I have a Melling HV/HP oil pump. I have used a HP pump on one other engine, and I don't recall it having these problems. I fired it up today to do a little tuning, and when cold, it runs 75psi, warmed up about 60psi. This seems normal for a HP pump to me. But I have noticed a leak. Its on the driver side, dripping off the bottom if the inspection cover on the bellhousing. THe block is wet by the oil filter, but so the area around the dist., and oil pressure port. I guess I am looking for re-assurance that this is not a rear main seal issue. Does the rear main even see excess pressure? Anyway, tomorrow I am going to take off the cover, and pray the rear main is okay. I would even settle for it being the oil filter, but the pressure port, or the dist. would be a much more welcomed culprit. Any ideas?

 

I have narrowed this down to the oil pressure port. I have rules out the dist. and rear seal area of the intake. I have tried different fittings, even mounting the sending unit to a 45* elbow. It was on the firewall with a hose running to it. It still leaks. Its not getting worse, but it sure isn't any better. Anyone have any ideas? I have tried Teflon tape, as well as paste. Even letting the paste setup overnight. I am ready to stick some JB Weld on the threads and be done with it. Yes, I know I would regret that later on. Anyone know of an idea I haven't tried yet?

 

Okay, I need to back track. The pressure port was not it. I put a pipe plug in it, and it stayed dry as the dist. got wet. I took off the holding clamp, and it was wet under that. I am 99% positive the leak is from the distributor. Anyone know a solution for this? I had a new gasket on it, I added another one, and it still leaked. Any ideas?

 

might try lapping the distributor to the intake, make sure there isn't any burrs or other problems to keep it from sealing. there is no need for a Hv ot HP pump on a street engine, or even most weekend race engines. a M55 pump with a mr gasket #26 spring will serve all your oiling needs.

 

Yes I agree on the pump needs. The old one had metal ran through it. I used the new one b/c it came as a package deal with some other stuff I bought on eBay. It had the low pressure spring included, but I didn't use. Yes, I wish I had now. I thought about buying a new distributor, thinking maybe the oil control rings on the dist. may be worn. After keeping things simple, the oil pump is the culprit as the dist., intake, are the same. The oil pump is what is different from before.

 

There's no such thing on a stock HEI. Some of the aftermarket ones have O-rings cut into them, but GM does not. And in any case, they have nothing to do with external oil leaks.

Most likely, the reason it leaks, is because there's now about twice as much horsepower being transmitted by the distributor to the oil pump, which is simply a waste of power slowing the car down, and causing more stress on everything to do with the dist. That would include making it more inclined to move around and vibrate.

I second ede's oil pump recipe; that's the same setup I use.

 

No, there not o-rings. They are part of the dist. that controls how much oil goes from the oil passage right behind the dist. shaft, to the lifter oiling passages. Here is a pic. At any rate, you guys are right, a high pressure pump really isn't needed, and I should have used the low pressure relief spring.

 

Those don't "control" oil flow as such, they merely complete the passage, where the dist hole has to go right through the right bank lifters' oil feed gallery. There's actually about the same cross-section through there as the passage itself. But, to hold down the oil pressure loss from leakage there, some of the aftermarket dist builders do actually cut grooves for square O-rings in those places.

High pressure isn't a bad thing. In fact, the stock oil pumps in alot of these cars are "high pressure". Normal SBC pressure is 35-40 psi cruising, but these come from GM with a relief spring that gives about 50-55 cruising. The Mr G spring gives about the same as the stock high pressure spring, or the one in the Melling M-55A (the replacement for the stock high-pressure pump); it just costs less to do it that way.

Where you get into trouble is using a high-volume pump in a motor with stock oil clearances, whose oil flow is therefore no different from stock, and for which a high volume pump accomplishes absolutely nothing; but it requires the extra power to turn it anyway.

Use a standard volume pump with a high-pressure spring, not a high-volume pump with a low-pressure spring.

 

Ahh, I follow you now. I was backwards.