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So the hole we were discussing is in the rocker arm where it contacts the lifter. As I understand it, the oil enters thru that little hole in the side (see lifter on left), then eventually exits thru the top. The lifter sits vertically (well sideways, actually), so I don't think the rocker has anything to do with the leak down.
These lifters for the 4.7L are the same brand and part number, however the one on the left is considered the improved version. Notice the smaller hole at the top. I guess the lifter on the left should keep a better pressure than the right.
Yes, I was thinking side hole and yes, oil enters the side hole. It exits the top hole, is forced up the pushrod and that is what provides oil to everything under the valve cover. But, what's weird is that the older style had such a large top hole to begin with, along with the tiny, tiny side hole. Both the top and side holes should be about the same size, and they should be about halfway between what the side hole and the smaller top hole are. At the bottom is a picture of a small block Chevy lifter for reference, and SBCs don't generally have problems with proper lifter oiling. If anything, a SBC is capable of pumping all of the engine's oil into the valve covers if the oil drainbacks aren't large enough. No idea if it would be possible to drill the small hole out a bit, but IMO (for whatever that's worth ) that hole needs to be a tiny bit larger. I did notice that the same lifters in the 4.7L are also used in Mustangs, which indicates that lifters are interchangeable amongst makes, so this makes me wonder if there might not be a lifter from another make that would work in the 4.7L that already has larger holes. I'll also point out that before actually trying any of this, discuss with a performance engine rebuilder, not a stock builder. A performance rebuilder would know better than I do about what lifter upgrades work with a 4.7L.
On bleeddown, when the engine shuts down the springs should collapse the lifters. Once they are collapsed, the oil's surface tension should be keeping oil from gravity draining out of the lifter for at least a couple of days. If the hole in the top is too large, then surface tension won't be enough to keep air from forcing its way in.
The noisy lifter isn't going to be due to the smaller top hole,, because the small side hole is the pessure restriction. My thinking is that there might be an issue with the lifter. It's possible for a new lifter to be bad out of the box.
04-05-2022 | 01:19 PM
) that hole needs to be a tiny bit larger. I did notice that the same lifters in the 4.7L are also used in Mustangs, which indicates that lifters are interchangeable amongst makes, so this makes me wonder if there might not be a lifter from another make that would work in the 4.7L that already has larger holes. I'll also point out that before actually trying any of this, discuss with a performance engine rebuilder, not a stock builder. A performance rebuilder would know better than I do about what lifter upgrades work with a 4.7L.