258 swap for 304

jambo82

New member
I am currently rebuiling my 82 Jamboree and would like to replace the original 258 with a 304. Will the 304 bolt up or will I have to install a conversion kit. Please advise!
 

Yes it will bolt up. Fitment is from 80-86, 6 or 8 cyl.
 
Actually the bell housing to motor pattern is the same starting in 1972 and should go until the end of the TJ in 2006. I have never seen an AMC V8 in a TJ but in theory it should bolt up to the bell housing. (Please, someone tell me if I am wrong.) The passenger side motor mount will need to be relocated to go from a 258 to a 304 but this is not a hard job. Also you will need to make sure you have the proper flywheel for the 304 as the AMC V8s are externally balanced with the flywheel and each size motor has a different balance. The 304s typically came in a CJ with a manual transmission behind them so you should be OK but some didn’t. The clutch system will all be the same as your 258 and the transmission and xcase both stay put so no driveline work.
 
I was going to do that myself in my CJ5 and I know it would be cheaper for me to do that, but.... I am going to build up my 258. Well actually, it is a 232 right now. I am going to put a 258 crank in it, put on a 4.0 head and with some stuff from Cliffords, have a hot 258 that will supposedly out perform the 304. Actually the 304 does not have that much more HP than the 258. But good luck with the 304 it is what ever you want. DON'T forget, the AMC 360 and 401 will also bolt up just the same.
 

Go with the 360 if you haven't already obtained the 304, get the 401 if you want crazy gobs of power.
 
I am going to build up my 258. Well actually, it is a 232 right now. I am going to put a 258 crank in it, put on a 4.0 head and with some stuff from Cliffords, have a hot 258 that will supposedly out perform the 304.

There's nothing like a bellowing straight 6. Way to keep it classy.
 
There's nothing like a bellowing straight 6. Way to keep it classy.


For raw, low end torque the AMC I6 can not be beat. It was a crime for Daimler to kill it; pure Yankee ingenuity at it’s best! (Like the Germans have a better idea of how to power the vehicle largely responsible for their defeat in WWII. Hum, as I recall weren’t the Italians on the wrong side of that equation too. Hum….)
 
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There's nothing like a bellowing straight 6. Way to keep it classy.

Yep, I wanted something different. And.. it is so nice to look down in the engine compartment and have so much room. And finally, it is going to be nice seeing the looks on peoples faces when they see that it is a 6 cylinder.:shock:
 
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