I also have a 1983 CJ7. I bought it used in 2013. It has a 4.2 liter engine with a 4 liter head. It came with the factory Mopar Multipoint fuel injection kit already installed. I also have a T5 transmission. My Jeep has run great for the last 8 years with no problems. This kit is smog legal in California. It has plenty of power and is great off-road going up and down steep inclines. I don't know how much horsepower gain there is but I think that the EFI conversion is the way to go.

 

Thanks for the info. I have read about the Mopar EFI kit. Does it bolt on the stock intake from the 4.2? Is it less expensive than the EFI kits from Holley or Howell? I would like to convert to EFI at some point, but installing the factory EFI system from a 4.0 seems like alot of work. I think an aftermarket kit would be the way to go.

 

While this idea may be more involved, what about a stroker engine? Using a 4.0 block & head with a 4.2 crank you can build a nice 4.5-4.8 engine that supposedly has both the torque of the 4.2 with the horsepower of the 4.0 while still looking fairly stock, the added benefit is that you can get OEM fuel injection at the same time. The nice thing is that it looks like it would only cost the additional 4.0 engine. I personally am leaning that way as my 4.2 isn't sounding so good, I just need to start looking for a cheap 4.0. There are forums out there dedicated to the stroker engine so there is a lot of support available.

 

thanks, I was reading alittle bit about strokers last night and was going to look them more this evening. Sounds interesting. I would just need to get a complete 4.0 rather than just a head. It is food for thought

 

thanks for the info. I have read about the Mopar EFI kit. Does it bolt on the stock intake from the 4.2? Is it less expensive than the EFI kits from Holley or Howell? I would like to convert to EFI at some point, but installing the factory EFI system from a 4.0 seems like alot of work. I think an aftermarket kit would be the way to go.

 

I have all sorts of ideas running through my head. LS swap, rebuild the current engine, EFI conversion etc. From what I understand, the T5 transmission will not hold up to a Chevy V8. My current thought is to build up the 6 that is in it to get the HP I need out of it. From what I gather, the 4.0 head will bolt on the 4.2 and provides a tremendous increase in HP. One can get all the necessary pieces and add the EFI system that came with the 4.0, or get an intake manifold that will accommodate a carburetor, or even port the manifold from the 4.2 to work on the 4.2. There is at least one thread on this topic, but it is 15 years old and none of the links work anymore. Does anyone have any thought on this conversion? Any help/advice would be appreciated. Thanks

How much HP do you need. Really? An old, well broke-in, but good running 258 makes about 100 HP and about 200 ft/lbs torque, which has been enough power to move a Jeep down the road, since they were new. If you increased power output 25% by installing a 4.0 head, you would have about 125 HP, to me it’s not worth it, but to some I guess it would be great. That’s probably about what the Mopar EFI kit gave you.

The Mopar kit is no longer available, so the easy 25% increase from the kit, is a thing of the past.

I built a 4.7 for my rig, after doing some research. I put some time and effort into my engine, It makes torque right off of idle, plenty of power for a CJ-7. It’s the perfect engine that AMC or Chrysler should have built and installed in Jeeps from the factory.

 

How much HP do you need. Really? An old, well broke-in, but good running 258 makes about 100 HP and about 200 ft/lbs torque, which has been enough power to move a Jeep down the road, since they were new. If you increased power output 25% by installing a 4.0 head, you would have about 125 HP, to me it’s not worth it, but to some I guess it would be great. That’s probably about what the Mopar EFI kit gave you.

The Mopar kit is no longer available, so the easy 25% increase from the kit, is a thing of the past.

I built a 4.7 for my rig, after doing some research. I put some time and effort into my engine, It makes torque right off of idle, plenty of power for a CJ-7. It’s the perfect engine that AMC or Chrysler should have built and installed in Jeeps from the factory.

Can you tell me about your 4.7?

 

A 4.0 head is quite easy to install, you will also need the exhaust manifold. All well documented on the Forum. Opinions vary on how much difference it makes on the 258 by itself. If you can find a cheap head and manifold, about $300 and a day.

The 4.0 head has a better flow but you really need to look at the cam and ignition and headers and fit fuel injection to get the best out of it. The 4.0 is a shorter stroke so will rev higher but the 258 is better suited to a CJ and will perform almost as well as long as these matters are taken care of.

You can out a basic GM type throttle body inection on. Howell produce one. Nothing fancy but it will start and run better. All up $1500 -$2000.

If you decide on a Mopar injection setup, then you need the manifold, injectors, throttle body, computer etc from a Wrangker or Cherokee or Grand Cherokee and to fit a high pressure fuel pump. All of this is doable and it will control the ignition timing. It is a better setup with a dry manifold and multipoint injection. All up $1800 to $2300

A stroker is an excellent suggestion. You need a 4.0, preferably a Mopar injection equipped HO. Put in the 258 crank and new rotating parts and you will get something which is long stroked but giving more than a 4.0. can give in a CJ. All up $2000 to $2500

 

Mine is based on a 1995 Cherokee 4.0 because I used the (entire) engine wiring harness, ECM & PCM from a 1995 XJ with a manual transmission. There are about five or six wires that must be connected from the CJ-7 firewall plug, to the XJ harness. This is known as “Five to Fire”, and if you Google it you will get a lot of hits. Once you make these connections the newer fuel injected engine doesn’t know it’s in a CJ. So that’s the electrical part of the swap.

Mechanically the 1991-1995 4.0 engine parts are all interchangeable. There are other year parts that work as well, but I’ll try and keep this condensed, you can research more if you like.

I used a 1993 4.0 block, bored .060” to 3.935”, and a 258 crankshaft with a stock 3.89” stroke. This gave me a displacement of 284” or 4.7 liters.

I used a “0630” head from a 1996-1998 4.0. I ported my head, and installed oversize Manley SS race valves for an LS1, along with beehive springs.

I used a Banks SS header, and custom built a 2.5” exhaust, with a hi flow cat & muffler, 2.5” all the way through to the tail pipe.

I bought my custom pistons, rods camshaft and valve train parts from Russ Pottenger, at Bishop-Buehl Racing Engines in CA. When I decided to build this engine I called Russ and told him what I wanted to do, and he put together a package for all the parts. That alone cost about $1700, but it was a proven combination of parts, from a very competent engine builder, so it was money well spent.

I spent about 3K on the engine and about 1K on new or upgrades to my CJ-7 while doing the engine swap. I wanted the new engine to be maintenance free, so I replaced stuff that didn’t necessarily need to be replaced.

In the end, I have a new engine (OBD-I) that has computer controlled EFI, and it doubled the power output of the 258 easily, probably a little more. I have an automatic transmission and 273 gears, on stock suspension with 31” tires. It’s a little under geared, but the torque converter works it’s magic and launches the Jeep with no problem. 331’s would probably be perfect for the current combination, but I’ll run it like it is for now.

 

Thanks for the info. I think the 4.7 stroker is the way to go. as my father used to say, "There's no replacement for big displacement" From what I gather, a 4.7 stroker will put out about 230 hp and over 300 ft/lps of torque. That is plenty for what I intend to do with my CJ. I also have long liked how smooth an inline 6 cyl runs compared to a V8, So I really like this idea. I am still pondering what engine management system to go with. I have always preferred EFI over carburetion, but for this Jeep, I am looking for simplicity and trying to keep it from being a bottomless money pit. Clifford makes a nice intake for the 4.0 head that will accommodate any carb or aftermarket EFI system one wanted to run. they also make one for twin weber carbs. But for that kind of money, I think I would go with some type of EFI. Was installing the entire EFI system from the XJ alot of work? It seems to me that a Holly or Howell EFI system would be much easier and simplistic.

 

I didn't know that the Mopar factory kit is no longer available. With the kit you had to install a new intake manifold, crankshaft dampener, distributor and other parts.
Good luck on your build.

 

250 HP & 325 FTLBS is probably close to what mine makes. Russ picked the Comp Cams 68-236-4 grind, to go with the ported 0630 head with oversized valves. I also put a horseshoe intake on, from a newer 4.0 engine, with a BBK 62MM throttle body.

Installing the 4.0 wiring harness was really pretty easy, after I figured out where to mount the ECM (drivers side firewall) and the ECM (adjacent to the battery tray). I laid it in place and started connecting what I knew needed to be connected. There are a lot of connections that do not get used when you put the 4.0 into a CJ.

I did have a buddy, Lee do the final ”five to fire” wiring connections or spices for me. He is a career electrician and a Jeep enthusiast, he races XJ’s in local competition. Lee has done the five to fire many times on other Jeeps, and he wanted me to port a head for his YJ, so I couldn’t pass up the barter, knowing he would do it, and do it right the first time.

When the day came to wire the Jeep, Lee and his wife ran the wires, checked the wires, and proceeded step by step, and made all of the required connections. He was on the drivers side, and she was on the passenger side. They used a Fluke meter, and he had the wiring diagrams on his laptop, sitting on my toolbox. I fetched tools & beer when required. After about four or five hours all was connected with the exception of the speed sensor from the transfer case.

Lee said it should start now. He connected the battery and told me to turn the key. It fired right up! I shut it off after about ten seconds with a huge smile on my face.

I still need to port his head…lol

I hate porting cylinder heads, it’s a dirty messy job, and after a couple hours of grinding I always wonder why am I doing this. I have about 20 hours in my head, but in the end, it is free power, all you have to do is be willing to get dirty and make it happen, so that’s what I do.

The best part about this engine is the way my CJ-7 drives now. It has all the power you need in a Jeep. You step on the gas and it goes, it is a joy to drive. And like you mentioned, smooth as silk. I love it when I am sitting at a red light in the slow lane, and the car in the fast lane next to me has no clue what is going to happen when that light turns green…lol. Even with 273 gears I have smoke checked many unsuspecting victims.

There is a traffic light on the way home from work, where the left lane is supposed to be turning into the YMCA after the light, but everyone knows you can get in the left lane, instead of sitting in the right lane behind a line of cars going straight. When the light turns green all you have to do is hit the gas hard, and pass the car in the right lane as you go through the light, and then change lanes back to the right lane, as you pass the entrance to the YMCA, and now you have just passed a bunch of cars…people do it all the time, me included, depending on my mood.

Recently I was sitting in the right lane and a newer Dodge truck pulled up in the left lane. When the turned green I was gone, and that Dodge was accelerating fast next to me in the left lane…lol. I gave it more gas and he couldn’t pass me. He didn’t turn into the YMCA, he had to slow down and change lanes behind me.

I laughed and thought to myself “You just got passed by a CJ-7”.

I love driving my CJ-7, I really do.

 

 

That's a nice clean set up. If I could get a deal on a wrecked EFI 4.0 jeep, I would go that route. I did find a company that makes an aftermarket head for the 4.0. they say it addresses issues the original heads had, fits all years and has the biggest valves offered, and have bigger ports. It sells for $599 complete with valves and springs. I have heard of "porting" heads, but I have never done it. I assume it involves grinding the ports bigger with a die grinder. It seems one could easilly reduce a head to scrap metal if they did not know what they were doing. I don't think I would try it. I got the spark plugs out of my 258 last night, sprayed some WD40 down the cylinders and it turns over. I will be running a compression check sometime this weekend. I am hoping that my engine will run. Than I can enjoy my jeep and keep my eyes and ears open to find the parts I need to build the perfect engine at my leisure.

 

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If you look at the picture of my engine compartment you will see a plastic bag tie wrapped adjacent to the master cylinder. That group of wiring & connectors would be going through the firewall on an XJ, providing power to the interior gauges and whatnot, but it is not needed in a CJ. There is another bag of wires adjacent to the battery, again, not needed in a CJ. There is one more bag of wires & connectors adjacent to the back of the alternator which cannot be seen in this picture.

if you look at my firewall you can see the OEM CJ-7 wiring harness (small one). The big fat harness is the XJ harness, full of a lot of wires that are no longer used. I plan on going through both harnesses and thinning what is not needed one day, and combining them all into one. For now, it will remain as pictured.