[Steve C.]

I had a lifter fail in a BBC and broke the block. It was a comp cams roller and the recomended lash was .028 and .030 so that is what I ran..I thought that was too loose but figured the cam company knows more than me ..well now I am paranoid .My new engine has a Crane grind and the cam card said .026 and .028..but to be safe I set them at .017. My question is...will this hurt anything? I used to think that the recomended lash was just whatever made the best power on the dyno...but since reading this board the last few months,I gather from the posts here,that the lobes on the cam are designed for a certain lash....that it isn't just a tuning thing.So, what effect(other than making the engine think it has more cam) will running a considerable amount less lash than recomended have?

Answer......

It depends on how the clearence ramp was designed. It'll either have no effect on valvetrain stability, or it'll help. It won't hurt anything but performance.

It's not the tightness of the lash, it's the velocity of the cam at that point that dictates how hard the lifter hits the cam. You can have a cam designed for a looser lash that has less velocity at the lash point then a cam designed for a tight lash.

Source: http://speedtalk.com/forum/viewtopic.php?t=8265



( Does this relate to the typical .006" lash used on the Hybrid set up with the solid roller lifters ? And a fwiw, my comments here regarding valve spring pressure are for the most part regarding the solid roller set up not using hydraulic roller lifters. Nor do I have a issuew with the Crane spring as long as it measures correct and used in conjunction with adequate pressure for the intended use )


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