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Old Mar 5, 2009 | 11:18 PM
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Boring a 390

Can any 390 be bored 80 over to be made a 428 with no problem.
 
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Old Mar 5, 2009 | 11:29 PM
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Originally Posted by shephard199
Can any 390 be bored 80 over to be made a 428 with no problem.
The short answer is no. Have your block sonic tested to make sure how far you can bore your block safely.
 
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Old Mar 5, 2009 | 11:46 PM
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No. Even if your block didn't have core shift, had the right thickness etc, you risk ending up with really thin cylinders. If you must, as per previous post, get it sonic checked. Read first:

https://www.ford-trucks.com/forums/2...questions.html

Remember, to make a 390 into a 428, you need the bigger bore, and you need a longer stroke. So, do what Ford did. Just add the stroke. With the stock bore, it's the 410 from '66-7 Mecurys.

Best to have the thickest cylinder walls you can anyway.

If you want to go bigger, a stroker crank can be had to give you a 445:

www.ScatCrankshafts.com
 
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Old Mar 6, 2009 | 01:33 PM
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I did it many years ago, but the block was one of the 375 horse Hi-performance blocks. For stand block it is just not possible for most of them.
 
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Old Mar 6, 2009 | 02:05 PM
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alright ill probably have it sonic checked, my reason for this question was I was wanting to turn my true 428 into a stroker/roller motor and take all my brand new parts and put them in a 390 thats bored so I dont loose money in them and the 390/428 would be goin in a 78 bronco but now Ive been told its hard to put a 390 in a 78 bronco that a 460 would be easier and i have one of those also so i dont know. Decisions Decisions
 
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