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Old 03-01-2011, 05:05 PM
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383 compression

i`ve got a 383 in a car hat i bought and the previous owner knew nothing of the internals. it was street driven an ran on 50/ 50 race pump gas. i`m gonna bracket race the car/pro street it. this year i`m gonna run whatever is in the motor. heres the deal... its got vortec heads on it and a solid cam (dont know if its a solid roller) compression test it and its at 225. whats the most liklely scenario? i`m thinking its the cam that happens to give real good low rpm cylinder filling (the cams not real wild if i had to guess adv. dur about 280 or so) it would be pretty unlikely for somebodey to put a domed piston in a vortec motor and i`m thinking a flat top in a 64 cc head with tight deck height could yeild around 11 to 1... anyways thoughts anybody

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Old 03-01-2011, 06:26 PM
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If you dont know,how are we suppose to know?

Pull a plug and shine a light with the piston up.
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Old 03-01-2011, 06:59 PM
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Based on the info you have given you have reached a fairly likely conclusion, you just need to do a little further checking. Yes, a flat top piston and 64cc heads puts you real close to 11-1 in a 383. Could be 10.8 to 11.2+ or so depending on how much block was decked, if heads have been milled, and thickness of head gasket used.
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Old 03-02-2011, 07:34 PM
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flattop with 64cc chamber, 0.042 gasket and 0.005 deck puts you at 10.82:1 , flattop (6cc), 64cc, 0.015 gasket, 0.020 deck puts you at 11.14:1
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