pistions specs.....
05-17-2008, 12:42 AM
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pistions specs.....
ok i builtthis engine...and am about to switch heads again this time to 180cc elimator heads 66cc well here my problem and some please answer this with what i hope...lol...ok block specs are forged crack standard 350.......eagel rods.....5.7 and here is the kicker.... " H345NP" .40 over pistions....... now..... i have esearced all night...some sites tell me there an extra .20 in the hole and otheres say the pin height is still 1.560 ......my block has not been decked any......so what ever stock is on a sb350 i think ".025" correct me if i am wrong the block was checked and its true it was milled slightly but not enought to change debth at all.... i am aming for 9-5-1 compression and well...if am .025 down the hole i will need .039-.040 thick head gaskets.....but that still amkes quecnh a little hight to.... but if the pistiopns are indeded i pray not an extra .020 down the hole that emans .045 total.... which is allready way to much quench.....and i am not gonna pull it back apart to redeck!.. bu that would mean i would need a .023 head gasket and quench would be .068!!! ouch! so someone please say there not .020 down the hole....
05-17-2008, 10:29 AM
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Car: 1988 Trans Am GTA
Engine: 350 4BBL
Transmission: 700R4
Axle/Gears: 3.27
Re: pistions specs.....
Why don't you just measure the actual deck height?
You need measure it anyway because it is one of the production tolerances that vary from block to block. Just because the wrist pin is in the stock location doesn't mean that you will automatically have a .025 deck height.
The oversize pistons usually have the stock piston pin location since they are going in a "new" hole. The ones that are .020 lower are usually the stock diameter rebuilder pistons that may be put in a "used" bore. They lower the piston so the new rings won't hit the ridge in the cylinder from the previous piston's rings.
All you need to measure the actual deck height is a straight edge and a feeler gage.
(y'all didn't think I could get my usual "measure, measure, measure" in didja
)
You need measure it anyway because it is one of the production tolerances that vary from block to block. Just because the wrist pin is in the stock location doesn't mean that you will automatically have a .025 deck height.
The oversize pistons usually have the stock piston pin location since they are going in a "new" hole. The ones that are .020 lower are usually the stock diameter rebuilder pistons that may be put in a "used" bore. They lower the piston so the new rings won't hit the ridge in the cylinder from the previous piston's rings.
All you need to measure the actual deck height is a straight edge and a feeler gage.
(y'all didn't think I could get my usual "measure, measure, measure" in didja
)
05-17-2008, 10:45 AM
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Re: pistions specs.....
Why don't you just measure the actual deck height?
You need measure it anyway because it is one of the production tolerances that vary from block to block. Just because the wrist pin is in the stock location doesn't mean that you will automatically have a .025 deck height.
The oversize pistons usually have the stock piston pin location since they are going in a "new" hole. The ones that are .020 lower are usually the stock diameter rebuilder pistons that may be put in a "used" bore. They lower the piston so the new rings won't hit the ridge in the cylinder from the previous piston's rings.
All you need to measure the actual deck height is a straight edge and a feeler gage.
(y'all didn't think I could get my usual "measure, measure, measure" in didja)
You need measure it anyway because it is one of the production tolerances that vary from block to block. Just because the wrist pin is in the stock location doesn't mean that you will automatically have a .025 deck height.
The oversize pistons usually have the stock piston pin location since they are going in a "new" hole. The ones that are .020 lower are usually the stock diameter rebuilder pistons that may be put in a "used" bore. They lower the piston so the new rings won't hit the ridge in the cylinder from the previous piston's rings.
All you need to measure the actual deck height is a straight edge and a feeler gage.
(y'all didn't think I could get my usual "measure, measure, measure" in didja
)thanks man i knoq i need to measure i am trying to amke this a 1day project.... and i am ordering a custom set of gaskets to meet what i need..so iw anted to have things ready...... but yes i will double check and measure measure measure.....thanks..... good to know it may very well be .025
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