new motor build 75 307 chevy 307 HELP
#12
08-05-2011 | 07:35 PM
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Joined: Nov 2008
Posts: 2,614
From: under the hood
My thoughts there exactly dj. I wasn't aware there was that much extra material in a 307. Most blocks have plenty for an .030 overbore, more than that and you want the block to be closely checked out first. But this one is way more than that even. The 307 block casting wasn't used for a 4" bore engine, so that too should tell you something. I've had a 307 in a previous Camaro, and rebuilt it using 327 heads, so there's no issue with using different heads. It's still a small block, just a little smaller (inside). I'd also be concerned about that engine running too hot (since there's so much less material between the cylinder walls and water jackets), so keep a good eye on the temp. gauge.
I didn't think a 307 could be bored THAT MUCH. You disappoint me 69. Get out the slide rule and figure out how much it must be bored to get that displacement.
.030 gets you about 5 cubic inches. He would need 9 times that so, .030 x 9= carry the 1, subtract by 3, spin around twice. hmmmm, that's around 1/4 inch
#13
08-05-2011 | 09:32 PM
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From: The 'Burbs of Chicago
I didn't think a 307 could be bored THAT MUCH. You disappoint me 69. Get out the slide rule and figure out how much it must be bored to get that displacement.
.030 gets you about 5 cubic inches. He would need 9 times that so, .030 x 9= carry the 1, subtract by 3, spin around twice. hmmmm, that's around 1/4 inch
.030 gets you about 5 cubic inches. He would need 9 times that so, .030 x 9= carry the 1, subtract by 3, spin around twice. hmmmm, that's around 1/4 inch
#14
08-06-2011 | 03:51 PM
4th Gear Member
Joined: Nov 2008
Posts: 2,614
From: under the hood
nope. I was messin with ya. I didn't think a 307 could be bored that much. I'm not good at all that math but fortunately, he's talkiing 43 cid increase or approximately 5 times an 030 bore so I could cipher that
that's a LOT of boring
#15
08-07-2011 | 12:20 PM
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Joined: Feb 2009
Posts: 819
From: Arizona
well the bore of the 307 is 3.875....so to go to 4 inches, its .125". That is a lot of material to remove to get you to a 350? nope, you'll get around a 327 with that, only after the 350 crank is stuffed in there do you get your 350. I doubt the 75 block has thick enough walls to handle that type of machine work. However, if that is the case then he'll just have to be very very carefull on his temp.
#16
05-13-2012 | 02:35 AM
you did what??? i dont think the cyl walls on a 283/307 have enough thickness to safely bore it to 4in. sounds like a expensive grenade to me
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