1993 Yukon crate motor hydraulic roller lifter cleaning and adjustment journey - (Solved)

[Schurkey]

it's more the question of why they tend to want to be noisier at startup with different preloads if that makes sense.

OK. From that perspective, I'd want the plungers adjusted near--but not at--the bottom of their travel.

That way, as the lifter plunger bleeds down from valve spring pressure, it can't go very far before it's at the bottom of it's range. And being adjusted near the bottom of it's travel, it'd take minimal oil to pump it back up again when the engine is started.

Adjust the preload too tightly, the plunger is at the bottom of it's travel, and the valve can't shut. Engine runs terrible, or maybe not at all.

what do you mean travel?

The lifter plunger has a limited movement within the lifter body. At the top, it runs into the snap-ring, and it can only go down so far before the check-valve hits the inside of the lifter body. So again, some lifter plungers have extremely limited range of motion, and others have heaps and bags of travel.

 

[scott2093]

OK. From that perspective, I'd want the plungers adjusted near--but not at--the bottom of their travel.

That way, as the lifter plunger bleeds down from valve spring pressure, it can't go very far before it's at the bottom of it's range. And being adjusted near the bottom of it's travel, it'd take minimal oil to pump it back up again when the engine is started.

ah..really?

So that may be why there are like 6 threads showing on the rocker studs before I ever touched the lifters and now there are 3 at most?

I swear things started feeling different/worse with more preload but that was before I cleaned them....

I'd say my lifters have heaps of travel...I could make noises by bottoming out the lifter when I was pumping them up by hand until they got all of the air out... I had plenty of slack to get that much momentum...

guessing you can't deduce by the way they look?

 

[Schurkey]

Refresh my memory...is this a rebuilt engine? Does it have vented oil gallery plugs at the front of the block?

GM started putting ventilated plugs in the SBC oil galleries; and other engine families have had one or more ventilated oil gallery plugs since Fido was a pup. Most guys say it's to "lube the cam chain" but the real reason was to quickly bleed air from the lifter oil gallery so the lifters don't clatter. The air blows out the vent instead of being pushed through the lifters.

Most soft plug kits don't supply the ventilated plugs. But they are available in various sizes.

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[scott2093]

Refresh my memory...is this a rebuilt engine? Does it have vented oil gallery plugs at the front of the block?

It's a crate motor..638 block iirc...
Not sure where the vents are? If you mean, where I can reach in and touch the timing chain via 2 holes on either side of the front inside the valley , then yes...but there are no plugs...
There are other holes too but I'm not sure what you are describing...

 

[Schurkey]

In the SBC, the lifter gallery plugs are cup plugs. On the big-blocks, they're thread-in plugs. They're the "mickey mouse ears" just above the cam in this photo of an older big-block. The plugs in this photo aren't vented.

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[scott2093]

 

[scott2093]

That doesn't sound like something good if it's missing? Is there a way to check with leaving the intake on? I can fish the scope somewhere?
The only plug I know of is that one I thought may be leaking just below the cts area under the china wall ledge..?

 

[termite]

That doesn't sound like something good if it's missing? Is there a way to check with leaving the intake on? I can fish the scope somewhere?
The only plug I know of is that one I thought may be leaking just below the cts area under the china wall ledge..?

To see the plugs Schurkey is describing, you'd need to have timing cover off, and maybe even cam chain sprocket. Perhaps you could snake your scope/inspection mirror in from the lifter valley and be able to see.

 

[scott2093]

To see the plugs Schurkey is describing, you'd need to have timing cover off, and maybe even cam chain sprocket. Perhaps you could snake your scope/inspection mirror in from the lifter valley and be able to see.

Only place I remember feeling was where I could touch the timing chain on either side from inside the valley. I could also see chain and sprocket with scope when I had valley open. I believe it was the areas in this screenshot of a video I got lucky enough to scan past but am not 100%.. I'm not going to open the intake hopefully for some time and don't think fishing through the heads after removing valve covers would work. Maybe. It's easy enough to peek in the valley and I think there is access right there via an open channel next to #2 fi...But that would be like trying to open a car lock with a coat hanger for sure...

 

[scott2093]

I went to adjust the lifters again and tried to get a shot of the area in front of valley I was talking about. Not much to see regarding any plug.

I'm actually now at 1 and 3/16 turn preload. Runs good and quiet. Don't like the idle as much. Could be placebo I guess. And performance seems different. Not as exciting. More steady sounding tone at idle too. But maybe I'm imagining.

Probably take it back to 3/4.
Honestly it only tapped twice at startup after sitting overnight when preload was at 1/2 turn plus 3/16 and ran great..but it was on flat ground all night..I can live with a couple of taps at startup........ As long as it doesn't tap for a minute....