how big of bore gen 5 bbc

Old 03-18-2008, 07:24 PM
  #1  
randybryan
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Default how big of bore gen 5 bbc

I have a bbc marine, gen 5, 4 bolt block. Going to freshen. Thinking about a new rotating assembly. How big can you bore this block and still be reliable. It's a bracket/index motor. Dont want to fill block.
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Old 03-18-2008, 08:36 PM
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68bbnova
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454 or 502?
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Old 03-18-2008, 10:11 PM
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OneBadGMC
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If you're worried about reliability, don't go more than .060 over. Put a 4-1/4" crank in it and be done.
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Old 03-19-2008, 04:31 AM
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hink
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A soinic test would be the way to go!!!!!!
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Old 03-21-2008, 08:42 PM
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randybryan
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Default 454

it is a 454 block
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Old 03-21-2008, 11:48 PM
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cepx111
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Originally Posted by OneBadGMC
If you're worried about reliability, don't go more than .060 over. Put a 4-1/4" crank in it and be done.
DITTO!
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Old 04-04-2008, 11:03 AM
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TopspeedLowet
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Default Re: how big of bore gen 5 bbc

Originally Posted by randybryan
I have a bbc marine, gen 5, 4 bolt block. Going to freshen. Thinking about a new rotating assembly. How big can you bore this block and still be reliable. It's a bracket/index motor. Dont want to fill block.
I have been using a bow tie gen v block bored to 4.600 using 15 to one comp. and have no grout in the block. The GM max recomended bore for this block is 4.6". Grout is for bone stock blocks with core shift. A new aftermarket block is cheep insurance for block quality. You'll have more in machine work and gimicks to get the durability of a good block than a good block costs. You decide
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