Above: The Repco Highpower cylidenr head, with
three Webers and Repco extractors as installed
in Barry Ferrari's Holden.
FOR FIVE YEARS now, Barry Ferrari has campaigned one of Victoria's best-known modified production cars, an FJ with an unusual top-chop and sponsored by Wynns.
During this period Ferrari's team has been twice National champion, three times Victorian champion and, until the recent '70 Big Go, held the record for E/MP class. With this sort of success, a great deal of development on the car is called for.
Recently Ferrari obtained the magic 200 b.h.p. from his Holden engine, a 132 cubic inch donk more than 10 years old. This is how it was done. After three years of success with the basic 132 c.i. engine and the cast iron cylinder head (worked over many times), the Wynns team began to look further afield for a power plant. Many engines came under consideration, including the later Model 186 Holden engine and the rather heavy but extremely powerful Chevro let six engine of around 231 c.i. Finally a crossflow Repco head was purchased and the decision to con-tinue with the old sideplater was made.
Preparations for the new head began immediately and many hours were devoted to planning and design. A complete crack test and visual inspection had to he critically carried out and after Dyno Dave Bennett gave the nod of approval that the head was OK, work began in earnest. Wynns boss man in Melbourne, Mr. Nes, Dumbrell, called in Norm Gown and John Stevens, both well known Vic-torian racing drivers and proprietors of Engine Developments. to figure the new set-up.
Many difficulties were encountered due to the fact that no one had ever seriously considered a crossflow head for drag racing. The head had been obtained from an enthusiastic Tasmanian and came complete with two twin choke. downdraft Weber 45 mm. carbs. so for the initial running the existing set up was retained. The engine was developing 130 plus h.p. with the iron head. so in order to pin some idea of what increase could be expected the crossflow head was bolted up and the engine sent to the dyno with Norm Gown to supervise proceedings.
 |
| The FJ itself at Calder |
With virtually no tuning the engine cranked 145 b.h.p. on pump as "first pull of the string". The indications were good, for the increase had been achieved without special cams or any head work. An unofficial record was subsequently established at Calder in May. 1970 with a blistering 14.89. The record was officially posted at 15.22 later in the day by Ferrari.
The New Motor
Encouraged by this success, work hastened en the "new' engine. Racing experts such as John Patterson Men-co Research) and Pat Ratliffe (Eddie Thcfmas), together with Norm Gown and John Stevens contributed to the end result. A "one off" camshaft ground by Pal Ratliffe was used. Pals long cam grinding experience coupled with Norm Gowns' testing in this department produced a cam-shaft designed for the job. Weslite 14:1 racing pistons were selected as they were manufactured especially for the Repco head. Com-pression ratio was reduced to what was regarded as a more realistic 12:1 figure. Eddie Thomas balanced the entire assembly including clutch, crankshaft, rods, pistons, even push-rods and cam followers. The head was then cc'd by Norm and ten days later the short motor was assembled to the desired tolerances and clearances. The stock oil pump was re-tained after checking, and found to be pump ng 35 lbs. per square inch pressure. which was considered adequate.
After balancing. the crankshaft was "Tultrided" to ensure long life and withstand the stress of racing. A moderately lightened flywheel was used as dependability was sought as well as horsepower. The peculiar design of the Repco head allowed six ram tube inlet manifold to be used carrying three twin choke sidedraught. 40 mm. Solex carbs. Correct jetting was achieved on the dyno as again there were no guides to work to. The original exhaust manifolds (headers) were used as they were designed by Phil Irving. They offered good Indy/ chassis clearance. Tailpipes 40" long and 21" diameter exit the gas from the headers.
Final step then was to fabricate a special distributor to complement the power curve, another undertaking by Eddie Thomas, and the fabrication of a distributor cap to fit under the inlet manifold. Would you believe its impossible to remove the distributor cap without first removing the inlet manifold! The engine was then finally assembled and Norm Gown drove to the dyno with fingers crossed.
After four hours running-in. the testing began. The final result was a whopping 200 b.h.p. with 185 foot lbs. of torque. While the engine work was carried cut. Ray Colley. proprietor of Col-ley's Body Works in Box Hill, re-painted the car in its original red, black and gold colour scheme in preparation for the next drag race meeting at Calder.
It would be nice to say that first time out after the mods, the car beat all records, but no such luck. There was lots of extra power but the poor tyres just couldn't take it. Another ratio diff was fitted during the day. along with new rubber. but it was the same result. More fiddling with eiff ratios. etc.. and a large pair of M and H super-sticky compound slicks now on order may cure this problem. Problems 'rise in all jobs like this. and the Repco heading of Ferrari's Holden was no exception. Headaches including removing a section of the fire wall to fit the rear carbie in, and fabrication of a new firewall, re-shaping inner guards to clear other carbies, moving of accelerator pedal and making up new throttle linkages.
A more detailed look at the Repco head shows up some interesting facts. Secret of the product is, of course, the hemispherical combustion chamber and the crossflow porting. An interesting modification took place on the inlet side of the head. In its original farm, the Rena) head has two long chambers which feed the fuel mixture into the cylinders — one chamber for each three cylinders. By carefully dividing each of the two chambers up into three equal sections. a six inlet port system results — a very practical and important development. To make the most of this improvement. Ian Heather. the mechanic responsible for much of the work, carefully matched each combustion chamber for volumes.
The first dyno tuning was carried out using standard pump gas, an "ordinary" set of racing plugs and the one-off camshaft. Experiments over the next few months with methanol fuel, different types of plug., and perhaps a "super" cam may sec even higher power output.
Article from Hot Holdens and Customs #2
Sounds rather fun and engrossing, Barry.
ReplyDelete