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

[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

[Rich Biebel]

The correct solution to me, is one of two choices. Machine the lifter bores for bronze sleeves to eliminate the grooves and use the direct lube lifters. OR....Use the block as is and buy different lifters without the holes. Either option is gonna cost a good bit. Using restrictors is worth a try at this point.

[Glenn Briglio]

Might want to start with oil restrictors with .060 hole in them on engine stand and prime engine to see results up top.You can always make the hole bigger.

[Nmbr1GMfan]

Originally Posted by Glenn Briglio

Might want to start with oil restrictors with .060 hole in them on engine stand and prime engine to see results up top.You can always make the hole bigger.

That's the plan Glenn, thank you.

[Kenny McCoy]

Originally Posted by Glenn Briglio

Might want to start with oil restrictors with .060 hole in them on engine stand and prime engine to see results up top.You can always make the hole bigger.

I would start at .030 with thin oil

[Dissident]

Todd, Autumn, and those interested,
FWIW - All my calculations, estimates, and comments were based on the kinematic viscosity of hot (190F-200F) 30W oil. The leakage flow with lower kinematic viscosity would be higher numbers.


Being an oil patch brat, I have rather strong opinions against using 0W lubrication in engines as I was taught to err on the side of reliability. And I fully realize your experiences may vary, but you can't win if you don't finish.


Regards,
HB2
Dissident

[Nmbr1GMfan]

Originally Posted by Dissident

you can't win if you don't finish.

Or never get started Thanks for the insight.

[Nmbr1GMfan]

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. 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

This is an eye opener!