# Question about PTV with my new Cam and Heads



## SlowGoat (Apr 29, 2011)

I have a 2006 6.0 liter. Just Ordered a new Comp Cam and Trick Flow heads. I am not really worried about PTV but I just would rather be safe than sorry. My heads are 225cc's with 13.5 degree valve angles 65 cc chambers milled to 63cc chambers. The cam is 237/244 .610/.595 Lift and a 113+3 LSA I have LS7 Lifters 1.7 Yella Terra Rockers Using Factory Head Gasket and obviously am measuring for the pushrods. 
Should I be worried about my PTV Clearance? Any Help would be great thanks so much.

PS all stock lower end

Thanks


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## mebuildit (Jul 29, 2011)

I always have checked my PTV clearances. It only takes a little bit of your time vs. hurting the engine later.
Just put a few little pieces of clay on the piston valve cutouts and roll the motor over several times. Do not just roll it over once!
Pull the head measure the clay and add a little bit for stretch. Overall, that will give you some peace of mind.


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## svede1212 (Nov 1, 2005)

I should add that the best way is to spray the clay with some spray to chill it before removing it. It will make the clay firmer and easier to get out. Cut across the thinnest part with a razor blade and measure the thickness at the thinnest point. The exhaust should be .100" or more and the intake .080". Because the piston is chasing the exhaust valve as it's closing the exhaust is the most important one and why you want more clearance there. On the intake that valve starts coming down as the piston is going down too. You really need to measure as it isn't the lift of the cam but the duration and timing events of the cam that determine clearance. The cam could have 3" of lift if it occurred when the piston was at the bottom of its stroke. It's the opening and closing of the valves when the piston is near the top that can cause contact


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