455 main capa

Old June 16th, 2018, 06:36 PM
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455 main caps

I seem to be in a pickle lol. Iím a novice at this so I need a little help. Long story short, I need main caps for a 455 block that I picked up.

Since I donít have them, how much of a pain in the *** will it be to remedy this? Is it better/cheaper to find another block? Or is it cheap enough to just find some caps and have them put on?

I guess the machine shop will have to drill new holes for new cap screws? Whatís the process?

Thanks for for the help.

Last edited by Rosco920; June 16th, 2018 at 07:38 PM.
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Old June 16th, 2018, 07:30 PM
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It will probably be less expensive to find another block. The caps are machined to match the block at the factory and finding another set that is even close is just about impossible. You could buy aftermarket caps and have them installed but unless you are really planning to make a lot of power that is probably not economically feasible.
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Old June 16th, 2018, 07:31 PM
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New caps from another block will fit directly except that the block and caps will have to be line-bored or honed so the holes will be perfectly lined up and round.
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Old June 16th, 2018, 07:34 PM
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Originally Posted by Run to Rund View Post
New caps from another block will fit directly except that the block and caps will have to be line-bored or honed so the holes will be perfectly lined up and round.
so I should be about find some main caps from another 455 and it should work? I seen the mains on eBay for $45 except heís missing 2 bolts. Is it worth getting?
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Old June 16th, 2018, 07:40 PM
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Originally Posted by Run to Rund View Post
New caps from another block will fit directly except that the block and caps will have to be line-bored or honed so the holes will be perfectly lined up and round.

Have you actually done that yourself ? If you had you would know how difficult it is to find a set of caps from one block that will fit on another one without being a major pain in the *** . The problem is that they very very rarely line up side to side and there is really nothing you can do to correct it properly. Also getting the thrust to match is almost impossible.



He will definitely be better off finding another block. They are not that rare, at least not around here.
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Old June 16th, 2018, 07:41 PM
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Rosco, Ask your machine shop what he thinks about it
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Old June 16th, 2018, 07:52 PM
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Looks like Iíll be buying another fn block. Iíll look around for another one. Iíll try to see the one I got
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Old June 17th, 2018, 07:08 AM
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Originally Posted by BillK View Post
Have you actually done that yourself ? If you had you would know how difficult it is to find a set of caps from one block that will fit on another one without being a major pain in the *** . The problem is that they very very rarely line up side to side and there is really nothing you can do to correct it properly. Also getting the thrust to match is almost impossible.

Yes. It is not the big deal you make it out to be. The caps from one block will bolt to another. Obviously you MUST have the block and new caps line bored fo fix any alignment problems. The factory machining tolerances are nowhere near as loose as you are implying. Frankly, a line bore is cheap insurance during a build anyway.
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Old June 17th, 2018, 10:04 AM
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Originally Posted by joe_padavano View Post
yes. It is not the big deal you make it out to be. The caps from one block will bolt to another. Obviously you must have the block and new caps line bored fo fix any alignment problems. The factory machining tolerances are nowhere near as loose as you are implying. Frankly, a line bore is cheap insurance during a build anyway.
x2
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Old June 17th, 2018, 06:20 PM
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Joe,
I have not done that many Olds engines but on Small and Big Block Chevy's and most other engines I have seen the difference from block to block is so bad that it makes it almost impossible to match caps from one block to another. The thrust is really hard to match. Obviously the vertical measurement is not an issue because you are going to grind the caps down some anyway but on the Chevy engines the side to side register is so terrible that it is very hard to get a nice clean round main bearing bore.



Maybe Olds did a better job of machine work than the rest of GM
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