Rage

Ray,

Is there another lifter currently available that will work properly in a Merc 496HO engine besides the stock Merc/GM lifter or the Comp Cam direct replacement lifter?

Raylar

Rage:
You can contact Bob Madera about the Morel lifters he has available.
The stock lifters are the same as any Gen5, or 6 BBC hydraulic roller lifter.

However in all the 496's we've done over 8 years the only time we ever lost a hydraulic roller lifter was when there were other issues in the engine, ie:
oil flow or pressure problems
Bad material or lobe on the cam (most common)
Bad lobe profile on aftermarket reground cam
extremely heavy (over poundage) valve springs or valve springs that were to light on poundage where they allowed the valves to float and pound the roller out of the lifter

I don't think just changing your lifters is an automatic fix as you may want to find the source of the problem before you continue if you can.

Best Regards,
Ray @ Raylar

Rage

Thanks for the information Ray. I am not assuming that the lifters are the problem but trying to be ready in case I find that they need to be replaced. Do you have any feeling as to if 413 pounds max valve spring load has been a problem for the stock OEM 496 lifter when everything else is OK?

Best Regards,

Bill

Raylar

That open spring pressures is not a problem on stock hydraulic roller lifters, but the possibility of coil bind or not enough stem length or spring pocket depth on the valve and have it bounching off the valve seal and such can set up harmonics that can damage lifters.

Best Regards,
Ray @ Raylar

Rage

Thanks again for the information Ray.

Rage

I just learned that the Crane lifters for this engine are again available.

Raylar

I would not use them, end of story!

Best Regards,
Ray @ Raylar

Rage

Yep. Placed the order already.

Rage

FYI the Crane lifters have an unshrouded roller versus the stock lifter's roller is fully shrouded by the lifter body. At max cam lift this roller slot in the Crane lifter body when at max cam lift creats a ~0.030" opening for oil pressure to escape from the lifter's oil galley.

With the stock GM lifters and cold oil I previously got 55 psi @760 rpm and 75 - 80 psi @ WOT. When the oil gets real hot after extended WOT running the oil pressure previously dropped down to 25 - 30 psi at idle and 50's at WOT with the stock lifters . Now I am getting 30 psi at idle. Assuming the same ~25 psi lower pressure at WOT I would now be only at 50-55 psi with cold oil and assuming similar pressure loss with hot oil it would be at 30 psi or lower at WOT. Not good.

69-CHVL

Could you explain, or is there a link or something we can look at? I saw what Rage posted...I never experienced a oil pressure loss myself .