Engine More Power for my CJ7

[oldcj7guy]

1979 CJ7 . I want to replace the AMC 258 i6 / 4.2l with something more powerful. Less than 100 hp and less than 200 lb/ft doesn't do it for me. I want to drive 35's on it and have plenty of torque for off-roading and speed for highways.
I've looked at Golan's 4.6L Stroker. It seems to have the level of power and torque I'm looking for (<300 lb/ft and 275 HP). That one is interesting because little modification should be needed for a swap. But... it costs 10K.
I'm not interested in the LS1 because I don't need that much power and I don't want to have to do a lot of mods.
I'm wondering how much trouble it would be to modify my present AMC 258 i6 / 4.2l to get what I want. Is there a kit? Has someone documented a similar project? Suggestions?

 

[Manic Mechanic]

Do you know about how long the driveshaft would be?

No you'd have to measure that will change depending on lift final location of Transfer Case and pinion angle

 

[Belizean]

Once in a while you get lucky. I went from AMC 4 cyl. T-4 . Dana 300 . to AMC 6 cyl. T-176 Dana 300 . and reused both drive shafts.

 

[Manic Mechanic]

Once in a while you get lucky. I went from AMC 4 cyl. T-4 . Dana 300 . to AMC 6 cyl. T-176 Dana 300 . and reused both drive shafts.

Factory engine options to factory options yes. But what he's talking about more than likely no

 

[TSB8C]

Can anyone tell me how tight the fit would be with LS1-4L60E-Dana 300 -Dana 44 ? I heard it might be a little too tight.
1979 CJ7

The LS1 is 28" long and the 4L60E is 21.9" long). I'm running an SBC (28.5" long) with 700R4 (21.9" long), then a Novak adaptor and the Dana 300 . So almost identical to what you described. I have a 4" lift making the rear drive shaft somewhat short and angled. Had to lengthen the front shaft and shorten the rear a bit, but it all fits and works. The spring perches on the rear Dana489 (heavier Dana 44 ) axle are angled (you could use shims) to move the pinion up a bit and I have no issues with drive shaft vibration at high speeds. Under the hood is a bit tight. I also have a serpentine belt kit, which took up some space. The LS would be the same. I used slim electric fans from a Ford Contour as no mechanical fan would fit due to Limited space. With EFI, I wanted the electric fans controlled by the ECU anyway.

I have a Lokar shifter on the tranny and the twin-stick kit for the Dana 300 allowed me to position the shifters where I wanted since things are back a little further than stock. I also got a blank tunnel cover so I could cut my own openings for the shifters. Also had to drill new holes for the rear tranny mount in the skid plate, but plenty of room with no issues. The frame already has the mounting holes to move the plate back some if needed (depending on where you're at now).

I've got dual exhaust inside the frame rails and out the back with no issues. No issue with the steering shaft hitting the exhaust (some people run into this depending on header types). No issue with the front drive shaft hitting the tranny pan (probably would without the lift). I did move the charcoal canister to the space behind the rear wheel well (where the rollover check valve is located). I also used an electric fuel pump inside the tank (didn't like the noise of an external frame mounted pump).

A good setup with plenty of power, plenty of torque, lots of versatility and parts availability with the Chevy drive train, quite reliable, and fun to build and drive.

 

[TSB8C]

Do you know about how long the driveshaft would be?

I'll measure mine later today and give you those lengths. The setup you're describing would be very close to mine (35's, same drive train length, etc). I have a 4" lift. My spring perches are angled 4 degree up and I also used drop spacers on the skid plate to angle the rear output of the xfer case down. But your rear pinion angle and amount of lift might make a difference. So as Manic said, get it all in place, then measure the final lengths needed before you change your drive shafts.

 

[CJ]

Do you know about how long the driveshaft would be?

It would have to be measured appoon the situation.

 

[oldcj7guy]

I'm just trying to get a ballpark estimate to help me decide on drive train components. I don't really want the driveshaft too short.

 

[TSB8C]

My rear drive shaft is 22.5" and the front is 35.5". That's eye-to-eye centered on the shaft "eyes" where the u-joints mount.

 

[oldcj7guy]

Thanks much!

 

[oldcj7guy]

Decision made. LS5.3 60,000 miles, $4500 for everything, electronics, harness, sensors, starter, etc.

 

[TSB8C]

Decision made. LS5.3 60,000 miles, $4500 for everything, electronics, harness, sensors, starter, etc.

Let the fun begin!

 

[Manic Mechanic]

Not bad. At that mileage I'd drop it in and run with it. I've seen LS engines with 200k miles look almost new inside

 

[Kweimer]

I have a nice setup in my 85 CJ7 , might be worth looking into, im running a clifford 4bbl intake, a holley 390cfm 4bbl but a 470 truck avenger donated some parts to it. Stock exhaust manifold currently, and a davis unified HEI distributor, I have 4.56 gears in my axles. I saw you wanted to run 35” tires so might be worth looking at 4.88 but i imagine the 4.56 would do alright as well Im running 33x12.50r15 mickey thompson Deegan 38 MT tires. I have the T-5 manual. I have no lack of power, and the setup im running consistently gets 20mpg hand calculated fill up to fill up. The trick is getting the carb jetting right and the secondaries set properly, once the carb is dialed in it starts easy, has plenty of power, idles well, and has proven to be a solid reliable configuration.

 

[Kweimer]

I have a nice setup in my 85 CJ7 , might be worth looking into, im running a clifford 4bbl intake, a holley 390cfm 4bbl but a 470 truck avenger donated some parts to it. Stock exhaust manifold currently, and a davis unified HEI distributor, I have 4.56 gears in my axles. I saw you wanted to run 35” tires so might be worth looking at 4.88 but i imagine the 4.56 would do alright as well Im running 33x12.50r15 mickey thompson Deegan 38 MT tires. I have the T-5 manual. I have no lack of power, and the setup im running consistently gets 20mpg hand calculated fill up to fill up. The trick is getting the carb jetting right and the secondaries set properly, once the carb is dialed in it starts easy, has plenty of power, idles well, and has proven to be a solid reliable configuration.

On a side note it might be worth looking into the offenhauser 4bbl intake as its dual plane where the clifford is single plane, my jeep came with the clifford when i bought it, id have probably bought the offy intake had i been spending money on it, the single place can make cyl 1&6 run lean, i am running a 2x9” k&n filter in a stainless marine housing as well. You will want a carb spacer probably about an inch tall to isolate the carb from the heat of the manifold somewhat, the factory jets in the holley carb will be too large i can look into what im using if you decide to to that route but elevation will make a difference and my settings should only be used as a reference starting point.