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Building a 283 to 302
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disco283
New User
| Posts: 1
| Joined: 04/09
Posted: 04/18/09
09:41 PM
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I have a 75 nova with a 67 283 engine. I have been told that i can bore and stroke it out to a 302, put in a 327 crank, and 350 pistons and it will all fit. Is this true?
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Posted: 04/19/09
01:34 PM
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You would have to bore it .125 over and I would not recomend boring any chevy engine that much.
Horsepower sells Engines and torque wins races.
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Posted: 04/19/09
02:45 PM
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283 with a 327 crank is a 307, SOME 283s can be bored .125 over to 4.00inches then it would be about 302ci, I don't think your 283 can be bored .125 over, thats only for real early 283s, like from the 50s.
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GibTG
Moderator
| Posts: 1904
| Joined: 10/03
Posted: 04/20/09
01:04 PM
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Some bore and stroke specs on order of increasing displacement...
The 283 has a 3.875" bore and a 3.0" stroke. A 302 has a 4.0" bore and a 3.0" stroke. A 327 has a 4.0" bore and a 3.25" stroke. A 350 has a 4.0" bore and a 3.48" stroke.
It is possible to bore your 283 to a 4.0" bore and then either have a 302, 327, or 350 depending on the crank stroke but this may not be such a good idea. You would need to have the bore thickness checked with an ultrasonic thickness gauge to determine if boring your block that far would be safe, and even this isn't a surefire bet as it's impossible to know the thickness at EVERY point in a bore's cross section. It's possible that the block's bores could become very thin with this amount of overboring and in a worst-case scenario the block could crack during use. The more power an engine makes, the more heat and pressure is created within the combustion chamber/cylinder and that needs to be contained to make power, this can cause bores to warp/crack if they're made too thin.
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Posted: 04/21/09
03:21 PM
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i never heard of a 283 being turned into a 302, but you can take a small journal 327 with a 283 crank and turn it into a 302
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GibTG
Moderator
| Posts: 1904
| Joined: 10/03
Posted: 04/21/09
03:35 PM
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A 327 crank in a 283 is a 307 - in fact GM produced those!
A 283 can be turned into a 302, just bore it .125". It's possible with some blocks.
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67ELCO302
New User
| Posts: 1
| Joined: 11/09
Posted: 11/07/09
08:14 PM
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If you can find a 327 that was a small journal crank block, you can use 283 .125 over bore pistons use the 283 crank and the 327 block and you have your 302. In the 70's it was the motor of choice. What you need, 327 small journal crank block, there is your 4 inch bore without any machine work, 283 pistons .125 over bore again 4 inch bore and your 283 crank. Really that is the way GM did it for the 69 Z-28's. I had one for a dirt track car, when I sold the motor guy put it in a pulpwood truck and ran it another 10 years.
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