Need more P/V clearance in a BB mopar

[ss3011]

What method did you use to figure out your clearance ? Clay with full valve springs , or dial indicator with a light checking spring ?

[Larry Hill]

Use more deck clearance and keep the gasket thin. You will need about .035 '' total to keep pistons from contacting head. Have P/V clearance through the range of adjustment, so you can roll the cam forward or backwards without bending stuff. Exhaust valve will like to make contact in split overlap.

[Glenn Briglio]

Having the correct cam timing is more important then losing a half a point of compression.

[GallopinGhost]

Checking springs, with an indicator on the retainer

I've already moved the cam around to give me the most intake clearance, which has been the biggest problem, and still have around twice that amount of exhaust clearance.

Piston is .010 in the hole, spec is .004. I'm leaning on leaving the valves alone and using whatever gasket gives me the clearance needed. Those 2 together should give me the .035 Larry mentioned.

In hindsight, I should have gotten a smaller cam so I could keep some compression........

[Chevy55]

Cut the valve face a few thousands.
Also the cam could be ground to twink the duration, you won't lose compression and horsepower loss is negligible.

[ss3011]

Indicator method is good , but usually gives the closest value . When the real springs are used the clearance will be greater . Would be nice to be able to run the cam advanced , but that would be based on dyno testing .

[Glenn Briglio]

Originally Posted by ss3011

Indicator method is good , but usually gives the closest value . When the real springs are used the clearance will be greater . Would be nice to be able to run the cam advanced , but that would be based on dyno testing .

As Russ says, check with actual spring pressure. You'll have more p to v clearance.

[GallopinGhost]

I think for now we'll leave the valve job as is, I'd hate to lose anything there. I really just need to decide how much to deck the head. Once I get the head from the shop, I'll check it with race springs and see where it's at. Then I'll just get a gasket that will give me what is needed. This project is taking forever and I just want it on the track. Next winter I can do some of the trimming of the valve head and maybe re-grind the cam, hopefully that will enable me to then get a thinner gasket and get some of the compression back. thanks all

[Glenn Briglio]

Originally Posted by GallopinGhost

Checking springs, with an indicator on the retainer

I've already moved the cam around to give me the most intake clearance, which has been the biggest problem, and still have around twice that amount of exhaust clearance.

Piston is .010 in the hole, spec is .004. I'm leaning on leaving the valves alone and using whatever gasket gives me the clearance needed. Those 2 together should give me the .035 Larry mentioned.

In hindsight, I should have gotten a smaller cam so I could keep some compression........

Done it both ways, more compression and less than ideal cam timing and vice versa. Cam timing always more important than compression.