guy at work just bought 350 for his bird and it has these pistons in it, any idea what the size the reliefs are? Theres four. I cant find anything on google.

 

I used those pistons in my 350 with a 268xtreme cam, and I know alot of people use bigger cams than that. There are several things that can effect piston to valve clearence. What size cam does he have in it, and what size valves?

As far as the depth of the reliefs I don't know if there is a standard or not.

If you are running a large cam, it's always a good idea to check PTV clearence.


Jason

 

Can't help you on valve reliefs, but with the open chambered heads such as 882's and a .039" gasket, they yeild around 8.9:1 comression. Roughly 9.9 or so probably with 64cc and the same gasket.

Hope that helps a bit.

 

i havent looked at it myself yet, he's getting me the head numbers tonight, apparently ive been recruited to hot rod it and install it for him. My main concern is I know they have a different compression height that regular pistons and im trying to work out the compression before we decide what to do.

 

According to the Federal Mogul book the valve relief volume is 5cc's. the compression height is1.54"
usuallyn the piston is at least .045" down in the bore at TDC. sometimes further. .055" is not unusual.
you will need to install the pistons in your block to see your deck clearance.
Most other pistons have a 1.56" compression height.
If you want decent compression and quench, plan on decking the block. Other than that they are good pistons.

 

thank you!