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I am going to check out an engine and heads. 75 455 and 670 heads what should I keep an eye out for that might be warning signs as far as not rebuild worthy? I read that that is a light weight block and might have issues. True or False?
 

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a 455 with 670s wont runon pump gas unless it gets dished pistons in it.Just very hard to tell much without it being apart and having the heads and block magged and pressure tested.If apart just look for rust in the chambers and bores.Tom
 

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All 455 blocks are good to build on. I have a 71 4 bolt main(483677) and a 75 block (500813)the main webs look identical. They didn't go to thin webbs with roll pins for the caps on 455 like the 557 400 block
The earlier blocks are supposed to have some advantages Not sure what exactly maybe less core shift and better lifter bore support
 

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I had a 455 back in the 80's that I put 670 heads on and it was a disaster. It was a real bitch to turn over when it was hot, and I had to back the initial timing off so far, and slow down the advance rate that any hopes of having great performance went out the window. The only cool part was when I put Turbo Blue gas in it I could advance the timing and it actually ran damn strong, but Turbo Blue was like 3x $$ as 93 octane back then. Funny part was that when I ran straight Turbo Blue I could advance the timing as far as I wanted and it never did ping, so it was not a good fuel to tune with. It was just not practical to have that much compression. Only good thing was I did learn all about curving distributors, and not pulling in too much vacuum advance too quick.
 

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That 455 block is good, bu those heads going to bring your compression up too high. Good news is, there are tons of 6x heads out there you can get pretty cheap. They will work great on that motor.
 
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