Valve / Piston clearance, Is there an easy way?

[Hemlock]

I was considering changing the cam in my new 347 to a slightly taller one and changing the intake at the same time. I was considering a Torker or Air Gap RPM (not sure yet, suggestions?). Anyway, is there an easy way to check the valve clearance on the new cam without taking the heads off the engine? I am currently running an E303 atm but was thinking about going with a cam around .550 gross lift. My SRP pistons are forged and have some pretty healthy valve reliefs in them and the guy that did the machine work said I still had a little room for more cam but of coarse when I called him last weekend he said he didn't write down how much you would think with how much I paid him he would have jotted it down LOL.

Thanx in advance for helping,
Robert

[82mustang]

i've heard of sticking a piece of solder down the spark plug hole..just hope you pull out the same amount you put in!

~Mark~

[Mike Croke]

The short answer is no. You have to pull the heads and phyiscally check.

The longer answer is piston-to-valve interference will not happen at peak lift numbers so the peak lift of the cam isn't enough information. During the intake opening event, the valve starts to open when the piston is still coming up the bore pushing out the spent exhaust gas. The piston reaches top dead center and as it starts back down to draw the air/fuel into the cylinder, the intake valve continues to open and chases the piston down the cylinder. This is where the interference occurs typically when the valve is only about halfway open. That's why peak lift is irrelevant.

[MurPHy]

Mike Croke nailed it. Look at ramp speed, that'll be more indicative of how risky it will be to run it without claying it than looking at total valve lift will be.

Pull a head and clay it, that's the only way you can be ABSOLUTELY SURE you won't bend a valve. Keep in mind most like to clay it without a headgasket aswell, so that's an extra .038-.050" or so of clearance right there, depending on gasket thickness.