Engine: Lifter Clearance

[swaim43]

[Tom Bredehoft]

I'm no authority on the oiling of lifters in Studebakers, but since they are solid, they probably are oiled by 'trickle down' not pressure and would not be a source of oil pressure loss.

I hope someone will confirm or refute this.

[tbirdtbird]

I doubt the lifter bores are the prob. What was the pressure before the rebuild? I am gonna let someone who knows more about this oil pump/relief valve answer this one. Technically 5 psi at idle is the minimum you need, but on a new rebuild it should def be higher, since now you have no safety margin as the engine wears

[whacker]

Did you check the cam bearing clearances? I would suspect those before I would suspect the lifter bores. Anyway, 30 PSI at power and 5 PSI at idle should be OK. I've driven some that were worse than that, although not right after a rebuild.

[JoeHall]

Worn or goofed up lifter bores can absolutely cause low oil pressure. Each one has an oil hole where it receives oil under pressure. Plus, there are 16 of them, so it doesn't take much to cause pressure drop. I don't know what the clearance is, but I am guessing .001-.002".
Joe H

[Charlie D]

The shop manual for the 1955 259 V8 says the oil goes to the valve lifters under pressure. The lifters are supposed to slide into place under their own weight. It also speaks of oversize lifters being available in .001 & .005. If you can find the .005 oversize lifters they may fit right in what was given back to you.

Charlie D.

[Warren Webb]

I cant understand an engine builder going thru all that cleaning & then let it sit out in the open for 2 months! With no lube to prevent the rust in the first place. Whenever I hear of poor oil pressure after a rebuild it seems like the most overlooked part is the pipe plug inside the distributor opening.

[Tom Bredehoft]

Each one has an oil hole

I stand corrected. Thank you Joe.

[JoeHall]

I cant understand an engine builder going thru all that cleaning & then let it sit out in the open for 2 months! With no lube to prevent the rust in the first place. Whenever I hear of poor oil pressure after a rebuild it seems like the most overlooked part is the pipe plug inside the distributor opening.

If someone were to leave out the 1/4" pipe plug inside the distributor opening, or in any one of the other three locations, the engine would suffer catastrophic pressure loss, i.e. none, zero, nada. That is the end plug for one of the two main arteries. Even leaving out one of the half dozen or so, 1/8" pipe plugs would result in the same catastrophy. I once had an oil gage pressure hose let go (the one coming off the right rear head), and oil pressure dropped to zero. That was on the freeway around Los Angeles. What is different in the many plugs is that some are inside the engine, and simply dump oil back in the pan, and some are external and dump oil all over the everything, like a garden hose.

Joe H