Engine Conversion- What is better? 4.0, 4.3, or 5.0 in a CJ7 - Pirate4x4.Com : 4x4 and Off-Road Forum
 
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Old 07-21-2006, 07:59 AM   #1 (permalink)
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Engine Conversion- What is better? 4.0, 4.3, or 5.0 in a CJ7

Looking into different engine swaps/upgrades for my 78' carbed CJ7. Here are the options I have looked into so far:

4.3L Chevy V6 w/ 700r4 or newer auto tranny
5.0L Chevy V8 w/ 700r4 or newer auto tranny
4.0L head on my existing 258 motor and auto tranny

I will be using it for trails and daily driving. Looking at all that will be needed in a Chevy conversion for the cost is it worth it all in the long run. Main goal is to get better performance and get rid of the carb.

Thanks,
Jeff
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Old 07-21-2006, 08:11 AM   #2 (permalink)
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I've driven all three engines in a YJ, as well as the 258 in a CJ.

My favorite is the 5.0. Lots of fun.

The 4.0 and the 4.3 are both great. I liked the 4.3 on-road better, and the 4.0 off-road. 4.0 had an AX-15, 4.3 had a TH350, 5.0 has AOD.


6 of 1, half a dozen of the other, really. What ever you can get the best price on.
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Old 07-21-2006, 09:07 AM   #3 (permalink)
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i went with a chrystler 5.2 (318) and the 46rh outtah a ZJ. no adapters necesary to adapt it to the cj7 d300 and i gained an OD. motormounts, crossmemeber, wireing... done.

would do it again in a heartbeat.

either that, or a 258 stroker.
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Old 07-21-2006, 09:08 AM   #4 (permalink)
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If you are looking at the chevy, why not just go with the 5.7 and be done with it?
I'm running a TBI'd vortech 350 mated to a 700r4 in my old CJ and couldn't be happier with it. The swap is going to cost you about the same either way you go, so why not get the most motor for your money?

I will say, in hindsight, I might have avoided fuel injection altogether if I had it to do over again. I haven't had one problem our of my TBI and it runs perfect, but in the back of my mind I am always paranoid that the mysterious black box is going to fry and leave me stuck in the middle of nowhere.

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Old 07-21-2006, 09:12 AM   #5 (permalink)
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I would 2nd that.

When you buy from someone in the hobby, they'll charge more for the bigger motors....

but...

when you go to junkyards, they pretty much will charge the same for a 350 as a 4.3, and the 350s are so plentiful.

Around me, I can get an iron block 5.3 vortec with ~50k miles for $600 from the local junkyards. Or a 4.3 for the same price..

V8 torque is nice, you can go through everything smoothly.

I had been running a 304 in my last Jeep, now I'm wheeling a Toyota with a 22RE. The toyota has enough power on the trail, and WAY better gearing than the Jeep. But I'm always up in the 3000-5000 rpm range with the toyota.. way to often. I love 4 cyls, but as I'm building my flattie, its getting a 4.3 to start, and hopefully convert to a 5.3 newer vortec or a 5.7 vortec later..

Driving the trail with small throttle inputs is better than having to hamme rit all the time.
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Old 07-21-2006, 09:21 AM   #6 (permalink)
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Quote:
Originally Posted by Jerry Blair
I've driven all three engines in a YJ, as well as the 258 in a CJ.

My favorite is the 5.0. Lots of fun.

The 4.0 and the 4.3 are both great. I liked the 4.3 on-road better, and the 4.0 off-road. 4.0 had an AX-15, 4.3 had a TH350, 5.0 has AOD.


6 of 1, half a dozen of the other, really. What ever you can get the best price on.
Based on the original post, it looks like he's talking about the chevy 5.0, the 305. If that's the case, I would run the 4.3. I know a few with the 305 chevy and all of the owners hate 'em.
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Old 07-21-2006, 09:24 AM   #7 (permalink)
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Quote:
Originally Posted by Haggar
I would 2nd that.

When you buy from someone in the hobby, they'll charge more for the bigger motors....

but...

when you go to junkyards, they pretty much will charge the same for a 350 as a 4.3, and the 350s are so plentiful.

Around me, I can get an iron block 5.3 vortec with ~50k miles for $600 from the local junkyards. Or a 4.3 for the same price..

V8 torque is nice, you can go through everything smoothly.

I had been running a 304 in my last Jeep, now I'm wheeling a Toyota with a 22RE. The toyota has enough power on the trail, and WAY better gearing than the Jeep. But I'm always up in the 3000-5000 rpm range with the toyota.. way to often. I love 4 cyls, but as I'm building my flattie, its getting a 4.3 to start, and hopefully convert to a 5.3 newer vortec or a 5.7 vortec later..

Driving the trail with small throttle inputs is better than having to hamme rit all the time.


Flatty....Mmmmmmmmmm.
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Old 07-21-2006, 09:48 AM   #8 (permalink)
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5.7 is another option

A 5.7 is another option also. I just want to be sure that what ever conversion I do will give me the most bang for the buck. I am also worried about having to spend extra cash on axles, etc. due to a larger motor breaking things after the conversion. I am not at this point a crazy wheeler but who know what will happen down the road
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Old 07-21-2006, 06:12 PM   #9 (permalink)
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Yeah, some info on the rest of your rig would be helpfull
I did a 4.0 headswap on my previous 258 and the hp/torque increase was amazeing. granted, i was also starting with a block that i had already installed a 260* cam and flat pistons into, but i could really tell the difference. Running the 4.0 head along with a 500cfm Edelbrock, XJ header, TFI, along with the other upgraded parts i was running more hp then most stock V8s and i kept my lowend torque. But i was still limited by the 4.2 RPM range which kills any sort of highway driveing with a compound low 4spd and lower gears...if thats anything to consider in your case.
The nice thing about the headswap is not haveing to mess with the rest of your drivetrain. Short of building a stroker, thats the best thing you can do to an inline 6.
I coulda put a SBC in, but powering up an otherwise slug of a motor was more fun.
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Old 07-21-2006, 07:37 PM   #10 (permalink)
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Quote:
Originally Posted by Haggar
I would 2nd that.

V8 torque is nice, you can go through everything smoothly.

I had been running a 304 in my last Jeep, now I'm wheeling a Toyota with a 22RE. The toyota has enough power on the trail, and WAY better gearing than the Jeep. But I'm always up in the 3000-5000 rpm range with the toyota.. way to often.

I love 4 cyls, but as I'm building my flattie, its getting a 4.3 to start, and hopefully convert to a 5.3 newer vortec or a 5.7 vortec later..

Driving the trail with small throttle inputs is better than having to hamme rit all the time.

Since you love both 4-cyls and torque, I'd think you'd love a diesel...maybe the bigger Isuzu 4-cyl turbo out of an NPR truck? Pretty flat torque, from idle to full rpm. Gearing might be an issue tho, I suppose...

For anyone stuck on a V8, I really like sceep's swap....the 5.2/tranny right outta the ZJ. Get's 20+ hwy mpg in a ZJ...can't be much worse in a CJ....and it's reasonably stout stuff.

As far as worrying about EFI, cuz your box might fail, I don't understand that. Ya carry spare U-joints, right? Can't ya carry a spare box?

I picked up a used box for my ZJ for 50 bucks; and tossed it in the parts bin in back. Now I don't ever worry about the box. Not that I've had a single glitch in 175K miles; but they do break like anything else, sure.


OK, for the guys who like 4-bangers....what about the Saab 900 turbo engine from the early 90's ??

My bro on the other coast is a Saab nut...900's, old Sonnets, whatever. It's a disease. Anyway, he tells me that that 900 turbo motor puts out 220hp, and around 200 ft-lbs even as low as 1800 rpm. Hell, that's as good as the 5.2 !

Not sure of the weight; but I'm thinking it's quite a bit less than a jeep 6.

And your mpg's on the road ought to be pretty good too.

Don't know how you'd do to hook it into the jeep tranny, but hey, it can't ALL be bolt-on, right?
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