exhaust valve clearance
 

Hello to All,
I'm not a engine builder by trade and was mocking up my engine the with the head and gasket bolted on using clay on the piston with a very lite spring. I pumped up a set of lifters and measuring the push-rod for lenghts . I removed the head and measured the exhaust valve clay clearance which was between .080 and .085 , the intake was fine did not hit the clay. What is the normal valve to piston clearance. Thanks Jeff

minimum i run is .050, so you should be fine

I normally try to stay at .100 on the exhaust and .080 on the intake. All this matters on how aggresive the cam is, and what type. Also how eifficent the springs are. Have you degreed the cam in? If you advace it, you may be able to gain on the exhaust clearance. Hope this helps.

Jeff,
I am a chicken and also like to see .100 on most engines. Also, I dont know if I would trust a pumped up lifter, even with a light spring. If you have an adjustable pushrod, find a small washer that will sit on the top of the lifter and sit the pushrod on that instead. I actually have a drawer full of various lifters that I have "modified" to make them solid for this purpose.

The other thing that a lot of people do not pay attention to is the clearance around the edge of the valve in the valve relief pocket. You can slice the clay into wedges and look at this pretty easily. I like to see at least .060" or so clearance around the edge. This is usually only an issue with intakes on a Big Block

I would also have to double check to see if the cam is installed properly. Usually Big Blocks are exactly opposite ... the intakes are close and the exhaust has plenty of room. Did you use a degree wheel to check the camshaft ?

Bill Koustenis
Advanced Automotive Machine
Waldorf Md