Problems with a 304 swap, 79 CJ7 -
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Unread 09-14-2009, 08:07 PM   #1
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1979 CJ7 
Join Date: Aug 2008
Location: USA
Posts: 33
Problems with a 304 swap, 79 CJ7

I just went back to add the pics, how do I do it?? There is no attachment button.

I bought a 1979 CJ7 258 with a bad rear main bearing with the intent of replacing it with a 304 from a 1982 CJ. I now have both motors and gear boxes out. The pics are attached. The problem is that the splined shafts and the clutch assemblies are completly different. Do I swap out the flywheels? From what I have been told this is an easy exchange. What about the motor mounts? They appear to be the same but do the 304 mounts line up with the 258 holes in the frame on the '79?

The blue 258 in the pics are the old engine from the '79 that I am trying to fit the 304 in. I want to use the gear box and transfercase from the 258 with the 304, its newer and has been recently rebuilt. The U joints appear to be different though.

Any help will be greatly appreciated.

Last edited by red240z; 09-15-2009 at 10:40 AM..
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Unread 09-15-2009, 09:39 AM   #2
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Join Date: Aug 2002
Location: Colorado
Posts: 14,874
You didn't attach any pictures, but the splines on the transmission input shaft only engage the clutch. They don't have a thing to do with the engine or flywheel. You may need to change the pilot bushing in the end of the crankshaft, but that would be all that you'd need to change.

Use the clutch plate and pilot bushing that goes with the transmission you're going to use.
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