Hello everybody finally decided to join instead of just lurk. I'm about ready to start my 5.3l project and curious if anyone else is running a similar set up with no ptv issues.

lm7 with PRC 5.3l stage 2.5 heads 59cc
tsp 218/220 .600/.600 112 LSA
stock bottom end with factory dished pistons

Im wondering if .040 or .041 headgasket will work before I order?

thanks in advance for any insight.

 

It's best to measure to be sure, however, it *should* be fine. PTV issues are more of an issue with longer duration cams.

You're also going to different pushrod's.

 

What’s the advance on the cam?

 

 

THIMK about cam lift.

Exh lift begins at BDC more or less and ends more or less at TDC, int lift is the same except begins at TDC and ands at BDC. Max lift for each occurs with the piston halfway down in the bore.

Lift isn't what creates PTV issues.

Problems come from DURATION: the amount that the exh valve remains open as the piston passes through TDC, and the amount that the int is already beginning to open as the piston passes through.

A cam with that little duration shouldn't be a problem if installed at any sort of normal intake centerline. (i.e. not advanced or retarded by more than a few degrees)

However it only takes a few minutes to measure, and since every combo is different, that's the only way to ever know for sure anyway.

 

Always measure but I ran a l33 with prc 2.5 milled .17 with .40 gaskets and a 223-226 110+4 cam and I was fine.
duration and lsa effect ptv

 

Sorry for the late reply and thanks for the info. I haven't decided on cam advance yet Probably no advance or +4. I will for sure be measuring ptv just checking to see if what I have planned is feasible with that thin of a gasket.