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Old 03-31-2013, 12:34 PM
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4.2l head

I'm planning on replacing my head on my 4.2l I've read about putting on 4.0 head and I was just wondering what the advantage would be of doing that instead of a 4.2 head
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Old 03-31-2013, 01:24 PM   #2
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the advantage is the 4.0 head flows better, to get the most out of it you really should switch to fuel injection and a fi cam. the 4.2 head can be improved upon by cleaning up the casting inside the exhaust and intake ports and port matching the intake manifold to the head. there are some vids on utube that show how.

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Old 03-31-2013, 07:43 PM   #3
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They raised the ports in the HO head, consequently you need to use a header/exhaust manifold from a 4.0 as well.

The later years of the 4.0 intake is animprovement too....but you'd need to get an adapter or fab a spacer & redrill it to use a carb.

The advantage is about 40HP if you update everything.
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