I have heard of problems running the factory style hydraulic roller set up with cams that have alot of lobe lift and smaller base circles.

I have heard of oiling problems and the possibility of the lifter dropping below the lifter guides...which would be castistrophic.

Cam in question is a XR288HR .360 lobe lift,.540 at the valve with 1.5's. Base circle is 1.15 which is standard for this cam.

Thanks!

 

Yes that would indeed be catastrophic.

That part of the block isn't machined with any particular precision, so there's no "magic" lift at which you will start to have problems. I.e., there's no way somebody can sit here and tell you that it's always fine at .561", but they will fall out at .562", in EVERY block. Just ain't so.

At .540" of lift, you're just entering the "danger zone". If YOUR PARTICULAR BLOCK has the flat place for any pair of lifters machined a little bit on the tall side, then you COULD be getting close to the limit.

Only way to know is to put it together and check. If you spot a problem on any lobe, buy the $$extra tall link-bar lifters$$.

 

You got that right,about $500 for the Cranes.

What would you say would be the safe minimum amount in thousanths before dropping below the guide?

 

Just thought I would post back and let those interested or doing a search know that on my particular factory hydraulic roller ready block, the top of the lifters is flush with the top of the guide when the lifter is on the base of the lobe. I have the entire thickness of the lifter guide as security.

The cam has a .360 lobe lift and is on a 1.15 base circle.

 

When I put mine together, I was also worried about this, but mine also ended up having lifter within the entire thickness of the guide. Lift at the valve was .570 (0.356 calculated lobe lift) (268 XFI) with 1.6 rockers.