I have had my heads milled and I am using a thinner than stock head gasket I am I wondering if I will need shortened pushrods? The heads have had about .012" taken off and the head gasket is the Impala .029" instead of the factory .051" that comes on the F-body's. I am going to get them checked but I just wondered what happens if they are the wrong length? Thanks.

 

Roller will not be centered on the tip of the valve stem... increases side loading on valve guides, wears them out sooner.

 

wouldnt you need longer push rods????

 

Your changes may or may not be enough to be a problem depending on cam, rocker ratio, etc. But it can be checked using an adjustable push rod made for such purposes. Assumming you have hydraulic lifters, you'll need to install a couple of "dummy" valve springs of only a few lbs. of pressure and then just observe the distances that the tips of the rocker travel throughout a full cycle from both directions from the center of the valve stem's tip as well as insuring that it's centered at rest. Adjust the pushrod length until things look ideal, then measure it's length and order accordingly. This is very straightforward with roller tips, I've never actually done it with stamped rockers. It may not be as easy by observation with them. I would just get slightly shorter pushrods in that case. Something close to equivalent of the distance you've brought the the valve stem's top closer to the cam's centerline should keep everything hunky-dory.