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Discussion Starter #1
It is my impression that only the 96/97 3.8 MN12's had the option for headers. Just had a brainstorm. Are the heads from a 96/97 3.8 MN12 compatible to swap onto a 91 3.8? I was planning to get the stock manifolds ported and/or jet hot coated. If this swao is possible, it will be on the menu. Just wondering how the clearance will be. Any input...?
 

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Motorboatin' SOB, Headlight Cleaning Guru
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the heads are the same. 96/97 headers will work and fit. just swap the headers and you will be set. you will also need 96-97 drivers side downtube (or have a shop make a new one), the egr tube, and dipstick and dipstick tube off the same car.
 

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Moderator, Iowa Chapter Director, Uber Luber, TCCo
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Actually you don't really need the dipstick and dipstick tube. I did the swap and it works fine.

I actually do believe the heads are different though. The primary inlets on the shorty headers are circular and so are the gaskets. The manifolds are sort more rectangular and so are the gaskets. Having never seen 96-97 heads I can't really judge that though. This thought is based off of the manifolds/headers and their gaskets.

But you don't need to do a head swap. Just the headers, egr tube, and driver side downtube (or custom exhaust fabricated one). I only got the headers for my setup though. I chopped off and welded shut the EGR bung and then had my ENTIRE exhaust redone including the downtubes. Then I just capped off the EGR hole up at the engine top. It was 600 dollars for the whole setup, headers to exhaust tips.

-Thomas
 

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Discussion Starter #4
Good grief Thomas! is there anything you have not done :xpsmile: Thanks for the advice you guys. Just planning things out for next year. Considering another motor too, but I'll save that for another thread.
 

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Moderator, Iowa Chapter Director, Uber Luber, TCCo
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Wel I don't have a Vortech supercharger yet. :D
-Thomas
 

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Discussion Starter #6
Well, I suppose there is always something... Ill just use your sig as my shopping list:wiggle:
 

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ported manifolds will also do just fine for a stock to fairly well built 3.8 n/a... there is a lot of meat on the stock manifolds that can be ported out. i know someone who put in ported manifolds instead of the 96/97 shorties. i believe the opening on the manifolds was increased .8" maybe even almost 1". however, if you plan on adding a vortec or something in the future, maybe ported 96/97 shorties will be more worth it. -greg
 
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