H-I-J '76 Nova re-fit.

[Rich Biebel]

Good...…

I think you have it right.....to much oil up top maybe and volume being bled off various places......starved the bottom end for enough oil....

I've used the lifters with the oil holes on a bracket engine and had no problems using them.

The race filters are less restrictive than a std filter...usually....

Luckily you caught it before it ended up real bad...….

[Nmbr1GMfan]

Originally Posted by Rich Biebel

Good...…

I think you have it right.....to much oil up top maybe and volume being bled off various places......starved the bottom end for enough oil....

I've used the lifters with the oil holes on a bracket engine and had no problems using them.

The race filters are less restrictive than a std filter...usually....

Luckily you caught it before it ended up real bad...….

I really want to keep the EDM lifter, I think restrictors and a step up from the std volume pump will do it.

[Hacksaw]

Originally Posted by Nmbr1GMfan

I really want to keep the EDM lifter, I think restrictors and a step up from the std volume pump will do it.

Understandably you are trying to correct a problem but stepping up the oil pump will also take more hp to drive it. Controlling the volume is the answer.

[Rich Biebel]

The lifter bore cam oiling modification I am not clear on what was done. If it is possible to undo that ? If a slot or channel was machined I assume it could not be returned to stock. If a hole was drilled you might be able to plug those holes. The direct feed lifters bleed off a lot by themselves right on the cam.

[Glenn Briglio]

You said there was a lot of oil coming up thru solid lifters. How did you verify that? If so you might need restricted oil hole pushrods. Or oil restrictors in block

[Nmbr1GMfan]

Originally Posted by Glenn Briglio

You said there was a lot of oil coming up thru solid lifters. How did you verify that? If so you might need restricted oil hole pushrods. Or oil restrictors in block

The old lifters put very little oil to the rocker, these are like a flood at the rocker. I could tell a huge difference when just pre lubing. I've been told restrictors drilled to .0120 for EDM lifters and it will be easy to swap them if necessary without opening the engine up.

[Nmbr1GMfan]

Originally Posted by Rich Biebel

The lifter bore cam oiling modification I am not clear on what was done. If it is possible to undo that ? If a slot or channel was machined I assume it could not be returned to stock. If a hole was drilled you might be able to plug those holes. The direct feed lifters bleed off a lot by themselves right on the cam.

Lifter bores are machined with a slot, I could bush them but I'm done spending $$$ on a junk block. I thought about returning to a non EDM lifter but I'm worried about the cam with high spring pressure.

[Nmbr1GMfan]

Originally Posted by Rich Biebel

The lifter bore cam oiling modification I am not clear on what was done. If it is possible to undo that ? If a slot or channel was machined I assume it could not be returned to stock. If a hole was drilled you might be able to plug those holes. The direct feed lifters bleed off a lot by themselves right on the cam.

Took a picture while I was there today.

[Dissident]

Todd,
Being a data kind of guy, I ran some quickie calculations for the potential flow (internal leaks) of the EDM lifters and the groove thing in the lifter bores. I used 50psi as that is the pressure number you mentioned.The EDM lifters will flow approx 0.0371gpm (each) at 50psi. The grooves in the lifter bores will flow approx 0.264gpm (each) at 50psi. Doesn't sound like much until you toss in each number times the 16 leak paths. Total flow at 50psi = 4.8176gpm! WOW.

At that rate of flow, 5qts (1.25gal) will cycle very quickly. The grooves themselves go through 4.224gpm so I suspect that is the major offender and caused the earlier ugly bearings. Seems like the grooves need to be rendered useless, but I suspect that your engine shop guys have already suggested that.


I realize that I might be full of soup in this assessment, but I think it is very close to the correct analysis.



Best of luck solving the problem.



Regards,
HB2
Dissident

[Alan Nyhus]

Originally Posted by Dissident

Todd,
Being a data kind of guy, I ran some quickie calculations for the potential flow (internal leaks) of the EDM lifters and the groove thing in the lifter bores. I used 50psi as that is the pressure number you mentioned.The EDM lifters will flow approx 0.0371gpm (each) at 50psi. The grooves in the lifter bores will flow approx 0.264gpm (each) at 50psi. Doesn't sound like much until you toss in each number times the 16 leak paths. Total flow at 50psi = 4.8176gpm! WOW.

At that rate of flow, 5qts (1.25gal) will cycle very quickly. The grooves themselves go through 4.224gpm so I suspect that is the major offender and caused the earlier ugly bearings.

Regards,HB2Dissident

Actually, I think your figures are pretty close. Lifter bore clearance is also a component. Todd mentioned that one of the lifter bores had two grooves in it. -Al