aluminum heads with solid roller cam

[71monteme]

this question is for you guys running aluminum heads and solid roller cam. my cam spec a .030 valve lash hot. i did it cold to get the engine running. on the iron heads the valve lash cold and hot were only a few thousands different. so i usally set them at .028 and forget about them, how much of a different does aluminum makes and which way does it go- make the lash tighter or looser.

thanks.

 

thanh

[Mike 57]

My heads seem to be about .006 tight when cold. I also noticed a long time ago that cast iron were a little loose when cold just about .0015 to .002 probably the difference between the cast iron and steel pushrod and lifter expansion rate.

[wallaby]

 

For setting warm lash specs on a cold engine, Crane says add .002 for iron head and subtract.006 for aluminum.

Here is the page:

http://www.cranecams.com/pdf-tech-tips/mech-lift.pdf

[71monteme]

thanks for the info page. will be working on the motor this weekend. i'll post how close those figures are on that page.

 

thanh

[71monteme]

well, did the hot lash on the motor at 30. let engine cooled overnight and remeasure lash. it was at 25-26 so the crane cam page was pretty close. i run aluminum comp roller rockers for reference, hope some one can use this info.

 

thanh

[wallaby]

If you're using a computer program to evaluate your combo, don't forget to subtract that .030 from your valve lift specs.

[680HPStroker]

I always set the lash on a solid roller cam to the spec on the cam card your cam manufacture supplies with your new cam. There is no one fits all setting. There is a reason why the manufacture gives you the spec they do.