355 lt1 machining questions
06-11-2008, 09:24 PM
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355 lt1 machining questions guys who rebuilt their motors... how much did you guys deck the block and such? sending into the machine shop next week and i have to do some measuring to see how far i want to deck. at zero deck, are you guys having intake sealing issues, or machining the intake too? its a forged .030 over shortblock getting built.
06-11-2008, 09:44 PM
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If your machinist is sharp he can make some measurements and set the deck where you want it without mocking it up first. If he doen't build a lot of real world serious race engines, then probably not.
Zero deck? Depends on which gaskets you are going to use. If this is a street engine I personally would not want the total deck (including the gasket) tighter than .038". I have built many race engines closer than that but wouldn't put a street engine together closer. Factory specs come out .062" total. No need for that much, it will be quicker and less detonation prone if you tighten that up to .038" or .040". The factory F body gasket is .047" compressed thickness. I prefer Fel Pro .038" or the GM "B" boy gasket which is .029", and the pistons .008" or .010" in the hole.
Don't use plain old sbc replacement pistons and rings. It will be slower than a factory short block. You may have noticed the narrow, low tension rings the LT1 came with. You don't want to go backwards. I can't count the "built" LT1s I have dyno tuned that made less power than a factory short block would make. Ater talking to them I find out the machine shop sold them an inexpensive regular sbc rebuild kit. Wide, stiff, heavy rings. Way more rotatig frictional losses than how they came from the factory.
Good luck, Ed
Zero deck? Depends on which gaskets you are going to use. If this is a street engine I personally would not want the total deck (including the gasket) tighter than .038". I have built many race engines closer than that but wouldn't put a street engine together closer. Factory specs come out .062" total. No need for that much, it will be quicker and less detonation prone if you tighten that up to .038" or .040". The factory F body gasket is .047" compressed thickness. I prefer Fel Pro .038" or the GM "B" boy gasket which is .029", and the pistons .008" or .010" in the hole.
Don't use plain old sbc replacement pistons and rings. It will be slower than a factory short block. You may have noticed the narrow, low tension rings the LT1 came with. You don't want to go backwards. I can't count the "built" LT1s I have dyno tuned that made less power than a factory short block would make. Ater talking to them I find out the machine shop sold them an inexpensive regular sbc rebuild kit. Wide, stiff, heavy rings. Way more rotatig frictional losses than how they came from the factory.
Good luck, Ed
06-12-2008, 07:38 AM
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Eds right, select your piston carefully and make sure that it uses a the smaller ring. If youre just doing a .030 overbore then you'll have plenty of options, but stay away from the big rings. Also the zero gap rings are worth a few ponies.