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Old 03-06-2007, 02:48 PM   #1
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Default 4.3 lower end

Has anyone ever atempted to install 3.8 upper end on the lower end of a 4.3? i was thinking with a set of custom pushrods, it would work and work well. tuning aside. i think it would be a very nice build for na.

is the bolt pattern different? if so could i have a machine shop build a custom adapter plate?

would this even work or is it a pipe dream?
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Old 03-06-2007, 03:31 PM   #2
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4.3 is a 90* V6, as it is a 350 with 2 cylinders lopped off. Also the block is larger than the 3800 block, so you have no chance of anything working on it.
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Old 03-06-2007, 03:37 PM   #3
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i think the 4.3 is a 60 degree V6 and the 3.8 is a 90 degree V6
i could be wrong
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Old 03-06-2007, 03:38 PM   #4
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4.3 is a 90 degree
2.8, 3.1 and 3.4 are 60 degree
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Old 03-06-2007, 04:21 PM   #5
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there is a stroker Kit available for the 3.8. I forget the vendor
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Old 03-06-2007, 04:27 PM   #6
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The spacing between adjacent cylinders would be wrong.
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Old 03-06-2007, 08:29 PM   #7
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Quote:
Originally Posted by J Wikoff
The spacing between adjacent cylinders would be wrong.
Not to mention the cylinder head bolt pattern as well...talk about a square peg in a round hole solution!

Seriously, you can't put heads from one family of motors onto the block from another. It just don't work.

If you dig around, there'* probably better than stock Vortec heads out there. I think I recall a GM Performance aluminum Vortec V6 head available for sale. There are probably others.
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Old 03-06-2007, 08:40 PM   #8
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Now lets get a turbocharged 4.3L Get building!! But would it mount to the tranny?
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Old 03-06-2007, 09:08 PM   #9
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I think you can get a GM Splayed head to fit.
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Old 03-07-2007, 01:49 AM   #10
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4.3'* are a 90* V6, based off of SBC ideas, but they're not in the SBC Family by any stretch of the imagination.

The 3800 (and the short run 3300) are in their own family.

The 60* v6 engines are the other V6'* in GM'* stable. 2.8> 3.1> multitude of 3.4s, 3100'* etc...

Vortec engine parts are designed to create "truck" power bands, very low end power, nothing up high, and can't rev for ****.
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