how do you check pistion to valve clearance?

 

http://www.fordmuscle.com/fundamenta...ve/index.shtml

Here are a couple of ways to check, neither of which appear to be dooable with the engine intact.

 

i plan to purchase a set of AFR 165 heads - will i have to worry about piston to valve clearance and the length of my pushrods? my understanding is that they are a true bolt on.

67, 289 - 306

comp cam stud mount roller rockers

.500 lift.

 

So long as the heads are made for the same type of intereference setup as what your pistons are setup for you should be fine.

Interference is when the valves are open, if part of the piston tries to occupy the same space as the open valve at the same time.

Non-interference heads for non-interference applications vs. interference heads (have longer valves or shorter springs) and in some cases a different deck height.

You can make up for some interference by the type of cam you use and the pushrod length you choose, but then you lose some of the power you gain by adding the head in the first place.

If it's a true bolt on replacement then you shouldn't have to worry about it. You could always dry mount the head without the headgasket (no torquing of the bolts) and see/feel that the the open valves don't hit the piston(s) when you spin the crank. If you have clearance without the headgasket, then you're golden.

 

good to know, thanks.

 

If you change from your stock cam to one with a higher lift or longer duration you should check it. If your changing heads just put some play dough on top of one of the pistons, bolt your head on and roll the engine over by hand. Pull the head back off and measure the dough thichness where the valves hit it