79 258 to 4.0 cylinder head conversion

Hello,

has anyone ever done the cylinder head conversion from a 258 to the

4.0 HO cylinderhead (using the clearwater head ?)

I have a '79 CJ5 and want to replace the cylinder head, intake manifold and use a header instead of an exhaust manifold (been thinking about getting a clifford intake manifold and exhaust header) I have that exhaust leak that I never could get fixed and now the exhaust manifold has a crack I figured I might as well replace it all.

Any tips pointers ? better ideas ?

thanks,

Ron

Reply to
csdude
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Hmmm... nobody has done this conversion ?

Reply to
csdude

I've read of it, but nobody I know has done this. There are a few writeups for putting an HO head on the earlier I6, but that requires blocking water passages and some millwork. Sounds like a cool project though.

Reply to
DougW

eups for putting an HO head on the earlier I6, but that

project though.

I saw a few write ups too. I asked around and it is not impossible. (some have even done it).

The block and the head do match, 'bolt hole wise' my block even uses the 1/2" headbolts. So that all works. I can get the head via a machine shop that re- manufactures heads and they flux weld the extra water jacks in the head that the 258 doesn't have. (They do it the right way by 'baking' the head, weld when hot, bake it again to get the stress out and than machine it.)

The whole purpose of the operation/swap is to get some extra horses out of it. The 4.0L HO head "breaths" better. So in order to not limit the performance of that new head one also has to figure out what intake manifold and exhaust header to use, exhaust itself might be worth looking at too and of course carburation. Does anyone have those 'numbers' ? or is following the original 4.0L setup a good idea ?

I talked a bit to a guy from Clifford. it seems that they have an intake manifold and an exhaust header that according to him works very well. (but of course they sell the stuff.. and usually you won't hear someone say "don't buy mine, it's no good for what you want"

Reply to
csdude

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