valve lash setting
 

I just bought a new set of AFR heads, and as i was reading there directions, It said to run the valve lash .006 tighter than normal. I am running aluminum heads on a iron block.
i have never heard of this, is this true??????

Cold valve lash with aluminum heads will measure about .006 greater when they heat up so when the engine is fresh you set the lash at .006 tighter cold to get started. Always lash the engine hot for an accurate final setting. The head will expand at different rates along the head due to thermal mass and unequal heating which is the condition that the engine runs in. Always do the lash and check it at the same temp every time. The hotter temp that you set them at the tighter they will be when cold.
Bruce

X2, thats also why you need to let your engine heat up before you start ripping the throttle....

Just set them cold.Once it warms up check them and see how much they changed and then do the math....I set mine at .016 cold and when it warms up they are .022-.023 . Iron block aluminum heads.

X2

X3

ok then my cam said to adjust mine at .025 in and ex is that way to much if it expands that much?????????solid roller steel on steel

i always have just brought it to temperture and set the valves,never had any problems. i did not no about the .006 tighter for alum heads.
30 years of doing this and still learning. no wonder i am still slow !!!!
Thanks for the imfo-----

Your instructions were for setting them cold. Aluminum heads grow more than steel heads. They're just giving you a round about figure to set your valves cold. Like it was said earlier set your lash at .024 to .026 hot or whatever your cam recommends. Then check after your engine has cooled off, that will we your variance, and it will probably be close to .006.