390 to 428 stepup
Thread Starter
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New User
Joined: Oct 2003
Posts: 1
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390 to 428 stepup
Besides over boring the block and heads what else would I have
to do to step up a 390 block to a 428.
I've read in severl performance books this is possible, but they
always manage to forget to tell what is required to get the job
done.
to do to step up a 390 block to a 428.
I've read in severl performance books this is possible, but they
always manage to forget to tell what is required to get the job
done.
Post Fiend
Joined: Feb 2001
Posts: 6,624
Likes: 8
From: Missouri
All you need is a 410/428 crank and pistons. The rods are the same length. You must sonic check the block before deciding if it can take 428 bore (.080 over). I would leave it a 390 bore and make it a 410. The thicker the cylinder wall the better. You can use 1976 390 pistons to make a 410 as that is what they really are. For high performance applications you will have to either shave the tops of some TRW L2291 forged pistons or get some even better customs. Your best bet is to get a 73 or later mirror 105 block. They sometimes have thicker walls. They all have the extra main webbing just like the original CJ block.
