the most interesting engines among them. Jack Myers' car with the twin-cam Waggott; several with Repco Hi-Power heads and the unique Dud Dansie car using the Dunstan rotary valve engine. Only two AGPs from 1952 to 1962 didn't have grey motors in the entry list.

Essentially, the Holden engine was a miniaturised Chevrolet inline six. But it had a few refinements compared to that engine, especially in the lubrication system. Where the Chev had splash feed to the big-end bearings, the Holden had a fully pressurised system feeding all points.

It had nothing special to attract the hot-up set, however. Simple bathtub combustion chambers, siamesed inlet and exhaust ports, just four main bearings for the cast iron crankshaft, it was a very basic production engine. What it did have going for it, though, was availability in spades. Within just a few years of production commencing, Holdens were everywhere!

One of the first to start race-preparing the engine was Peter Lowe, who fitted one to his Bugatti type 35. John Cummins recalls that he had an oil cooler, adapted an MG TC gearbox and fitted three SU carburettors. At the same time Jack Myers started work on his for touring car racing, which saw him frequently confront the regular star of this class at Mt Druitt - Don Gibson with his '38 Dodge.

Cummins then bought his own engineless Bugatti with the intention of fitting a Holden. Len Sidney built his engine in Moorabbin and paid special attention to the cooling system. First he hand-scraped the block so that the tops of the cylinder walls stood a little proud of the rest, then he made a gasket of copper sheet that blanked off the water jacket holes between the block and the head on the manifold side.

The purpose here was to force the water, which entered the block on the manifold side under pressure from the pump, to travel across the block between the cylinders. Then it rose to the head and travelled across the top of the combustion chambers and around the ports before exiting via six pipes tapped into the head adjacent to each cylinder.

"We used a Citroen water pump from a Big 6," remembers Cummins, "and it was a matter of trial and error to get it to run at the right speed. It took us two years of slowing it more and more before we got it to cool properly."

In Addition to this, Sidney put braces on the main bearing caps to help contain the power. "General Motors wasn't interested in racing, of course," Cummins told us, "but it always seemed that they were watching what we did and changes in production followed our development." Later engines had main bearing caps that were easier to brace.

Another modification was to tap into the oil supply to the cam bearings and direct a copper 'squirter' at the distributor drive gear - an area where lubrication was scant. "When Holden brought out their next engine revisions they had a nice little change in the casting that did the same thing!" Another difference in this engine was the marrying of the front single exhaust port with the rear siamesed port, and vice versa, to form the extractors.

This engine is the earliest we have figures on, as it was put on the dyno by Albert Ludgate in Adelaide. "It gave about 65 or 70 horsepower at 3,500rpm," John recalls, "and it wasn't worth two bob at 4,500! We fiddled with needles in the triple 1¼" SU carbies and got 116 horsepower at 4,500." This was almost double the original Holden power output.

During this early time, Repco saw prospects for the engine and started developing their own cylinder head. They bought a Raymond Mays head made for Ford's Zephyr engine and studied it, then Phil Irving and his team designed and built the Hi-Power head. Immediately it went into hands just waiting for an economical race engine.

Paul England built his Ausca around one and many went into Midgets and boats. Touring car racing was stepped up by several hitting the track in 'humpies' fitted with Repco Heads and MG TC gearboxes and a revolution took place. Repco kept on developing these and had an FE Holden fitted with one for experimentation. On the odd weekend it would be despatched to various circuits for Stan Jones to drive.

Repco management weren't aux fait with the weekend activities, however, and put a stop to it when they found out. Charlie Dean, in charge of the project, gave all the racing parts - including the engine - to Bob Holden and told him to buy a car to put it in. Thereafter Bob got a lot of help from the backroom boys at Repco as they used his engine to learn more.

"But they warned me to only do one meeting on a crankshaft," Bob recalls. "Friday we'd pull the crankshaft out and replace it ready for Saturday, which really wasn't as hard as it sounds. We'd use the same bearings and the boys would have bets amongst themselves about what oil pressure we'd get with the different crank as the journals were never exactly the same diameter."

The first Repco-Holdens put out about 140hp, Paul England's may have been a little better. The 4-bearing bottom end was starting to take a beating. Some time late in the fifties one that took an extraordinary beating was the engine in Holt Binnie's sports car - it blew up.

Renting the workshop at Binnie's garage in Mosman was a young and enthusiastic Ray Eldershaw. Binnie told him to rebuild the motor, but Ray decided that he'd only rebuild it if he could do it his own way. Ray wanted to give Binnie more power and show his own engine building skills, but Binnie just wanted a replacement for what he had.

The stalemate ended two weeks before Bathurst, when Binnie walked into Eldershaw's workshop and said, "Okay, have it your way! Build the thing!"

With precious little time available, Ray bored the block to 3.1875" and fitted Weslite pistons, a new cam and three 1¼" SU carburettors. "It already had a good head," Ray recalls, but he gave it better lubricant flow and drilled and tapped the block to fit an oil filter.

Standing inside Hell Corner at Bathurst, Ray watched as Holt practised. "He's not going to get around another lap with clutch slip like that!" he said to himself. But it did come around, again and again, and when practice was over Ray asked about it.

"That wasn't clutch slip," said a beaming Holt Binnie, "that was wheelspin!" It was then that Merv Waggott arranged for the engine to be put onto his dyno, where it showed 126bhp - over ten horsepower more than any previous grey motor had shown on that dyno. Not so impressed was a Mr Bartlett from GM-H, who reckoned they should never get that sort of power.

By this time the fire-breathing Repco-headed touring cars had been reeled in and Appendix J put regulations down that led to more structured development, and that development rushed on as the more adventurous Holden racers strived to chase the few Jaguars that were in front of them.
In the meantime the Waggott twin-cam head had been in production for some time. Jack Myers had the best-known of these in his replica of a front engined Cooper and raced and hillclimbed it all over the country. Many more of them went into boats, but one would eventually find its way into a pretty little Queensland-built Centaur GT car that was driven by John French.

The Waggott twin-cam played only a very small part in the story of the grey motor, but it was the ultimate development form. With a magneto out the front of the crank, a dry-sump system, neat castings that took the chain drive to the camshafts and the neat cam covers each side of the spark plug valley. It also had a finned alloy sideplate cover.

Almost an aside in this company was the Dunstan rotary valve head from South Australia. It was shortlived and participation in racing was limited to a brief period in Dud Dansie's BBM. Its AGP entry was in 1961, three years after Myers last ran the Waggott in the race and just a year before three Repco-headed engines would signal the end of AGP participation for the grey motor.

From that point on there were basically just two lines of progress. Speedway had a mixture of original heads and Repco Hi-Power heads, road racing had hordes of touring cars with original heads and a few oddball cars with Repco heads.

In speedway there was a leaning towards fuel injection, something not obvious at all in road racing. Mostly the local McGee injection, it was fitted to both original heads and Repco heads. Of course the fuel restrictions in road racing didn't apply at the dirt tracks and so it was a different ball game altogether.

One of those who did a lot at the speedway was Gordon Benny, originally from Adelaide. Like others he remembers milling a flat on the main bearing caps and using head bolts to put a 1" square brace over them. "We used to make up spacers that would sit between the stiffener and the cap to fill the gap, but we'd leave about 3 thou clearance," he told us. This would put a preload on the cap to hold it in place.

Other 'tricks' he used were to select cranks that had come out of engines that had done about 60,000 miles without any rebulding, polish the journals, but leave the balancing alone. "We'd pick a block and a crank, then assemble it with just the bare crank, no seals, and then spin them by hand. Some were a little tight so we didn't use them." Like Len Sidney, he drilled a very small hole in the oil gallery to feed the magneto drive.

They bored their engines to the familiar 3.1875 and used cast Wise pistons with lumps on the crown that pushed the compression up. They had lots of gasket problems, usually resorting to painting them with Silvafros and fit them wet. "Solid copper was too expensive!"

Valves were "as big as we could get in there," while Triumph Tiger 100 valve springs were used. "Holden spring caps were no good, we used ones off Austin A40 valves as well as their colletts." He built his own cam grinder and copied the MG TC camp profile but added an extra 1/16" lift.

Bronze and alloy timing gears were used. Gordon had an interesting way of adjusting the cam timing with these. "We had spacers and we'd move the gear backwards or forwards on the cam to advance or retard the timing," he told us. "Advancing the cam 3° to 4° would make the car come off turns better."

Ultimately the Repco Hi-Power heads delivered 180 to 190bhp, while competition was intense to see what could be had out of the original heads in the touring cars.

One of those working to this end was Bo Seton. Like many he was racing a car used on the road, but with the vigour of youth the engine was in and out many times as changes were made. "We had a 35/70 cam and Kenny Waggott made followers with a small radius for them," he says. "We ported the heads and put in valves about a sixteenth bigger than standard."

One day Bo went to Warneford's at Woolloomolloo to get a new set of 1¾" SUs, but on leaving there he crashed into a taxi. "We had it towed out to Ingleburn and a couple of days later we were racing at Warwick Farm."

Like Benny, Bo found that the pistons he used, in this case CME castings, "were like Anthony Horderns, they kept on growing!" Bore clearances had to be large. He made his own manifolds and exhausts and fitted a harmonic balancer off a Jaguar XK engine and had steel timing gears.
"We used ex-taxi cranks," he says, "they lasted longer. Midge Bosworth bought a new crank for a Catalina meeting and broke it in practice." In time most learned that 6,200rpm was a critical speed for the crankshaft.

Seton's car was just one of the quick ones in Sydney. There were quick ones all over the country, of course. Norm Beechey in Melbourne, followed by Dave Price, Norm Gown and others, all had their tricks. In Adelaide Peter Finch was among those racing them, but claimed that you were lucky if they held together.

A whole industry built up around these engines and the desire to make them fly. Jimmy Wilkinson's Scientific Gas Flow business did the head for Brian Muir's engine. This was a follow-on from a Merv Waggott build for Ian Geoghegan, the original blowing itself apart in 1960. Waggott, impressed by Ray Eldershaw's abilities, told Muir to go to the Mosman mechanic for his replacement.

Fitted with two downdraught twin choke Webers on a plenum-type manifold, it had cast Wise pistons, was bored to the limit at 3¼" plus 0.030". This would have required either a very early block (rumoured to have been cast in Canada but this has been proven to be incorrect) or an FB or later casting to get sufficient cylinder wall thickness.

The engine had a Dodge harmonic balancer on the front of the crank as fitted by Waggott. When Muir came to him, Eldershaw guaranteed him 140hp and 120mph down Conrod Straight or he didn't have to pay. The dyno showed 142 and the fastest speed in the flying eight was 122mph.

Fastest of all as the era drew to a close was the Bob Grey-prepared Boomerang Service Station car. This was owned by Joel Wakeley and raced by Spencer Martin and Bo Seton, reputedly giving 156bhp on the dyno.

When we think today what basic road engines approach these figures it seems ludicrous. But when the Holden came out originally it sported only 61bhp (up to 72bhp by 1956), and such gains have to be seen in the light of the times.

The old grey engine was never designed to be anything other than a useful and economical workhorse. Bob Chamberlain might not have been proved right in the finish, but it took the combined efforts of hundreds - if not thousands - over ten years to make the progress that was necessary to get the development up to those levels.

The people doing this got to know all the tricks. Peter Waggott remembers cleaning the flashing off rods and shot peening them. John Cummins reckons it was necessary to use the later rods that didn't have the oilway drilling the length of the rod.

All of these things became lore in the time of the grey motor. Today people are starting to forget the old grey motor that helped build the industry and the sport we enjoy.

Ray Bell

With credit to Motor Racing Australia and Chevron Publications.
Edited by Ray Bell, 13 December 2014 - 22:06.

Greg Smith Originally the Opel Super 6 of 1938 and a pure German designed engine with all the drawings and patterns spirited away for GM Germany to Canada as the storm clouds of war were building, Witness the Metric cam gears, oil pump gears, and bore spacings (they are 75 mm) not 3 ' and the metric distributor gears and Bosch units!! People who think these engines are either Canadian or Australian are dilusianal!!