Hemi valve lash

[moparmarks]

Have a Hemi with this mechinal roller cam.
Lift in .651 ex. .664
Dur. @.050 in. 273.25 ex. 279
Lobe center 114* installed 108*
What should I set the lash at for both cold and hot?
The blue print sheet says in .016 ex .020 but don't know if that is for hot or cold. Checking where it is at now cold it is much tighter.
Many thanks.

 

[Jerry Hall]

With heat everything expands, so my guess is that the cam specs are the cold numbers.

 

[rickseeman]

I've never seen a Hemi cam spec cold. You must assume that is hot. With aluminum heads you can set it .007" tighter cold and that will get you close. I haven't put anything together with iron heads in so long I don't know, maybe .004" tighter.

 

[gtx6970]

My cam card just for reference
But mine is solid lifters

But I cant imagine this specs is for a hot engine

 

[AR67GTX]

Are your heads steel or aluminum? Makes a big difference on aluminum head big block Chevies so it might on a Hemis too?

 

[moparmarks]

Indy aluminum heads

 

[steve340]

From what I know and have seen over the years camshaft manufacturers always specify HOT lash settings.
The lash obviously needs to be correct when the engine is hot.
Like Rick said if you want to set them cold depending on head material etc you reduce the gap used.
I will usually warm up the engine and take a valve cover off and check a couple of cylinders to ensure the cold setting was close.
I do them cold from there and look for any big changes in lash - no big changes all good.

 

[RemCharger]

I agree, need to find the hot setting, then figure out cold, and use it from there. I imagine trying to get to the valves before they cool off in a hemi would be " un fun"

 

[steve340]

Another way I have done it on an already running engine.
Warm the engine up and set the hot lash on number 1 cylinder.
Don't move the engine and allow to cool until the next day.
Measure the cold lash and set the rest to this setting.
Takes a bit of time but it appears to work OK. A thousandth tight or lose does not seem to make a lot of difference to power IMO.