To make a long story short my pistons are .058 out of the hole. Evidently my block had been milled before. Anyway... my builder told me that I could just use a .072 gasket and that would still give me an acceptable c.r. My problem is I am thinking my ptv will be much smaller? Am I right here? I plan on running ~240 intake x ~252 exhaust cam. Should this fit with an unmilled set of LS7 heads? If I get a valve job on them will that give me more valve drop? Oh yeah, my pistons are -7cc diamonds. The valve cuts are 15 degree though. I probably need to get that recut huh? Any help would be greatly appreciated.

 

Wow. Are you positive it's .058 out of the hole? Most LSX shortblock assemblies have the piston above the deck, but not that much.

 

That is what he told me. i know the norm is .007-.012. Like I said evidently the block had been decked before.

 

I would be more worried about the pistons hitting the heads.

 

He told me by using a .072 gasket that would keep that problem away.

 

That's only like .014" quench area, which is extremely shallow. Most people will recommend no less than .028" for a street LS1 and you're at half that. Hmm...

 

Wow..No way the block was milled down that far.

A more likely senario is the wrong rod length/piston pin height combination.

better check the pin height info on the piston box, measure the pin height on the piston. Then do the rod info, I think the answer will be found.


Dave

 

The shortblock is put together and he told me I wouldn't have any problems as long as I used a thicker gasket and used a bigger chamber on the heads. By the way how thick can cometic make gaskets before they become a problem?

 

That's pretty close. Rod/pistons are going to grow at temp and you might have some real problems.

 

4.125" Stroke Crank with pistons for a 4" stroke crank would do that also.

 

Just got off the phone with Joe. Good news!! The pistons are only out of the hole .030. Much, much better.Now I can run a crazy *** huge bitch of a cam and still have decent Ptv. Even with a 70 cc head and a .072 gasket my compression will still be over 11-1. God, I feel so much better!!