I was just pondering an idea. Buicks have higher tolerances in the engine than most other brands in the era (65-75) the engine will be built for longevity 100k+ miles. how would it work if you were to use a larger bearing clearance, closer to a chevy rebuild, but then a high volume oil pump? in theory the engine would need the higher volume since more oil is needed between surfaces. but would the passages to the bearings be too restricted since the oil needs to travel a further distance than lets say a chebby. Does this make sence or would one be better off building to the higher tolerances? Nate
This would not be the best idea for a long use street motor. Go with the correct clearances and standard oil pump with booster plates. Racers sometimes use looser clearances and the hi-volume pumps but they are looking for HP not lots of street miles. The key is to have a machinist that will make sure all the clearances are perfect, use good quality parts and break the motor in properly. For longevity build a low rpm torque motor and use highway gears.
HV Pump / Loose Clearance This was the way to go 25 years ago for street/strip cars. Even racers are using this approach less and less over time. One of the problems is the cam/distributor/oil pump drive. The big block buicks have the distributor and oil pump drive out in the middle of the timing cover. The oil pump shaft is pretty long and unsupported. The extra load of the high volume pump puts too much strain on the distributor gear and it starts walking around as the shaft flexes. The distributor gear can strip if a motor with a high volume pump is revved up cold - there's too much load on the gear. If you're lucky you might only twist off the roll pin that holds the gear in place - this is less likely to wipe out the gear on the cam, but the car won't run until the roll pin is replaced and the engine is re-timed. Racers usually run a bronze distributor gear that wears faster than steel, but won't tear up the cam gear. You can often find modified timing covers with a small diameter copper or brass line added to spray oil on the gear to keep it alive. All in all, it's better to build the engine with a straight crank and tolerances closer to stock. You can use the oil pump booster plate and an adjustable regulator and set your oil pressure up just fine.
The other important key is to make sure your timing cover and pump is perfect. I had mine blueprinted and get excellent oil pressure.
