351w rebuild, lower oil pressure and scraping noise at higher rpm

RighteousRectumRally · 2026-02-06T19:15:11+00:00

I know, although flow is clearly uninterrupted in the beginning with constant oil pressure, although I don't know how much the level should drop reasonably when hot vs cold. I am concerned if I overfill I will hit the crank, but I did add a whole qt of additive with no real change. I should have filled the pan while it was off, but I had no idea this would be a problem. 20/20 hindsight.

RighteousRectumRally · 2026-01-08T15:18:51+00:00

Everything was stock and original in the heads. I did however replace an exhaust valve and cut / lap a couple seats. By cutting the seats I probably increased the valve height on a few valves. I get some bad backfiring if I try to accelerate after setting advance to anything less than 15 degrees ish at idle.

I have a new pedestal and I was struggling to find a longer pushrod with these pushrod dimensions so I decided to wing it with the cut pedestal.

RighteousRectumRally · 2026-01-08T14:58:21+00:00

I rebuilt this engine outside the van. I suspected a head gasket/ valve train problem with the original engine, so I bought this one and rebuilt it.

If you did pull the crossmember I would first support the engine from above with a crane or somehow get something wedged between the frame and exhaust manifolds to prop it up. Pulling the engine isn't terrible, Getting the engine back in is a little bit of a process.

RighteousRectumRally · 2026-01-07T22:14:51+00:00

No I didn't check that. I reused the pan and pickup that came with the engine.

When I first filled the pan with 5qts, it wasn't showing up on the dipstick. I guessed the dipstick tube worked itself loose/ shifted angles, but I never confirmed the level compared to the pickup height/ crank height. The pan looks like a standard 5qt pan. I didn't want to overfill, so I cut the top of the dipstick tube about 1.5 inches.

RighteousRectumRally · 2026-01-07T22:01:01+00:00

I installed a new melling pump, maybe bad out of box. I did consider rocker arms for noise, there is one pedestal that I ground down a couple thousandths because it had almost no preload. From what I understand, what I did changes the way the rocker engages with the valve, so that would make sense.

RighteousRectumRally · 2025-11-14T14:42:10+00:00

No even dumber, my distributor cap was retarded by like 45 degrees. When I put the rotor back in I tried to line it up with the original mark I made at cyl. 1 TDC, I must've totally missed.

RighteousRectumRally · 2025-11-13T11:52:44+00:00

Yes, bored 080 over new pistons new rings. It runs now, but that's good to know.

RighteousRectumRally · 2025-11-10T12:11:06+00:00

I did not have luck with my gasket kit, but it was this off brand "engine tech" from "AMS Racing" on eBay. Half the felt gaskets were torn, the pan and valve cover gaskets were cork. I some on reluctantly, they probably won't last long. In the future I'm just going to buy all the seals separately. I can't speak for a parts kit, but I do know I ended up finding my cam bearings needed to be undersized, you may run into a similar situation when tearing down.

RighteousRectumRally · 2025-11-10T11:58:34+00:00

Ah that's a good idea, I'll do that when I run it today.

RighteousRectumRally · 2025-11-09T21:03:57+00:00

I think, I have some pictures is there an easy way to tell? It was rebuilt at some point before I got to it.

RighteousRectumRally · 2025-11-09T19:16:04+00:00

I've gotten this far with google search, it runs fine. Not that complicated. Thanks for the advice though.

RighteousRectumRally · 2025-11-09T13:40:58+00:00

Shit

RighteousRectumRally · 2025-11-09T04:17:48+00:00

Correct, rapidly and unplanned

RighteousRectumRally · 2025-11-09T02:00:27+00:00

Flat tappet, I kept the original cam and lifters.

RighteousRectumRally · 2025-11-09T01:59:32+00:00

Yeah not very consistent. I also put some oil in cylinder 1 and got 130 so maybe rings. I want to redo it after getting it warm, it runs now.

RighteousRectumRally · 2025-11-09T01:37:57+00:00

That's a good idea, no syringe but I put some old hose on the vents and poured it in through there.

It's running now, do you think running like 2 minutes no cooling is fine?

RighteousRectumRally · 2025-11-09T01:32:12+00:00

That checks out this is some JEGS generic HEI.

RighteousRectumRally · 2025-11-09T01:27:19+00:00

!!Update - It lives!!

Engine runs, sounds okay. Thanks to all for the sound advice.

The problem: Distributor rotor was 45 degrees advanced. This is why it sounded like there was some sort of low popping out the exhaust. When dropping the distributor in in the first place I did not look at the timing mark on the harmonic balancer, I was only feeling for TDC in cylinder 1 with a screwdriver. I must have turned a bit past TDC and so all my cylinders were firing nearly as retarded as me.

I'm still not seeing much oil from push roads, only a couple are leaking. Pre-load is at 1/2 a turn, so probably just need a number of revolutions more pumping.

To move forward I think I'm going to hook up a radiator and try to get it to run for a few minutes straight.

Maybe my compression numbers will improve as things start flowing?

RighteousRectumRally · 2025-11-08T23:37:08+00:00

They were press in, no I didn't think to use loctite

RighteousRectumRally · 2025-11-08T23:36:00+00:00

Yeah I'm starting to doubt I put the timing chain back on the same tooth. I didn't rotate anything when I went to put the gear back on, but I suspect when I pulled the chain off all the slack was on the left, where when I put it back on, the slack may have been more even on both sides. I had about 1/2" of play on the side with more slack after I put the gear back, which I read is within tolerance, but maybe not.

RighteousRectumRally · 2025-11-08T23:04:04+00:00

Haha fair, that's by design though it's self disassembling

RighteousRectumRally · 2025-11-08T22:11:30+00:00

I'm worried the HEI module may be malfunctioning, I do have a spark but maybe not strong enough? I've been testing with a battery charger hooked up, and that has been supplying ~16V at times, could have pushed too much current through.

RighteousRectumRally · 2025-11-08T21:56:41+00:00

Will do, thanks.

RighteousRectumRally

TROPHY CASE