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Old 08-06-2010, 03:53:35 PM   #1
Rajin
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How much can a 350 be safely bored?

On a local classified site, a guy is trying to sell a 4 bolt main, 350 for $100. Casting Number: 3970010. He says that it's currently 30 over, but needs to be honed to 40 over.

Would it be possible to use this block to build a forced induction motor if it was 40 over?
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Old 08-06-2010, 03:56:31 PM   #2
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60 is about it on a gm stock block.
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Old 08-06-2010, 04:16:03 PM   #3
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Well you won't hone it to .040 over and while most 350 blocks can be bored to .060, it's a good idea to have it checked first as core shift can cause thin spots.

If you're planning to go forced induction, certainly have it checked out.
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Old 08-06-2010, 04:51:16 PM   #4
badazz81z28
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I dont think I would buy a block already .030 over...I would keep looking. My block was .030 over and when I tore it down one of the cylinders was grooved badly...Would not clean up. If you do buy it, tear it town and get it looked at first. Get a Re-build guarantee...
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Old 08-06-2010, 05:08:52 PM   #5
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It depends on what you mean by FI.
If you mean hardcore, real power type combination, then you have no business using any stocker.
If you mean barely over stock, a hundred or 2 HP, then may be??

If he's a stand up guy and not trying to pull anything, he should let you pay to have it checked??



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Old 08-06-2010, 05:20:34 PM   #6
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I was thinking twin turbo, 10 - 15 PSI. Nothing incredibly hardcore. The car will be street driven regularly.

I'm thinking 300 - 400 hp at the rear wheels.
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Old 08-06-2010, 05:29:55 PM   #7
z28rod
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Quote:
Would it be possible to use this block to build a forced induction motor if it was 40 over?
should be fine.
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Old 08-06-2010, 05:41:21 PM   #8
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The 350 (#3970010) that came in my car was .040" over. I planned on having it bored .060" over which my machinist said was fine as long as it sonic tested out ok. We never made it that far. I dropped the block off and he noticed right away when he started cleaning it that there were two cracks that some @$$ hat, more then likely the guy I bought the car from tried hiding with epoxy.

He had another 350 (#3970010) block that was already .030" over when he got it and just needed to be cleaned up a tad. So he sonic tested it and bored/plate honed it to .040" over (said we could have gone .060" over if we wanted too) and I was completely fine with it. Mainly because the block was coming from him and everything checked out fine or he wouldn't have thought about using it if it didn't. I wouldn't buy or at least spend to much money on block that was already bored. Unless of course I was guarantied my money back if the block did pass a sonic test. Or if it was from a reputable machine shop, I'd still take it to my guy and have it checked though.
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Old 08-06-2010, 06:16:19 PM   #9
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IMHO, I'd pass on it ESPECIALLY since you want to put "forced induction" (blower?) on it. IMHO, the MORE block you have (standard bore to maybe .030" over) the better.
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Old 08-06-2010, 06:42:39 PM   #10
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Can you even keep a twin turbo to 3-400 HP and why spend all that dough for such a low powered combination???


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Old 08-06-2010, 09:47:49 PM   #11
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If it makes more than 3-400 hp, awesome. Right now, I only put down around 200, so 3-400 is a pretty good improvement.

As for reasoning, I find that superchargers are quite a bit more common on muscle cars than turbochargers. Combined with the fact that I want something unique, and turbochargers have fascinated me for some time.
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Old 08-06-2010, 10:25:44 PM   #12
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you can easily go to .060 just make sure you half fill the block with ceramic block filler to stiffen up the cyl area around the water jackets
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Old 08-06-2010, 10:28:13 PM   #13
z28rod
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you can easily go to .060 just make sure you half fill the block with ceramic block filler to stiffen up the cyl area around the water jackets
what if it is a street car ?
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Old 08-06-2010, 10:34:04 PM   #14
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Quote:
Originally Posted by z28rod
what if it is a street car ?


i've run sbc's with block filler at the bottom of the side freeze plugs on the street with no issues
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Old 08-07-2010, 09:52:50 AM   #15
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Quote:
Originally Posted by Rajin
If it makes more than 3-400 hp, awesome. Right now, I only put down around 200, so 3-400 is a pretty good improvement.

As for reasoning, I find that superchargers are quite a bit more common on muscle cars than turbochargers. Combined with the fact that I want something unique, and turbochargers have fascinated me for some time.

I think the depth of your wallet will be the uniquie factor of twin turbo's on the street...
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