03-23-2020, 11:52 PM
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#17
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Registered User
Join Date: Oct 2015
Location: Ottawa, Ontario, Canada
Posts: 750
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Re: Small block 400's???
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DO NOT USE ANY STOCK 75-LATER CHEVY HEADS ON A 400. In 1975, Chevy started cutting corners on their heads to save a little weight. In 75 the heads had a second exhaust crossover port added which produced more head heat. And by the late 70s, all SB heads (except the Bowtie heads) were light weight, thin wall castings. ANY machinist who has lots of experience with SB heads will tell you that Mid-70s and later heads are either cracked when they come in, or, they probably will crack soon.
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I did know about the heads. But I was not using factor heads anyway but would that be due to the over heating as 400's did make more heat top end of the motor if you did not keep eye on it, or your cooling was not 110 %
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 1977 REG cab Long Bed with a 1984 Front Clip, 82 305 .60 over 9.0.1 flat top pistons, 4bbl, TH350, w/84 SS-intake & cam , w/ 1977 big block rad, 1975 gear box, 1984 master w/ metric fittings top & SAE fitting @ portion block, 1975 3.42 gear open diff. Duel 77-87 Factory air cleaner, duel inlet from rad support . Down sized 9' to new 8' Steel flat bed
Was a 77 454 w/308 gear. Taken out 550 lbs. up front with motor clip change.
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