LYCOMING PERFORMANCE SINCE RESTORATION

Verbal Comments by Ralph Watson

(Compiled by the editor)

I am sincerely pleased and thankful that the car has been rescued from the grave, is now in the good hands of Ralph Smith and again is in use. Restoration from a very sorry condition has involved a great deal of time, effort and expense.

Although there does not appear to have been any times recorded in competition, which allow positive comparison with past results, it appears certain that the car no longer performs as well as it used to. This is rather a shame, but the reasons are valid and understandable. In recent times the Lycoming has been restricted to Classic Racing events of a much less serious nature. During the earlier period of competition, gear ratios, tyres and wheels were changed to suit individual venues, and during the period of Shell sponsorship the best possible fuel was used.

The original 290 engine, which was finally fitted with 320 type cylinders, has had to be replaced with a 320 engine, which does not incorporate several of the modifications made to the original, due to there being differences in several respects other than size. There were also several variations of the 290 engines, involving minor but important differences. The original engine was designated 0-290-3. If one could be found and purchased at a realistic price, to be rebuilt exactly as the original, this would be well worthwhile.

It appears that there is now a problem, diagnosed as oil build up in the crankcase, with consequent spark plug fouling. The replacement engine lacks the special scavenge pump which I constructed and fitted. It is possible that the scavenge system now in use is inadequate.

The original scavenge pump, which I made, was a dual pump, for good reason. (Editor: refer here.) This pump had two inlets providing for two pickup points, located as low as possible at each end the crankcase, to combat probable oil surge. Two pickups into a single inlet pump, could result in the intake of air putting the pump out of action, in the event of oil surge.

As a result of experience gained running the inverted engine, the holes forming passages from the rocker boxes to the crankcase were enlarged, as they now act as oil drains. In addition, oilways in the rockers were modified, to cater for the inverted engine arrangement.

Special pistons with narrow rings were originally used, whereas the replacement engine has standard aircraft components and this could be a contributing factor.

The fuel injection system is completely a one-off in terms of concept, design and construction. Provided that it correctly adjusted it is capable excellent results. When I sold the car, an instruction manual was provided but this appears to have been lost. It is therefore not surprising that there has been continuing confusion, regarding adjusting and maintaining the injection system. There have been problems setting the fuel pressure and as a result adjusting the fuel mixture, which in turn has caused overheating. (Editor: - In this connection, refer here and here.)

It must be accepted that now that the car is no longer competitive in open events, there is less incentive to spend unlimited time sorting out problems. What is more, the Lycoming is now fifty years old, has done a great deal of hard racing with resulting wear and tear, and replacement parts are difficult to come by.

There has been some controversy regarding the top speed of the Lycoming. In point of fact, a proper timed top speed run has never been undertaken. There were originally three crown wheel and pinion sets available, giving overall ratios of 2.1, 2.25 and 2.44. These were changed to suit a particular circuit, after having been chosen using a specially made graph. This was based on one I had seen published, incorporating tyre size, gear ratio, r.p.m. and m.p.h. as the variable factors.

As most flying quarter mile sprint events in the North Island were done with too short a run up to reach top speed, I would use the low ratio and do only standing quarter mile runs. On one occasion, at a Dargaville sprint, I unexpectedly found a mile run up, but having the low ratio fitted did only standing quarters until, with some persuasion, I took the car through at limited maximum safe revs and 127 m.p.h. I believe that it is bad for a motor to be held at maximum revs, with a light load and with the throttle partly closed.

The high 2.1 ratio and largest tyres were used for the 200-mile race at Ardmore and the following South Island tour. At 38 m.p.h. per 1,000 r.p.m. it was a great touring gear. On the long straights during the Ryall Bush race the car reached 3,600 r.p.m. and 136 m.p.h. This was during the first year of development. The compression was later raised from 6.5 to 8 and the valve size increased and as a result one would expect the car to be capable of, or possibly exceed 140 m.p.h.

Editor: -

It has been reported by an associate of the late Jim Boyd, that Jim told him that the Lycoming Special was officially timed, during a race meeting at the Pukekohe circuit, at 151 m.p.h. It is known that timing gear was set up on the back straight during several meetings when Jim raced the car. Ralph has calculated that the figure quoted is feasible, based on the tyres Jim was using and the gear ratios available, but so far no written record or further confirmation has come to light.

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