boring a 455 - Pontiac GTO Forum
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post #1 of 9 (permalink) Old 01-21-2013, 09:37 PM Thread Starter
 
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boring a 455

I picked up a 455 that has already been bored .030 over. I would like to put it in my 1969 gto.

it will need to be bored again to be useable. I just want to know if the 455 will be ok at .060 over? will I have cooling problems? even after the water pump mod?

i did some research and am getting conflicting answers. I would like to know from someone who has done it maybe

Alex
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post #2 of 9 (permalink) Old 01-22-2013, 08:09 AM
 
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My 1970 455 has been bored. 060 and stroked to 474 ci. No cooling problems.
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post #3 of 9 (permalink) Old 01-22-2013, 08:45 AM Thread Starter
 
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That is good to hear. I've been reading that the later 455 blocks have thinner walls but mine is a 73.

I'm hoping to be able to go .040 over but worst case is .060 so I'm just wondering worst case. Any more input would be great.

It seems the only overheating issues are with the guys running without a shroud or some no brainier fix..
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post #4 of 9 (permalink) Old 01-22-2013, 02:40 PM
 
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You might want to have the block sonic checked just to make sure. It OUGHT to be good at .060, but you never know.
It is never a bad idea to bore as little as possible, so if going .040 would work I would chose that. Gives you some wiggle room later down the road.
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post #5 of 9 (permalink) Old 01-22-2013, 05:11 PM
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No sense throwing away what amounts to more life in your block.

Bear

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post #6 of 9 (permalink) Old 01-22-2013, 06:00 PM
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.060" will be the last time you can use the block, and it will need to be sonic checked. What these gents said is true. If you're getting custom pistons, see if it'll clean up at .035" and you'll have even more meat (and life) left.
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post #7 of 9 (permalink) Old 01-22-2013, 06:15 PM
 
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block

Heard a lot of talk about re-sleeving the cylinders. Would this be a viable option if it came down to it?
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post #8 of 9 (permalink) Old 01-22-2013, 07:51 PM Thread Starter
 
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I've done some more checking on the block and after cleaning it up it looks really good. I used a cylinder bore gauge on all the cylinders and everything looks good. i might even be able to just be honed at .030 over. if it came to it .035 with custom pistons sounds pretty good too.

I do have another problem you guys might have some good input on.

I have the 455 block and crank that I have been asking input on but it is the block and crank only. nothing else

I also have a 400 block that is .040 over and i should be able to get by with .045 over. but again it is bare block and I have nothing else.

I cant decide on the 455 with stock crank and edelbrock heads or the 400 with the stroker kit and edelbrock heads. the 400 stroker would be more money but would it be worth it? the only reason i say stroker is because I dont have a crank anyway. I plan to assemble this motor myself but have all the machining done by a shop.

any input or ideas would be great.
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post #9 of 9 (permalink) Old 01-23-2013, 11:21 AM
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Something to consider. The 400 with the smaller main journals means that there is more metal in the main webs on a 400 than there is in a 455 = a stronger block. (It does matter which specific 400 you have, some of the later models are actually weaker). If you're building for serious power, or think you might want to "some day", then a strong 400 is the better choice. They also oil better than the large journal engines (smaller journal = less rotational force working against the oiling system.)

When I was deciding on my engine build, I had two routes I could go. I had the original numbers-matching 400, and I had a 1970 4-bolt 455 block. I built my 400 as a 461 stroker, and I'm very happy with the results.

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