IQ52 said

In my experience yes. Aluminum Edlebrock, Indy, Trick Flow, 440 Source, Speed Master. 10-12 years ago (maybe more) I found out about it reading a Chevy engine build article using Edelbrock Aluminum heads. Then the Edelbrock Tech Line told me their heads wouldn't do that when I was purposely testing and measuring the valve lash on a set of Edelbrock 440 RPM heads. From cold to hot I was seeing a +.005"-.006" change in lash. Never consulted Edelbrock's Tech Line after that.

And by-the-by, with aluminum block and aluminum heads I tighten the cold lash .010"-.012" from the hot lash setting. Gets a little dicey with a very tight lash cam.

Click to expand...

Bewy said

To me, 0.006" is a lot to take out of the lash for alum heads. My experience has been about 0.003".

However, this is so easy to check, it beats me why more people do not do this simple test that will give an accurate number for their combo.

Have your tools ready. Get the engine to operating temp & then switch off. Quickly remove a valve cover & find a loose rocker. Measure the lash & record it. Come back in the morning when the engine is cold & re-measure. You now have your hot-cold difference.

Click to expand...