engine bore
10-03-2008, 01:17 PM
#3
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347/331 have nothing to do with bore. That represents stroke. You can get within an inch or so with a stock bore. most however bore .030 over. i would not personally take a late model 302 more than .040. .030 is enough to get more HP out of the block than it can handle. if you have a late 60's model block you might get a little more maybe .060 or an after market block (FRPP or similar) most of those are made to accept as much as .125 over. find a good machine shop and listen to what they tell ya. you can learn alot there.
10-03-2008, 02:31 PM
#4
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As a rule, and just to be on the safe side, id never go over .030 on a stock block, period, even if its doable. I wouldnt bore an aftermarket block unless its new and/or you have the current bore written down somewhere along with the manufacturers max bore limitations.
Like said, 347 and 331 are stroke, not bore. The bore is the same on both they and the stock block. If anything youll have to notch the cylinders and pan rails for a 347 so the rods dont slam into them. Not sure about a 331.
.030 would give you a 306.
Like said, 347 and 331 are stroke, not bore. The bore is the same on both they and the stock block. If anything youll have to notch the cylinders and pan rails for a 347 so the rods dont slam into them. Not sure about a 331.
.030 would give you a 306.
10-03-2008, 04:51 PM
#5
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The overbore depends on the condition of the cylinders. The only reason for boring is to correct cylinders that are out of spec. You want to bore the least amount possible, leaving as much meat between the cylinder walls as possible. Most standard bores are .030, but I did have a 302 that had to be bored .040 to clean up the cylinders, and never had a problem with it.
10-04-2008, 03:15 AM
#6
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because the rebuild kits i were lookin at on summit was .30 and .60, i was thinkin 60's wayyyy to much on a stock block, i was thinkin .30 just wanted to get some imput beforehand. by the way its a 87HO motor
10-04-2008, 04:44 PM
#7
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A good machine shop will inspect the wall thickness, and tell you what bore is safe...
Due to core shift, that upper limit will be different for every block casting out there.
as already mentioned, the goal is to keep the bore as small as possible, but still get it cleaned up.
That way you can still rebuild the block in the future if need be....
Due to core shift, that upper limit will be different for every block casting out there.
as already mentioned, the goal is to keep the bore as small as possible, but still get it cleaned up.
That way you can still rebuild the block in the future if need be....
10-04-2008, 05:03 PM
#8
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