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BLS33 02-20-2007 06:22 PM

Official AMC V8 swap thread
People ask about swapping AMC V8's into their CJ's all the time, so hopefully we can use this thread to answer all the questions you may have. You can use this thread to ask more detailed questions about specific problems

-Passenger side frame mount needs to be replaced with one from a CJ that had the 304 (commonly found on ebay)
-Both side block brackets need to be replaced by ones meant for a CJ with the 304 (again check out ebay)
-Any local parts store will carry neoprene mounts you may need.
Thanks fuzz401 for the pics!
Frame mount AMC I-6 to V-8
I-6 3 slots / V-8 2 slots

CJ - V-8 block mount (bracket)
M.O.R.E. Makes a set of bombproof mounts which eliminates the need for any other frame mount, neoprene mount, or block bracket
because its all built in they can be found here:

AMC V8s are externally balanced, so use matching components for vibration dampers, flywheels, and flex plates. If your having trouble finding a 360 flywheel, a 258 flywheel can be rebalanced and used. You also need to keep in mind the correlation between the tranny the engine used to be bolted up to and the one in your CJ. For example if the engine was bolted up to a th400 but your Jeep has a tf999 you will need the proper flexplate (balanced to whichever engine you are using) to bolt up the the tf999's torque converter.

The only engine I'm 100% sure has a matching radiator outlet to AMC V8's is the 258. You can reuse the 258's radiator but
if you want to upgrade you can use a radiator meant for a CJ with the 304, if you are swapping out an I4 or 232 you should
go ahead and upgrade.

(this information is based on swapping out a 258, someone else can go deeper into the wiring of this and other engines)
Engines older then 1978 have the prestolite ignition system, while 78 and newer will have the duraspark system. The 2 arent
compatible with eachother, a way to solve this is go HEI. Other than that you may need to lengthen the coolant temp sensor

Use the wiring diagram for a 1980 CJ with a 304 V8, it will be correct for AMC V8 swaps.

I would just go custom on the exhaust. Hedman as well as some other companies (check make headers for this swap, otherwise you can just use the stock manifolds and custom exhaust from there. If the engine you are using is really old (66-69) you should make sure to get the stock manifolds because of the rectangular port heads.

This is probably the easiest of the V8 swaps, and with the help of JF anyone can do it! :thumbsup:

(If anyone sees any mistake let me know, also add anything you feel is needed)

plain76cj5 02-20-2007 07:08 PM

The fuel line for the six cylinder will be on the passenger's side and you will have to relocate to the driver's side for the AMC V8.

BLS33 02-20-2007 07:15 PM


Originally Posted by plain76cj5
The fuel line for the six cylinder will be on the passenger's side and you will have to relocate to the driver's side for the AMC V8.

Ah yes forgot about that. You can either switch frame rails or extend the line across the front to the other side.

jlutsey 02-20-2007 07:16 PM

will the flex plate and flywheel from a 304 work for a 360 swap?

BLS33 02-20-2007 07:25 PM


Originally Posted by jlutsey
will the flex plate and flywheel from a 304 work for a 360 swap?

They would need to be re-balanced to work with the 360.

luvdemCJ's 02-20-2007 08:20 PM

Thanks for this thread guys. I'm searching for a 360 right now. I'll keep a close eye on this thread for any additions and then print it off.

Thanks again!

Pick01 02-21-2007 02:02 AM

Your M.O.R.E. reference for mounts is for Chevy V-8's, not AMC. Just letting you know.


BLS33 02-21-2007 05:07 AM


Originally Posted by Pick01
Your M.O.R.E. reference for mounts is for Chevy V-8's, not AMC. Just letting you know.


Fixed it :thumbsup:

marmaduke 02-21-2007 05:32 AM

With mine I also had to swap the power steering hoses.
The clutch from my '86 258 fitted my '76 360 but the 'Y' pipe on the exhaust ran the wrong side of the transmission, the V8 was from a waggy not a cj so I went with the easiest option of fenderwell headers and side pipes.
When I used M.O.R.E. mounts I found the earth strap wasn't long enough.
I also swapped to a Holley 670 Truck Avenger and the accelerator cable wasn't long enough and didn't have the correct fitting on the end, so I ended up cutting it off and running a brake cable from a push bike through and that works a treat.

CJeep 02-21-2007 07:57 AM


Originally Posted by marmaduke
. . .that works a treat.

I wish there were more Brits who posted here. It really makes my day!

Gixxed 02-21-2007 08:05 AM

This should be a sticky thread just so it stays up top somewhere

nhcd538 02-21-2007 08:33 AM


Originally Posted by Gixxed
This should be a sticky thread just so it stays up top somewhere

X2. I've been planning this swap for months, looking here, there and everywhere for specific info. Having a "one stop shop" for all relevant information would have been nice. Someone needs to go in depth on power steering setups. Can I re-use my 258 pump and bolt it to the V8 bracket? Will the fittings need to be changed on the power steering lines?

I've also found some discussion on pilot bushings and which ones to use. The rule of thumb I've seen is use the pilot bushing that corresponds to your transmission, don't go by the motor. Is that correct?

Regarding bellhousings - it should be noted that any AMC V8 will bolt up where another AMC motor was. For example, an AMC 304, 360 or 401 will always bolt up to a bellhousing where a 258 was. Remember, there's more to it than that. You need to consider flywheels/flexplates (as mentioned above), pilot bushing replacement, and if you're swapping out a 4 cylinder there are bigger things to consider that I'm not exactly sure of.

Also maybe an in depth explanation of distributors, ignition systems...what works and what doesn't. This could be a great thread, lets get it going! :thumbsup:

plain76cj5 02-21-2007 08:42 AM

If you are going from 258 to AMC V8, you can use your same power steering pump on the V8 brackets. You will need a different pressure hose. The return hose is easy to lengthen or shorten.

The pilot bushing has to fit the crankshaft and the trans input. The 258 and the AMC V8's use the same size outside diameter pilot bushing. The inside diameter would depend on the transmission.

jgoshow 02-21-2007 09:31 AM

i have the 79 cj7 with the 304...what motor will drop in and connect to the trans? 360?302? i want to keep the v-8

Dropkick_pride 02-21-2007 09:50 AM

amc 258 and 304, 360, and 401 will all drop in and connect to your trans.

Great idea for a thread. I have been digging for info as well and to have everything in one place would be great.

I would love to hear some more about the exhaust routing and possible problems with manifolds/headers and different trannies.

The time now is 04:08 AM.

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