304 swap???'s

304 swap???'s

vintagetrks

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Paulden,Az
Vehicle(s)
1980 CJ7 258 I6 T176 D300 dana 30 Frnt Amc 20 rear
4in Rough Country Lift
31in tires soon to be 33's
I just bought an 80 CJ7 with the AMC 258 i6 / 4.2l and a 4 speed it has a Dana 30 up front and an AMC20 in the rear and a Dana 300 transfer case. I'm somewhat familiar with some of this set up having had a couple fsj's. But most of my knowledge is based on the TJ. Having said all of that I have been thinking of swaping a AMC 304 into my new mistress LOL. Is a AMC 304 swap fairly easy? I'm thinking that it should be and I should be able to just bolt it up and put an exhaust on it and go. Am I wrong? Will I need to change motor mounts? Will the wiring be an issue? Any advice or suggestions would be very appreciated. Thank You all. :D
 
Fuel line will have to be re-routed. I took mine up to front and then across and back to V8 fuel pump. I would recommend Bomb-proof one piece motor mounts. They bolt directly to frame and have round bushing on block side and are way better than the stock ones. A few wires like water temp and oil pressure will need extending to reach V8 positions. I used an HEI distributor from Summit and made that piece easy. I also used an aluminum cross-flow radiator from 4WD hardware and have no cooling issues.
 
Find out what 4 speed you have. The only one from 1980 that can handle a V8 would be the T-176
 
Find out what 4 speed you have. The only one from 1980 that can handle a V8 would be the T-176
I've been trying to figure out which 4 speed I have but have'nt been able to find any identafying marks. Its matted to a Dana 300 tc.
 
It may be easier to find an AMC 360 over the AMC 304 ; more power and the cost to rebuild is a little cheaper than the AMC 304 in most cases.

I'm starting to find out that the 360 was a much more commonly used powerplant for sure. The main reason I wanted to go with the AMC 304 was eaas of installation. I was thinking it would need the least amount of mods to get it in the jeep and going. But now that you mention it a 360 may be the best way to go.
 
I thought the AMC 304 and the 360 went in the same. I only went with the AMC 304 because it was cheaper then most 360's in my area and there is a lot of 360's out there. I understand that could be good if I ever needed something and had a 360 but I'm finding out that the AMC 304 's and 360's use many of the same parts...
 
I thought the AMC 304 and the 360 went in the same. I only went with the AMC 304 because it was cheaper then most 360's in my area and there is a lot of 360's out there. I understand that could be good if I ever needed something and had a 360 but I'm finding out that the AMC 304 's and 360's use many of the same parts...


from what i've read the AMC 304 , 360, and 401 are all the same external dimensions.
 
from what i've read the AMC 304 , 360, and 401 are all the same external dimensions.

They are. It's like the Chevy small block. From the outside, they are all mostly the same. The insides don't match but you can take everything off the outside of a 305 and bolt it to a 327 or a 350. Well, at least the front accessories and the motor mounts.

The biggest external difference on the AMC is the flywheel/flex plate. They are balanced differently. Taking a 401 flywheel off and running it on a 360 will cause the 360 to vibrate, causing premature failure of bearings and so forth.
 
Well the guy I'm getting the AMC 304 from said he took the flywheel off of it and put it on the 401... :wtf:
 
Well the guy I'm getting the AMC 304 from said he took the flywheel off of it and put it on the 401... :wtf:

Think he's gonna have issues with that flywheel. IIRC when I was into FSJ's several folks on the IFSJA often spoke of engine swaps and the need to have the correct flywheel as the cranks are different therefore the flywheels are weighted to each engines crank characteristics.
I;m also going to be swaping a AMC 304 into my rig so I'm hoping to learn from your build if your going to post your progress I'm sure it would be greatly appreciated.
:grinjeep:
 
Why would you pull the AMC 258 i6 / 4.2l ?????????? it is a great engine. You can do the 4.0 head swap, the team rush ignition upgrade and put the Howell fuel injection on that puppy and it will have all the power of the AMC 304 without all the expense. In addition you won't have to swap out the transmission. You'll be in it for less cash and have better gas milage and the same amount of power. Trust me I know! I have an 84 with a AMC 258 i6 / 4.2l and an 1986 with a AMC 304 . The AMC 304 can pass anything on the highway .........except a gas station. Honest think about it. Heck if you make me the right price I'll sell you my 1986 with the AMC 304 and you'll be money ahead and I'll be free of a headache!
 
What kind of gas mileage are you getting with the AMC 304 ? I mean not to be to bluntly rude but I hear a few complaining about the mpg of the V8's and no numbers. If they are under 12 mpg then that is something to seriously consider. But if it's better then that I don't see an issue. Many jeeps like mine are getting around 14 mpg now with the 4 banger.

Honesty I never wanted to go the V8 route. I was looking for a 4 banger diesel but they are just way out of my price range. I had a AMC 258 i6 / 4.2l but was talked out of that for a 4.0 EFI. I ended up installing that in my 88 woody waggy that had a blown block. I just never looked for another until I came across a AMC 304 that I bid on by impulse. I won the bid and well you know the rest. I pick up the motor this weekend. I'm just looking for more power then the 4 banger that will turn my 35's easier with out breaking the bank, to much mods, and won't decrease my mpg to bad then what I'm getting now.

That is why most folks go with V8's. I also think some just thing bigger is better. I however do not. I think planning is better.

The point of my post is we need numbers...
 
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What kind of gas mileage are you getting with the AMC 304 ? I mean not to be to bluntly rude but I hear a few complaining about the mpg of the V8's and no numbers. If they are under 12 mpg then that is something to seriously consider. But if it's better then that I don't see an issue. Many jeeps like mine are getting around 14 mpg now with the 4 banger.

Honesty I never wanted to go the V8 route. I was looking for a 4 banger diesel but they are just way out of my price range. I had a AMC 258 i6 / 4.2l but was talked out of that for a 4.0 EFI. I ended up installing that in my 88 woody waggy that had a blown block. I just never looked for another until I came across a AMC 304 that I bid on by impulse. I won the bid and well you know the rest. I pick up the motor this weekend. I'm just looking for more power then the 4 banger that will turn my 35's easier with out breaking the bank, to much mods, and won't decrease my mpg to bad then what I'm getting now.

That is why most folks go with V8's. I also think some just thing bigger is better. I however do not. I think planning is better.

The point of my post is we need numbers...
x2. i also have the 4 banger and want more power to turn 35's. but i figure if i'm going to upgrade i might as well do it big. i was planning on going for a 360
 
reptile, I would think about it seriously on what motor you truly want to go with. Don't do a V8 just because you think it would be better because it's bigger. I truly don't believe that. I mean, like I stated I did an impulse buy on that AMC 304 and I'm a man of my word so I'm taking it. I've been doing some thinking on my own and may just end up selling it or try to trade for a good running AMC 258 i6 / 4.2l .

I've been doing research on the AMC 258 i6 / 4.2l and there are some pretty good external upgrades that can be done to a stock AMC 258 i6 / 4.2l that will yeild close to or more power then a AMC 304 /360! The cost would be around 1200 bucks or so and can be done in stages to save up for the upgrades and keep the motor running while doing it.

I had a very reputable machine shop tell me that they could take my AMC 150 and turn it into a torque monster that would out perform a AMC 258 i6 / 4.2l ! I loved that idea. Only problem is cost. It would run me about 4800 to do it. Hell I can get a great running diesel for that much.

That is why folks do what they do. Money. I got the AMC 304 for 300 bucks. I think that was a decent deal going by other ads in my area for AMC 304 's and 360's. Yes the motor needs external parts but look @ it like this. I will be installing new parts so I know if the motor runs I should be 75% good to go.

But you have to factor in other cost when doing a motor upgrade or swap.

Weight of the new motor
MPG of the new motor
Other mods needed to make the new motor work
then do you have the funs to keep it running

I'm sure everyone on here has thought about all this through and true...
 
Well this is a discussion with a lot of right answers...just depends on your angle.

I have a AMC 304 and I'm fine with it, but I didn't buy the Jeep because it had one nor would I have not bought one with the AMC 258 i6 / 4.2l . Either is fine and stock there's very little difference. I would say it's alot easier to work on some things with a AMC 258 i6 / 4.2l because you simply have more space.

You want economy? Add power and keep your foot out of it. Happens every time. My buddy has an 08 Ford Diesel 3/4 ton all chipped up and he gets just over 700hp at the rear wheel...he also gets 28mpg on the Interstate driving it normally / responsibly. He can also get 12mpg by acting like a teenager on the same stretch of road.

You can build up a AMC 304 /360/401 or a AMC 258 i6 / 4.2l / 4.0 and get decent mileage, but you won't by chirping tires - you will by having an engine that breathes and doesn't have gas dumped to it by the driver.
 

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