I don't know what happened to my original post, but it's gone. Anyway, I posted about a low oil pressure problem on my new 427 big block that got worse when the engine warmed up. The general concensus was that I probably had some bad bearing clearance, or clogged oil filter, and a few other suggestions.
Well, none of the above. I found the problem. I pulled the pan and started looking around. What I found, I couldn't believe I didn't catch on the engine stand!
The oil pump wasn't seated fully on the mating surface of the rear main cap. It was held almost an eighth of an inch off on the back side (closest to the flywheel) because the body of the pump was interfering with the one of the nuts on the ARP studs holding the mains.
I also replaced the pump because it was sticking. Rather than risk putting a marginal pump back in, a new high volume Melling is cheap insurance.
But what I did was to take off that nut and grind it down to about the thickness of a bolt head, and then the pump cleared fine.
It is now fully seated on the mating flange.
This is something to watch out for if you guys build a big block Chevy with an upgrade to ARP studs rather than bolts on the mains.
CHECK THE OIL PUMP FOR CLEARANCE!!!
:eek:
The bearings looked fine. In fact, the engine looks great. The oil is perfectly clean with no metal fragments at all.
I fired it up and let it get warm. 42 psi at idle cold, and a full 30 psi with the engine warmed up. Rev it and the gauge goes way north.
So it's fixed. What a huge load off my mind.
Same thing with a small block with arp studs. Even tho one stud is shorter than the other, it is still too tall that it interferes with the oil pump. Can't beleive ARP hasn't corrected this.
Momo:
I ran into the same problem with my 454. One of the ARP main stud nuts was keeping my Melling high volume oil pump from mating up flush. It took me a couple of trips over to the dremel before I correctly ground enough metal off of the oil pump.
Corvette Store
Remember my oil pressure problem?
