[Sun Tuned]

As it pertains to this thread, I’m going to share what I’ve found in the last 4 Pontiacs engines I’ve built in this last year.

The first 2 were both 455’s. What I would consider higher end of the spectrum builds. Kre or edelbrock 325 cnc type head builds. Block end of the deal were both stock cranks with nothing more than eagle H Beam rods and lightweight normal 2 relief pistons. Basically the same block we all are putting together.

Both these guys were in a bit of a hurry, so I got them to order already blueprinted oil pumps from Butler. Now as I understand this these are Schuman pumps? In other words they come to butler already supposed to be fixed and ready to go. 235.00 each I think they were. And they were clean and looked the part anyhow.

Put both in and they went together about 4 weeks apart. Both were 60 lb pumps. Crank clearances on these two builds were .002 on the rods and .0025 on the mains, endplay was .006 on both. Thrust not touched , I got a thing about that. Rod dude clearance in both was if memory serves me correctly right at .018 to .020 .Lifter bores look real good …all that.

With 30W break in oil both had great oil pressure cold right at 65-70 lbs. however when at normal hot idle we looking at 10-15. The one was just a bit higher. By about 5 lbs.

This bothered the hell out of me because I’ve never built an engine with hot idle that low. Until these two I’ve never built an engine I had not prepped the oil pump myself either.

Fast forward about 2500 miles and the one guy decides we pull this engine and sort what’s going on and I agreed. Here’s what we found…

The pump that’s supposed to be “blueprinted “ has gear to pump body clearance of .004. But the biggest issue I found was the bypass ball would not completely seal on its seat. I sprayed a column of carb cleaner on top and watched it literally run right out the bottom of the seat nearly as fast as I sprayed it in.

After working on that for about 15 mins I got it to hold the liquid above the ball under the balls own weight. Put it back together with .0015 clearance. Put it back in car and now hot idle is rock steady at 35, that’s where I’m used to seeing em at.

We’ve since fixed the other one with same results.

So the last 2 I’ve done I just bought standard Melling pumps like I’ve always done and just did it myself.
Have not had first ussue that way. But I will tell you the last two pumps leaked at the check ball seat as well. It looks ok enough. But if you put carb cleaners on top of the ball I’d highly suggest monkeying either that till it’s dry underneath before putting it in service.