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  #16 (permalink)  
Old 01-21-2008, 07:28 PM
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I am not sure if you measure your octane rating the same as we do. If you are on the same scale, I don't think you have a big problem with 12.1 to 1 compression ratio on 98 octane gasoline. A couple of questions: Do you add lead to your gasoline or is it unleaded like us? Can you get the casting number on your block to us so we can tell what you have? I suspect you have a 350 block. If the motor is mounted with a bracket attached to the front of the block, then it is probably an older block and it will not live long with a 4 inch bore. If it is mounted on the sides, there is a very good chance it is a 327/350 block. What heads do you have? The cheapest (and better performance) solution would be some good aluminum heads that definitely let you keep your piston set up and increase the size of the combustion chambers.

In the old days, the careful boring of the 283 blocks to 4 inches and using the 351 Ford pistons on specially machined rods produced a screaming 301. I just can not remember the specifics, but there were some after market pistons produced for this conversion (Jans stick in my mind but not sure)

Trees

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  #17 (permalink)  
Old 01-30-2008, 12:56 AM
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How to get a Chevy 302 under 10:1 CR

An update on where I got to

I found an SRP Piston with 10.4:1 with a solid dome which can be milled to flat top at http://www.flatlanderracing.com/srp-sbc302dome.html

The issue for me is the are 0.30 oversize and my block is 4".

My mechanic has a concern if a 283 block can be taken out to 4.030. He has a book that says it can but he is still concerned that given the age of the block that this might not be a great idea

I would appreciate any thoughts/opinion on this. Is he being over cautious?

Thanks a lot
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Old 01-30-2008, 05:41 AM
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You need to verify for sure if that is a 283 block and also what crank is in it.
If it is a 283 block there is another option: up untill 1968 the 283 and 327 shared the same main diameter on their crankshafts so you could sell off that little 283 cranks and install a small journal 327 crank. This will open up more options for piston selection and you'll enjoy the extra 25 more cubic inches. Finding a 63-67 327 crankshaft is not that difficult in fact most crank regrind providers will offer a crank kit with bearings for around $150. I wouldn't bore that block any farther if it is a 283 block. Depending on what heads you have you could get the compression you're after easily with flattop 327 pistons. If you have a factory 302 crank-sell it!
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Old 01-30-2008, 05:45 AM
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Yet another option: if that block is a small journal block you could also cut a 350 crank to small journal specs and buy 350 pistons. There's many 350 pistons to choose from.
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Old 01-30-2008, 06:44 AM
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Quote:
Originally Posted by baddbob
If you have a factory 302 crank-sell it!
Exactly, the proceeds from the sale of an original 302 crank could easily pay for the upgrade to a 327.

Vince
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Old 09-08-2010, 05:49 PM
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350/327/302

if you do (Google search for Chevy block cast numbers)you will find a lot of places that list a big part of Chevy block numbers. that how i found out i got a 302 for $450. lucky HaHa.
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Old 09-08-2010, 09:53 PM
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Last post was 2 1/2 years ago. He probably has it figured out by now.
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