304 with fuel injection worth it?

[GTOgoat]

Hello All,

I've searched some and cant seem to find a good answer to a question.

My goals.... Good daily driver that has the ability to go off road and do level 7 trails. And get that V8 side pipe sound!

I have a 1985 CJ7 that I want to put a v8 in and I know there are many forums on this and many on a AMC 258 i6 / 4.2l vs. AMC 304 . The Transmission I have (T-176 ) is not really strong enough for the 360/350 but will work with a AMC 304 . However, many say it's not worth the trouble to change from the i6 to AMC 304 . Also mentioned is don't bother with the AMC 304 go with the 360/350 which then circles me back to the Transmission being weak.

What I'm wondering is if a fuel injected AMC 304 is better than a i6 but not overpower the Transmission . Does fuel injection liven up a AMC 304 enough to make a swap worth it?

 

[Petescj]

I am of the opinion that a properly rebuilt T-176 will live behind a 360. The T-176 is the best Transmission available in the later Cjs. That said I think you could get some beneficial advice from these two peoples build threads and maybe reach out to both of them personally. Both are helpful people who have the e.f.i. 304s and have used them on the Colorado trail rides featured here.

https://www.jeep-cj.com/forums/f98/79-cj7-they-re-coming-take-me-away-aha-24761/

https://www.jeep-cj.com/forums/f98/operation-sky-blue-water-trip-build-21262/

 

[hagar]

Could always go air injection instead....

 

[hole]

Fuel injection will liven up the AMC 258 i6 / 4.2l and will cost far less than the swap . Beside the Transmission (of which the 176 is a pretty good one) the rest of the driveline isnt going to like the V8 without a good deal more money and work thrown at it. A junkyard MPI can be done in the hundreds, IIRC Howell throttle body injection for about $1500 and the new MPI kit from Hesco was $2500 before being discontinued. Your money, your CJ

 

[gert]

as you have found out many varying opinions out there, the I6 has a very long history of being a reliable torquey motor well suited to the CJ is was installed in, plenty of options out there, you could easily find a donor 4.0 and install your AMC 258 i6 / 4.2l crank in it to get even more torque horse power and factory fuel injection to boot

I personally like the AMC 304 when i started my build many years ago i could not find one but could find many 360s so thats what i went with, its very torquey and has the v8 horse power to boot

i like that the AMC 304 is a stock motor for a CJ so you can hit any parts store for parts and is easy swap not requiring any expensive special swap parts

i recommend the MORE motor mounts over the stock ones and a aluminum radiator as well to help keep the motor cool

you really need 1 piece axle shafts in the back and you should be good to go

also a good 4bbl intake like an edelbrock performer with 9 to 1 compression with the throttle body fuel injection will give you great performance, the stock 2bbl AMC 304 in 1971 with 8.4 compression was rated at 210hp and 300 ft lb gross hp so you will only go up from there

the AMC 258 i6 / 4.2l was rated at 150hp and 240 ft lb gross in 1971

 

[GTOgoat]

I really like the idea of the AMC 304 over the AMC 258 i6 / 4.2l for the road manners alone. From what I've read the AMC 304 makes for a better road engine but no experience with one. My experience is it feels like the AMC 258 i6 / 4.2l just runs out of steam early on the road, torque is great off the bottom but falls out soon after. Also for me, as silly as it sounds, I'm the type of person who will turn off the radio just to listen to the sound of my engine and I miss that v8 sound. I'm new to driving a CJ so all comments are a help and very much appreciated.

 

[hole]

If you still have 2:73's, I can see why you feel like the AMC 258 i6 / 4.2l is lacking some with 33's. I still run 2:73's and 32's and have little problem pulling hills at 55-60 empty, but have to pull down into 3rd (40ish) if loaded. You must have one heck of a radio in your CJ if you can hear it over the overall noise that our un-insulated tin cans produce at highway speeds. Hell, I can barely hear my buddy sitting next to me most of the time, although if I put the doors on that might improve

 

[cpadget]

I had 33's with 4.88's until I recently went to 35's. I now have plenty of power with the AMC 258 i6 / 4.2l . I am team rushed, nuttered, with a MC2150. I feel like my ratio is pretty good and very capable off-road with 35/4.88. I can pull hills in 4th and sometimes don't have to pull out of 5th. 2.73's are supper "light" for 33's

 

[007]

If you want a V8 and want to stay AMC then either is fine and your Transmission will hold them fine. No I6 is gonna sound like a V8 so that should solve that for you. The AMC 258 i6 / 4.2l /4.0 are awesome engines, but if you want a V8 and want to hear it then do it.

Bass and I both can help you with Sniper EFI. We have different setups but principles are the same. He has the two barrel Sniper and vacuum advance and I have the four barrel with computer advance. I think each of us wouldn’t do it any differently than how we did it and we are both happy so either is fine.

 

[Colorado Yeti]

I've owned 30+ CJ's in my life, both V-8 + 6-cylinders. While the AMC 258 i6 / 4.2l is a great motor with excellent reliability and off road manners I have never been impressed with it's ability to make power at highway speeds. Always have to shift down to 3rd gear going up a high mountain pass and then your lucky if you can keep > 55 mph. My tired old AMC 304 in our '76 CJ7 can do 80 mph up Vail pass without even struggling. (Wait until I build my 401!!)

Plus, you don't get that awesome AMC V-8 sound. I would pay twice as much just for that alone. But I am old school.

 

[Grumpa]

Personally, I think the AMC V8 engines sound like . They sound like a SBC with a miss to me. But whatever blows your hair back.
If your Jeep is more of a street Jeep than off road, I can see the V8 swap but if you're going to be doing more off road travelling, stay with the I6 and make the necessary upgrades for the extra "needed" power.
Me? I'm going to just run a basically stock AMC 232 i6 and enjoy it. Of course, it should be noted that I actually like the sound of a healthy I6, even if it's smaller.
I know, I'm no help at all. : (

 

[Belizean]

Heck I run a 4 cylinder with approaching 1/4 million miles. Once I get my AMC 258 i6 / 4.2l in with EFI I'll not know what to do with all that power

 

[Patrick]

Hello All,

I've searched some and cant seem to find a good answer to a question.

My goals.... Good daily driver that has the ability to go off road and do level 7 trails. And get that V8 side pipe sound!

I have a 1985 CJ7 that I want to put a v8 in and I know there are many forums on this and many on a AMC 258 i6 / 4.2l vs. AMC 304 . The Transmission I have (T-176 ) is not really strong enough for the 360/350 but will work with a AMC 304 . However, many say it's not worth the trouble to change from the i6 to AMC 304 . Also mentioned is don't bother with the AMC 304 go with the 360/350 which then circles me back to the Transmission being weak.

What I'm wondering is if a fuel injected AMC 304 is better than a i6 but not overpower the Transmission . Does fuel injection liven up a AMC 304 enough to make a swap worth it?

You will not overpower the Transmission in this case. However, if you want a truly worthwhile swap, you may as well go with a Chevy engine.

And yes, you cannot go wrong with fuel injection. It’s night and day.

 

[Lumpy Grits]

Your tire size along with the R&P ratio has much to do with tranny life.
Also, a AMC 258 i6 / 4.2l swap to AMC V-8 is a bolt in deal.
LG

 

[007]

My EFI AMC 304 sounds like a sewing machine, so not sure about the SBC with a miss.

First fire up with my EFI.
https://youtu.be/fartoxENPmo

No question the AMC 304 is better on the highway, assuming you have a reasonable gear ratio / tire combo. Either or both being off make this a non-conversation.



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