verbs

I'm trying to figure out what my P/V would be for my heads with 2.02/1.55 valves and 5.3L heads milled .010.

I had .085 clearance with a TR 230/224 .576/563 110.8LSA, so I'm wondering what I'll have with the GX5-2 cam?

Please tell me the size of your valves, cam LSA, how much your heads are milled, if you run aftermarket rockers, and the clearance you have.

Thanks guys!

Scalpel

iTrader: (4)

Verbs, how do you measure PVC?

BergerMan

I had .035" clearance with my G5X2 and 5.3L (2.02"/1.57") heads (unmilled). I cut .055" reliefs in the pistons to get me to .090". I just replaced the 5.3's with a set of PP LS6/LQ9 (59cc) Stg2 heads and I had about .154" ptv clearance (but the pistons were already cut). So if you do the math and subtract the .055" that I cut from my pistons, I would have had .100" ptv with the Patriot heads and the G5X2 without cutting reliefs. that is what makes these heads so attractive to the big cam guys that don't want to mess with cutting reliefs.

Since you have the G5X2 I can tell you how to measure PTV without using the clay method:
#1 Remove the springs from the intake and exhaust valves on the #1 cylinder.
#2 Bring the #1 piston to exact TDC.
#3 Install this head using an old head gasket and install a few bolts and snug them up, no need to torque them.
#4 Setup a dial caliper to measure on the tip of the valve stem. Hold the valve up against the seat and zero the caliper.
#5 Push the valve down until it touches the top of the piston. Read the caliper and record how far the valve dropped.

EXAMPLE
G5X2 has an intake valve lift of .120" when the piston is at TDC (direct from Lou).
Measured valve drop = .220"
Minus the .120" lift @ TDC
Equals .100" PTV Clearance

verbs

Thanks Berger, I had a hunch that was the case.

Scalpel

iTrader: (4)

That's a really easy method as long as you the the intake valve lift. Thanks man.

gomer

iTrader: (13)

I'm missing something after reading the post above... How can you have two sets of heads.. both at stock deck height (you said the 5.3's were unmilled) and not have the same P/V clearance? Or atleast somewhere close. There is a .065 difference between your unmilled 5.3 numbers and your unmilled LS6 style numbers.

JF WS6

The different factory heads (LS1/LS6, 6.0, 5.3) have different compression ratios and ports in stock form, they are not all exactly the same. So you might have clearance with a set of LQ9 heads but not with 5.3's which are of a slightly different design and higher compression.

Another thing is with different sized valves. A larger valve will obviously give you less clearance. He may also have smaller valves in the LQ9 head.