AMC 304 Upgrades

[Orionarms82]

Hello All,

I was wondering if you more knowledgeable Jeep folks could give me some advice on upgrading the AMC 304 in my '75 CJ5 . First, I'll tell you what I am considering. Please let me know if I'm headed down the right track, or if what I am considering is leading me towards issues. If there are any other engine upgrade suggestions, please include those too! I want to upgrade to an HEI distributor and eliminate the old ford style ignition system, install a new intake manifold, and install a new carburetor. Here are the parts I am looking at:

1. HEI Distributor CRT Performance
2. Edelbrock 2131 Performer Intake Manifold
3. Edelbrock Performer 1406 Carburetor 600cfm

Thanks!

 

[JR74CJ5]

Hey Bud!

So for the distributor upgrade:

You can do the Team Rush upgrade like BusaDave did. http://www.jeep-cj.com/forums/f2/teamrush-ignition-upgrade-11416/ But if you are wanting to get away from the ford ignition and go to a HEI distributor, there are a ton of options. However the biggest thing I can advise is either:

1. Take the old distributor gear off the old distributor, and put it on the new HEI to keep the distributor drive gear from being chewed.
2. Or get a matched set of new gears: Camshaft distributor drive gear, and gear on bottom of the distributor itself.

One of those two things will help you avoid serious issues possibly.


As far as the intake and carb upgrade. These things are all up to you and your desired gains. If you want more HP and street performance, The 4 barrel should work out great.


There were a few good posts around from Elwood Blues with CFM calculators and optimum outputs. I, unfortunately forgot to bookmark them...





~ JR

 

[GatorBate]

The BEST thing I did to my AMC 304 was TBI upgrade. I striped one off a 89 GMC truck. It was a pane in the butt to get it working But, what a difference!!

 

[jasonmark1993]

This dist. gear stuff keeps popping up.

You just need to make sure that you run a gear that is the same material as the cam gear. Im guessing it's cast iron but I don't know; just gotta run the same. I would order from Summit; their online descriptions will tell you what gear it comes with and if you look at an OEM replacement you can find out what your original engine has.


If you're going to wheel alot I'd get a truck avenger 670 by holley.

I think you are on the right track.

 

[Saddle Tramp]

Check out Junk Yard Genius for distributor tips:

http://www.junkyardgenius.com/toc.html

 

[coldair]

470 cfm carb is a really good carb for the AMC 304 . These guys that think bigger is better don't know what they are talking about. A 600 cfm is way to big for a AMC 304 they just don't flow enough even with a set of headers and intake.

 

[JR74CJ5]

This dist. gear stuff keeps popping up.

You just need to make sure that you run a gear that is the same material as the cam gear. Im guessing it's cast iron but I don't know; just gotta run the same. I would order from Summit; their online descriptions will tell you what gear it comes with and if you look at an OEM replacement you can find out what your original engine has.

Yes, I keep popping up the gear thing where ever needed.

I just had mine be chewed, and I thought I had it all figured out ahead of time.

There is more to it than just the same "type" of metal matching. There are a few different cuts available (according to the guys on Bull Tear). And if you don't change the cam one while you install a new gear the wear will not match up. It's bette to install the old distributor gear to the new distributor than to have a new "cast" to old "cast" mesh (again according to what I have read...) and "cast" is just example, not sure either what metal is originally there.

People get lucky with it all the time, and like I said I thought I had it figured out, but I was left stranded on the side of the road in the snow next to the Rubicon trail... Thankfully was not the day before when I was at Spider Lake

I'm not a "You gotta buy the Bulltear special $5000.00 gears (exaggeration) summit does offer a matched set for like $35.00 from Omix ADA / Rockyridge. This One:(broke and removed link due to product. Dist gear didn't fit dist shaft)

I figure some members would appreciate a warning up front if they haven't by chance noticed it or seen it already... Sorry if it seems I'm over emphasizing the issue... I had no idea when I first bought my jeep, then I read about it, thought I had it handled. Gears lasted me almost 9 months, thought i was in the clear, then bang.

And those gears were a PITA to find on summit. Though maybe it was just me...


~ JR

 

[coldair]

I think it's a good thing that JR keeps bringing it up he doesn't want anyone else having the same thing happen to thier motor. That's what we are all here for is to help out. So thank you JR for all you do for us.

 

[derf]

One alternative to a distributor swap is to just upgrade to the Ford TFI system. It's bolt on to your existing distributor. It's cheaper, easier and gives you similar results to HEI. The big plus is that you don't have to mess with the distributor gear since you don't have to pull the distributor at all. I did it on my 360 but the process for the AMC 304 is identical: TFI Ignition Upgrade

As far as the carburetor goes, I would only put an Edelbrock on a street only car. If you plan to take your Jeep off road at all you will hate life. I've run a Holley Truck Avenger off road and it's night and day better. The 470 CFM model will bolt up to the Edelbrock manifold and run like a champ. The 670CFM is too big, even for a 360. If you want to stick with Edelbrock carbs, the 500 CFM is a better match for a AMC 304 .

 

[CJim7]

One alternative to a distributor swap is to just upgrade to the Ford TFI system. It's bolt on to your existing distributor. It's cheaper, easier and gives you similar results to HEI. The big plus is that you don't have to mess with the distributor gear since you don't have to pull the distributor at all. I did it on my 360 but the process for the AMC 304 is identical: TFI Ignition Upgrade

As far as the carburetor goes, I would only put an Edelbrock on a street only car. If you plan to take your Jeep off road at all you will hate life. I've run a Holley Truck Avenger off road and it's night and day better. The 470 CFM model will bolt up to the Edelbrock manifold and run like a champ. The 670CFM is too big, even for a 360. If you want to stick with Edelbrock carbs, the 500 CFM is a better match for a AMC 304 .

well said on all points Derf. The TFI upgrade is ideal for many reasons. But not having to mess with the dizzy gear is like getting to skip out on a game of Russian Roulet. The upgrade is also cheap, easy to source (being stock parts), and is completely comparable in performance to the HEI.

And likewise, I would not use an Edy on an offroad machine. I put a 500cfm edy on my AMC 258 i6 / 4.2l /4.0 hybrid and it was a screamer on the pavement...not so much where inclines were involved.

A Quadrajet works extremelly well on and offroad. I ran one on my 401 and it was terrific in offcamber scenarios.

 

[derf]

well said on all points Derf. The TFI upgrade is ideal for many reasons. But not having to mess with the dizzy gear is like getting to skip out on a game of Russian Roulet. The upgrade is also cheap, easy to source (being stock parts), and is completely comparable in performance to the HEI.

And likewise, I would not use an Edy on an offroad machine. I put a 500cfm edy on my AMC 258 i6 / 4.2l /4.0 hybrid and it was a screamer on the pavement...not so much where inclines were involved.

A Quadrajet works extremelly well on and offroad. I ran one on my 401 and it was terrific in offcamber scenarios.

Yea, the Qjet is a decent carb as well. If you grab one tuned for a Chevy 305 it's not too hard to get it to run right on a AMC 304 . But it does require an adapter to bolt it to any manifold used on the AMC.

 

[jasonmark1993]

I think the dizzy gear is great info to put out because you are right, its an expensive problem to repair.

I've replaced a lot of distributors over the years and never had a problem so I am assuming that the manufacturers are just not paying attention.

 

[pc79cj5]

a good upgrade would be a set of 360-401 heads they have larger valves to let your engine breath alot better AMC 304 in. 1.787 ex. 1.406 360 in. 2.025 ex. 1.625 pretty big difference

 

[poppatello]

a good upgrade would be a set of 360-401 heads they have larger valves to let your engine breath alot better AMC 304 in. 1.787 ex. 1.406 360 in. 2.025 ex. 1.625 pretty big difference

I thought I saw somewhere that you just can't swap heads that easily. Someone correct me if I'm wrong but there are still some med to major mods that need to happen to make this swap work.

I mean I have a rebuilt AMC 304 that I'm finishing up and this is a decent idea if it can be done easy enough.

Just like others have stated what are your plans for your jeep???

 

[CJ]

Technically the heads are a direct swap (all the bolt holes are the same) - BUT - And it's a big one, unless you notch the cyl walls the valves will hit the block. And that is - BAD!

And, since you are partially shrouding the valves because of the small bore the advantage of the larger valves is somewhat negated.

 

[JR74CJ5]

Omix-Ada 17423.03 - Omix-Ada Distributor Drive Gear Kits - Overview - SummitRacing.com[/URL]

So since I have just spent the weekend trying to fix mine, i thought I'd put this out there.

The kit I mention here is

Spent all day in 104 degree driveway, and when almost done, went to install the gear on the distributor and it will not fit. I figured may have just been "tight fit" so I heated the gear up and tried to bang it on real quick, now it's stuck on my $300.00 DUI Distributor... Cant get it off. Can't get it on...

But thats another story...

Mentioning this due to the link i posted.



~ JR

 

[JR74CJ5]

I think the dizzy gear is great info to put out because you are right, its an expensive problem to repair.

I've replaced a lot of distributors over the years and never had a problem so I am assuming that the manufacturers are just not paying attention.

I apologize, I did not mean to be, sound, or appear confrontational




~JR

 

[jonboy1919]

"One alternative to a distributor swap is to just upgrade to the Ford TFI system. It's bolt on to your existing distributor. It's cheaper, easier and gives you similar results to HEI. The big plus is that you don't have to mess with the distributor gear since you don't have to pull the distributor at all. I did it on my 360 but the process for the AMC 304 is identical: TFI Ignition Upgrade"

I am all in on this upgrade, tho I just want to confirm, can it be done on a '79 AMC 304 ?

 

[derf]

"One alternative to a distributor swap is to just upgrade to the Ford TFI system. It's bolt on to your existing distributor. It's cheaper, easier and gives you similar results to HEI. The big plus is that you don't have to mess with the distributor gear since you don't have to pull the distributor at all. I did it on my 360 but the process for the AMC 304 is identical: TFI Ignition Upgrade"

I am all in on this upgrade, tho I just want to confirm, can it be done on a '79 AMC 304 ?

I believe so. I believe the Motorcraft ignition was used across all Jeep lines in 1979. I know they started with it in the full size Jeeps in 1978.

This is a picture of the ignition controller box I modified. Look for one similar to it under the hood. It won't have that big hole in the side that I cut. It will have 6 wires coming out on the right hand side next to the bolt hole. Four wires will go to one round-ish plug, two will go to another round-ish plug.

 

[jonboy1919]

I do have that Motorcraft ignition module, so yes can perform the TFI upgrade?