Engine/Drivetrain question - JeepForum.com
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post #1 of 9 Old 04-06-2020, 11:34 AM Thread Starter
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1978 CJ7 
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Engine/Drivetrain question

Hello all, I have a '78 CJ7 with an AMC 304/TH400/Quadra-Trac. The combination only has 90,000 orig. miles and has been in the family since new, however, it has zero power with all the emission standards in CA. I came across a '84 AMC 360 and want to swap. I want to rebuild the TH400, Quadra-Trac, and 360 and use that combo. My question is will my hopes of using this combo work? (not sure if the '78 TH400 will mate with the '84 360)

Thanks all,

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post #2 of 9 Old 04-06-2020, 12:27 PM
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1974 CJ6 
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Yes, the 360 will bolt right up in place of the 304, just make sure that you get the correct flexplate. first off the one for the TH400 different from the TF727 that is likely behind the 84 360. also, you cannot use the flexplate that is currently on the 304 on the 360 as they are balanced differently. not a big thing though as you can get a new flexplate to put a 360 in front of your th400 as that was a factory option in the wagoneer/truck.

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post #3 of 9 Old 04-06-2020, 03:31 PM
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1978 CJ7 
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Is it legal in CA? The swap is easy, just dont want your next post to be that you have to sell it due to not passing CA emissions.
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post #4 of 9 Old 04-06-2020, 03:54 PM
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As long as it has all the smog from the newer engine should work out all and not hacked in.. But it is Cali and they can be PITA. best is have anything made 1975 down , exempted. 76 and up its must be 100% correct.

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post #5 of 9 Old 04-07-2020, 11:37 AM Thread Starter
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1978 CJ7 
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Good info Fourtrail, thanks!

It is legal in CA to do the swap. I'm going to put EFI on the 360 which will pass smog no prob and 222doc is correct, the smog emissions has to pass the year of the motor. I haven't decided on taking it to a referee though and have it registered a 360 or take my chances since the blocks are identical, minus the 360 stamp. I've never had a smog shop look at the block stamp to verify.

Anyone have an idea of how much horsepower the stock TH400 can handle? I want to do a couple extras to give a little extra umph….

Mild RV cam (haven't decided yet which one), Edelbrock performer heads, headers, and maybe something else. I would like 250-300 hp without modding the block. Just don't want to get the motor done then have to go back and do the trans. Not looking to drag. It is a summer DD with an occasional mild trail.

Thank You guys for your replies!

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post #6 of 9 Old 04-07-2020, 11:59 AM
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2004 WJ 
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Used to be California didn't like bigger motors swapped in. I can't see them changing their ideas about that.

However, nobody has to know it's a 360.

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post #7 of 9 Old 04-07-2020, 03:16 PM
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The stock TH400 can handle your 360 no problem.

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post #8 of 9 Old 04-19-2020, 11:09 PM Thread Starter
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1978 CJ7 
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Quick update, I have the transfer case out, the transmission is almost out, and the motor is coming out next. I am going to start purchasing parts for the engine rebuild. I am trying to follow all the number systems for cams and piston spacing but it is a bit much for me. If anyone has opinions on a good cam and an engine rebuild kit ('84 AMC 360) they are much appreciated. I am looking for something that is mild as I am not street racing but can give it some noticeable power. Just a recap of my intentions: Howell EFI, Edelbrock Performer Heads, Performer Intake, MSD ignition.

On a side note, I have taken down the motor to the crank and cam left. I can't take the crank out yet because the harmonic balancer does NOT want to come off. My puller can't get all three arms around it because the water pump and timing chain cover, etc, is still on because there is a bolt just behind the balancer that I can't get it. Any ideas on how to get that stubborn thing off?

Thanks all...

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post #9 of 9 Old 04-20-2020, 05:21 AM
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You gotta loosen the bolt. Use the bolt head for a place for the puller to push against.

Do NOT use a three armed puller on the balancer. There is a puller designed for this job that bolts to the HB.

Not looking to drag. It is a summer DD with an occasional mild trail.
You can build the engine, but just installing a stock 360 will be a nice bump in power. Go as far as you want, but an RV style cam and a small 4BBL will be more than adequate for most anything you will want to do. You can take all the money you saved on heads, EFI, headers, etc, and invest it in other things.

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