By its very nature, any racing engine, vintage or otherwise is always at risk of damage during use. Since truly original parts are a constantly diminishing resource, the long view of our sport requires that we minimize the peril to which we subject our equipment. In 30 years of race engine building I have seen many avoidable failures attributable to faulty installation, misuse and even mis-assembly. Many of those have been repeated over the years, so I would like to share a few of "the things that will bite you."
First, front mounted oil tanks in rear engined cars or rear mounted oil tanks in front engined cars. In the early '60s when dry sump systems became popular on British Formula cars chassis designers found it convenient to place oil reservoir tanks adjacent to front mounted water radiators. This required supply and return lines to run at least S or 6 feet. Often these lines were of insufficient inside diameter causing marginal flow of oil to the pump pickup, especially with cold oil. If you have one of those systems, try loading the tank with fresh 40 weight on a cool day and see how little dribbles out at the motor end. Even multi-weight oils and synthetics, though better in this regard,are designed to flow to a pump immersed in oil through a pickup no longer than about six inches. Naturally, unless large diameter supply lines are used, cold running starvation can result. Clear evidence of this occurs when you blip the throttle on a cold engine and the oil pressure momentarily dives. Return lines are nowhere near as critical, having positive scavenge pressure to drive them. Unobstructed, large diameter feed lines cure this problem although shorter runs are an even better solution.
Compounding the remote reservoir problem is the practice of running oil and coolant through frame tubes also used as structure. As elegant as this multiple usage seems, it's almost impossible to assure clean insides of a frame tube even when new, not to mention 30 years later.
Another problem which many of us cause for ourselves is mounting remote oil filters such that oil can drain back through the pump between runnings. This practice has caused the early demise of many Ferrari 308's where an anti-drainback filter is supplied from the manufacturer only to be replaced by a well intentioned weekend oil changer who uses a filter not so fitted. Don't point filter housings skyward or even horizontally if possible, it increases that critical period during startup where oil must fill the filter and lines before the motor sees any at all.
Another hazard lurking in some vintage oil systems concerns air leaks on the suction or supply side. These are particularly insidious because they won't necessarily leak oil to the outside, but can leak air into the oil supply. This aeration of oil results most often in fail- ure of main bearings beginning with the first main to be supplied. Rod bearings only seem to be damaged after the main bearing clearance wears to a point where oil previously destined for the rods leaks out the worn main bearing hole. Loose fittings, porous hose and more recently swivel fittings with worn sealing rings are often the culprits here.
Cooling systems can also bite you. It may sound trivial but the cooling system needs to be full of coolant to work properly. It can't get full if air is trapped in the radiator, lines or engine. In formula cars and sports racers coolant lines are often run at floor level to lower cg, but this creates an opportunity for trapped air at the radiator. Bleed lines run up high are the answer. Keep them free of silicone sealant by air blowing them any time an engine is changed. I can't count the number of times a disappointed driver has recounted his first few laps on a fresh engine where "the temperature was real high for a little while, but then got really cool. Then it stopped." What he saw, of course, was the engine overheating from lack of water circulation and then the misleading cold reading which gauges show when the water is gone.
In recent years many competitors have started using exhaust thermocouples to aid in jetting for optimum performance. Ideal temperatures are between 1250 and 1400 Fahrenheit, with lean jetting causing excess temperature and rich fuel going cold. Only problem is that mixture isn't the only factor in exhaust gas temperature (E.G.T.). Excess ignition timing causes cold E.G.T. (more burn occurs in the cylinder) while reduced timing shows elevated readings. So it is possible for an engine which has a bit too much timing to show low temperatures even if the jetting is ok, or even lean. The driver, noting less than ideal E.G.T. opts for still leaner fuel settings which combine with excess timing for a very unhealthy condition, usually scuffing a piston. All but small jet changes are best left to the dyno where their effect can be immediately verified in power output.
Every driver knows that over-revving can cause serious damage, but few realize that doing so for what seems like a very short timeto them, is actually a very long time to the engine. We have all missed a shift (or worse yet, engaged the wrong, lower gear) and hopefully backed off the accelerator immediately. Yet the onboard data I've examined over the last few years indicates that in most cases a minimum of one full second of over-rev has occurred. Doesn't sound like much, but at 8000 rpm that is 133 revolutions or more than 66 opportunities for the exhaust valve to become friendly with the piston. Even when extra valve to piston clearance has been cut by a conscientious engine builder, just a few rpm above valve float will cause contact and your race weekend gets cut short with damaged parts.
The cure here is to give the engine sufficient margin between operational redline and the point at which valve float occurs. I favor specs which provide about 1500 rpm of short term cushion, with a 9600 rpm shifted motor occasionally surviving an 11,000+ rpm mistake.
Almost limitless opportunities exist for damaging racing components yet I find that one of the major satisfactions of dealing with rare and valuable vintage racing parts comes from the additional thought and care required to keep our equipment both competitive and healthy to race another day. The irreplaceable nature of the original parts, unique to vintage racing, requires that we try harder than the rest of the racing community to preserve the cars we enjoy so much.
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