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Discussion Starter · #1 ·
Everybody I talk to and everything I read gets me to change my mind about everything I want to do with my CJ7. First off I want this to be a daily driver, so it needs to be decent on gas ( 12 mpg ). I also plan to use a full fiberglass body if that makes a difference. My current rear axle is a Dana 44 with 3.73's I was considering a V8 swap, and already gotten the motor (302 V8). Also needed a tranny (considering a Jeep T-5 since it should handle what I need it for, and I will need the overdrive gear), but come to find out it won't hold up to V8 power. I don't plan to do any rock crawling or hard offroading, just the ocassional beach driving and playing in the mud. So scratch the V8 idea I guess (doubt it would be good on gas anyway). I want to run 33's, and I was looking at either the 10" or the 12.5" BF Goodrich. So I need a motor that won't strain too much yet still turn some oversized tires, and then still not tear up the 5-speed while doing it. If push comes to shove, whatever motor goes on this vechile will get treated to a Holley Projection system, if it will help performance and mileage. Also plan to add a AGR steering box and pump, and a reveresed shackle kit for driveablity, even considering YJ springs to replace the CJ springs. I don't plan to run any lift on this vechile (since the 4wd hardware tub I decided on getting has a built in 2" lift). So if you had this setup, and wanted to build a motor for gas mileage what would you build? I was thinking of either the Ford/Chevy 2.8, Ford 3.8, or the Chevy Vortec V6 (not sure of the liter's 4.3 I believe) or maybe the Buick 225 V6. I want to stay away from a inline 6 (since my 80 CJ7 with the 258 I6 drinks gas like theres no tommorow). Anyone have any suggestions?

Chad
80 CJ7
84 CJ7

 

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if it were me, i'd run a chevy 4.3 bolted to an sm 420(7 to 1 first)bolted to an np208..then run dana 44's front and rear and never worry about anything

~~Elusive~~
it's sort of still a cj thingy....
 

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If I had to drive it daily...

3.8 V-6 with factory fuel injection out of junk yard,
OR,
Vortec 350 with factory fuel injection out of junk yard.
Both are dirt cheap and plenty powerful enough for a daily driver.

TH-700R-4 with working lockup converter and factory T-Case adaptor.
Low first gear, Over Drive, Lock up for economy. The TH-700R-4 is tough and dependable, and very fuel efficient.

NP T-Case.
Everywhere and cheap. Came out stock in millions of chevy trucks. Not a power hog.

Factory Jeep axles.
Reasonable shocks, wheels & tires. (sensible shoes...)

Just my $0.02 worth...
It's worth what you paid for it...
Aaron.

If Chris Columbus "Discovered" America (with 25 million already here), Can I Go "Discover" Florida?
 

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I think T-5's came behind 302's in Fords. Will probably stand up to a 302 sans abuse. For fuel economy any overdrive tranny, and a lockup torque converter with an automatic. For an engine.......fuel injection, fuel injection, fuel injection. Had a 4.0 in a Jeep p/u. Got 25 mpg on highway. Good Luck. Jimmy Z.

 

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Not a big 4.3 fan. Not because I know any big secret, just out of ignorance.
I don't do many 6 cylinders at all, so I don't keep up on them.

I have had two girlfriends that had 3.8 V-6 engines, both went 150,000 without complaint, both got outrageous milage, both made bucket loads of horsepower for their size. Both looked fairly easy to work on... (although I never had too.)

The fuel injected 3.8 with TH-700R-4 w/lockup and NP transfer case in one package is available in any junk yard in any type of 4X4 from GM, so they should be cheap.
Lots of rich people's kids wrecking 'SUV's' every day.... Good low milage isn't hard to find.

The average Vortec V-6 pickup engine complete, with wiring harness and computer is going for around $1,000 when you can find them, and they are showing up every day.
I just bought an entire 350 Z-28 drive train with all engine accessories, computer, transmission and all for $750. Under 5,000 on the clock.
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I prefer the transfer case my buddy has in his chevy truck now... (What ever was stock in 89 behind a V-8)
Shifts on the fly, even at 60 mph, has a stand alone control mounted on the floorboard 'hump' that could be transplanted to a CJ-7 really easily...





If Chris Columbus "Discovered" America (with 25 million already here), Can I Go "Discover" Florida?
 
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Discussion Starter · #8 ·
I also think the 3.8 (or 3800 as it is currently called) is a great engine. You'll need one from a rear-wheel-drive Camaro or Firebird as it is mainly a front-driver (Regal, etc.) & was never offered in a pickup or SUV. The 4.3 is also a good choice, but probably won't give the same kind of fuel mileage (most folks I know with 3800's average 27-35 MPG on the highway in cars with REALLY overdriven gearing). Not sure I agree with your theory of a V-8 being necessary for rocks, but not mud or sand (I'd say just the opposite), but either of these 6's will turn 33" radials just fine in a light CJ. You should probably consider a TH700 tranny & if you want to get one with a T-case attached, you can get a 1/2 ton GM TH700/NP208 combo from '81 to '87 or a 1/2 ton GM TH700/NP241 from '89-'91 in straight-axle Blazers & Subs. Freshen that tranny up while it's out. 4th gear is a radically steep .70 overdrive, which would make 4.10's (with a 1:1 top gear) seem like 2.87's in overdrive. If you can't afford a set of 4.10's (or something similar) for now, run around with some stock 3.31's or something in "drive". Forget lockers & Dana 44's. This is a daily driver & light-duty sand/mud runner. That stuff just isn't necessary for such light-duty chores - especially with a V-6. A Dana 30 front in good shape will be fine, as will a stock 44 or 20 rear if you treat them well. If you have wide-track axles, consider the 10.50 wide tires to keep 'em up under the fenders a bit better. I'd go with 8 or 8.5" rims so if you pick one tire width & decide to change that on the next set, you'll have wheels that'll work for 10.50's OR 12.50's. One other thing, topless Jeeps are "cool" /wwwthreads_images/icons/cool.gif, but not cool in the summer. If it's hot where you are, try to set that sucker up with A/C even if you plan to run around topless. Retro-fitting A/C is something I've never known much about, but it MIGHT make sense to get as much of the A/C stuff from the engine donor vehicle as possible??? Put the cheapest stereo in it you can imagine (so if it gets swiped, you won't care) & go have some fun. Just my $.02.

TEX

/wwwthreads_images/icons/wink.gif Got Mud?
G.U.M.B.O. Mud Racing
 
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Discussion Starter · #9 ·
Would a 4.3 litre V-6 bolt up to a th350 trans? I am heading toward a V-8 swap, but it still isn't too late to change my mind. This
Jeep will also be a daily driver and needs to get good gas mileage. What kind of power can I expect to get out of the 6? And how
much would it cost me to get it in my Jeep, including purchase price, wiring, etc?
Dan

 

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yes i agree with the v-6 choices.. but i also dont know what you have to spend.. you said this is a daily driver? i would drop that 302 in it.. bolt up a good t-5 and be done with it. if you are worried about the ability of that t-5 talk with Elusive.. he has ran one behind a high hp 304 for a year now.. and has had no problems..and i am talking about 350 or so horses.. turning 5-6000 rpms.. rocks, mud, what ever he can get into. So i think they are a decent tranny... especially for a daily driver.. then take that money you just saved and get some nice 33x12.5's on some 8" rims.. keep your stock axles.. you do not sound like you are going to beat the snot out of this. so keep the stock ones.. you should be happy.. have known many people with this set up and they have liked it. good luck..


survival is instinct, but living takes guts
 
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Discussion Starter · #12 ·
Has anyone on this BBS transplanted a 3.8 into their Jeep? If so, I'd like to get the particulars on the transplant, especially the headaches. We had an Olds 3.8 that gave high 20 mpg figures.

 
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Discussion Starter · #13 ·
I have a Buick 3.8 in my Jeep. I only get 14 mpg, but that is also due to the tranny. The biggest problem with the Buick is that I like manual trannies and the one that was cheapest to put on is was the M21 which has a horrible first gear. I'm going to swap in a NV 4500, but the adapters to the engine is going to cost me around $500. I'm thinking about putting a Chevy 350 or 383 in instead. If you want a automatic the swap probably will not be as bad. Also the 3.8 can be upgraded to make a good amount of torque without spending alot of money.

Tim Springer
1980 CJ7
WALSTIB/wwwthreads_images/icons/wink.gif
 
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Discussion Starter · #14 ·
If your gonna run a chevy V-6 I would use the 4.3 sense it is a much more common swap in to a jeep and your choice of trannies is better. I like the jeep 258 if its done right, my dad ran an 85 CJ-7 with Jacobs ignition, gibson exhaust, K&N filter, T-5 tranny 4.10's and 33's. he ran this setup for a few years and it got 20-23 mpg, even better then the 93 wrangler he has now.

Jeff
'83 Toyota long bed
5" lift, YJ front springs
 

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Hey, the 258's a good engine..... adequate torque, reliable, easy to work on, lighter than a V8 and fits in the engine compartment better. I seriously doubt you'd get any better mileage with a different engine..... you're still pushing a big box through the air, that takes fuel.

20-23mpg in a CJ7 with any engine sounds a little unbeliveable, though.

-Dana

"Very funny, Scotty. Now beam down my clothes."
 

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Believe it, 20 mpg with a 305 TPI and T176. Not only that, the local Mustang, Camaro and Firebird
owners have learned not to try impressing their girlfriends by trying to beat the Taz Jeep away from a
traffic light. I had two different 258s in the same Jeep and BEST I saw with them was about 17 mpg.
Forget the wimpy 6's and go for the gusto.


 

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ummm.. the 258 is not lighter than a 302

~~Elusive~~
it's sort of still a cj thingy....
 

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"More power" and "Gas mileage" don't go together IMHO. You can buy a lot of gas with the money you'll spend on some exotic engine/transmission/transfer case swap. For a daily driver keep it stock and well tuned.

I guess I'm and old fart.

Loose nut behind the wheel
Another right-wing conservative.....
Born and raised in Jeep-Town
 
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Discussion Starter · #19 ·
I think I'm going to reconsider my views on the Chevy 4.3 V6. I checked into rebuilt kits (Pistons, cam, lifters,rings, bearings...etc)and it's priced well under $350 from Northern Auto parts. Would I have a hard time adapting the Jeep T-5 to a 4.3? Anyone have any suggestions to which on I should try to find in a junkyard? Which Chevy vechiles came with this motor? I'd prefer a roller cam motor is there is one. Anyone know the HP/Torque specs of this motor? With a 5-speed, 33's and 3.73 gears would this be a better choice than a V8? Thanks

Chad
80 CJ7
84 CJ7

 
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Discussion Starter · #20 ·
Loosenut, I would keep it stock with the exception of one little problem, I bought my 84 CJ7 minues a motor (factory 151 4cyl). Even if it still had the motor I would want to switch it out over a V6/V8. Would I also need to replace my driveshafts (since it was a factory 4cyl) when I goto a larger engine?

Chad
80 CJ7
84 CJ7

 
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