Compresion Pin Height of 2.8 & 3.4 pistons ?

[rvbilly]

Hi to all of ya > I`ve been searching and can`t find the compresion pin heights of pistons from 2.8 & 3.4 pistons , anyone know what they are or have a source , Does GM actually offer a .120 oversize pistons for the 2.8 or 3.1 blocks ? How much can the iron head 3.4 ( from 93-95 Camaro ) be safely bored ? Been playing with the compresion ratio calculator and thought about boreing out a 3.4 alot and running about 10.5 to 1 compresion , I am going to use the Comp Cam 260-260 .440 - .440 lift cam , will there be any valve clearance problems if I shave the heads about .025 thousands , just want to build a minor build for my 1988 S10 , any help will be greatly apreciated , thanks Bill...

[bszopi]

http://60degreev6.com/showthread.php?t=27898&highlight=DISHES

Lists compression heights for various engines. Since this seems to be a popular question lately, I probably need to create an article for it so I don't have to keep trying to find the post over and over....

[ignoreance]

I think I may have asked the same thing and people keep getting it mixed up with compression ratio.....

First the two pistons 2.8 and 3.1 are the same diam 89mm 3.504 the 3.4L is 92mm or 3.622 so sorta yes .120 over if you want to get tech but. its not said that you can use these pistons per GM spec

The .025 on the heads can be done but your going to have to take off the intake manifold as well.. biggest gain take the manifold you have needs to be opened at the TBI Bore.... and the center is solid so don't be affraid to grind you can make an opening between both banks need to open to a mim 1.68 TBI bore bigger the better and then gasket to match....

Valve clearance isn't usally an issue tell you get in the mid .500's your taking .025 pluse your .440 so your clear for another .040 or so before you would really need to address that.

I need to and maybe as well as this guy here can't locate piston details that tell us how far the wrist pin is located in the piston. Top of side skirt.... to location of hole.... This information is what usally give us our piston to deck clearence when the stroke comes up. The stroke is 8mm longer on the 3.1/3.4 crankshaft so it would stand to reason that they moved the pin location up from where it is at in the 2.8L piston thus keeping the piston inside the block and not poping out. now GM may not have moved the pin location because they gave the 3.1/3.4 different CC dishes.... So if you have a 2.8L its a flat top piston and the 3.1/3.4 are dish but and yes on that page that you listed they are labled according to how much dish or -/+ CC volume but nowhere is the wrist pin location indicating that all pistons are the same... Get what the boys are asking now thats why the question has been asked over and over.... my mathmatics says its between 3.556mm and 3.962 now automotive rounding cus they love to name things bigger thats they are a 4mm ofset into the piston now that informaton tells me that if i use a 2.8 it will be .140-160 inchs higher in the bore now were cooking based off that calulation i get a derived compression value of 11.7 on the low side (and thats cus i have done some chamber work to the heads i have..) and the piston protruding out of the deck .120 cus if we have the stock deck height taking from the 2.8L high output the listed piston deck height is .026 make sense why were all asking this ???


Something tells me I have answered my own question and hopfully his but we want concrete details not theory...


As far as the .120 over piston 3.4L GM no though as far as I know .... aftermarket maybe could use a 327 350 piston??? don't know as some have different pin heights haha same issue..

[bszopi]

I am not getting it mixed up with compression ratio.

http://www.musclemotorparts.com/comp_ht.htm

Therefore, in the thread I gave you, it listed the compression height of various pistons, which in turn is the distance from the top of the piston to the center of the pin.

[ignoreance]

Never heard it called that.... Added it to my lib of terms....

[SappySE107]

Bump, thread linked to is dead and I didn't see an article. I need to make sure the difference in stroke is the difference in pin height for forged pistons to be made based off the 3100 specs I already have.