4.0 Head swap - which head to use???

4.0 Head swap - which head to use???

jeepindavis

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Location
Stevens, PA
Vehicle(s)
84 CJ7 Black,
84 CJ7 Brown,
98 XJ Chilli pepper red
I've got on the floor of my garage two 0630 heads from the 4.0 as well as two 4.2's that could use some better performance. I've been following threads about the 7120 and found The Dirty CJ's dyno results on his swap. Anybody swapped in an 0630? Results? Complications? I am curious if I should abandon these 0630's in favor of a 7120. If the better performance is from the 7120, I'll keep looking. However, considering that the 7120 would be from an older engine, I'm thinking that the 0630 might be the way to go. Any thoughts?
 
Use the 0630. They're just as good as the 7120 for performance. The only down side is if it's the later 0630 it may not have the hole behind the valve cover for the temp sensor. If not, you'll have to come up with another way to install the sensor.

Some web sites have said that none of the 0630 heads have the hole, but I know this is not true because I've seen a few of them that do have it.
 

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