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Discussion Starter · #1 ·
Ok so I've got a Chevrolet 4.3 in my garage. I have always thought about building a 4.3 because it's basically a 350 with two cylinders cut off and it's just something different. Thinking hard of building it over the summer and dropping it in my 98 TJ over the winter. What do you guys think?
 

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A good friend of mine put a 4.3 in a 4 cyl CJ7 about 8 years ago and was a big improvement. It was a carb motor. Will you be using the MPFI on the later 4.3s?
 

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Discussion Starter · #5 ·
Yes. Gonna gut the motor down and completely rebuild it over the summer. The positives about the 4.3 are it's much lighter than a 350, and gas mileage. I'm not a big trail rider as I like to take the top and doors off and cruise with my wife and 5 yr old. I think it's gonna be a cool project
 

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I like the 4.3, it's a sweet little motor. I built one for my oldest son in an 86 full size pickup but it too was a carb motor. Ran great but wasn't the best on gas. Had 4 valve relief flat tops, a Comp 260H cam and a 500 cfm Edlebrock carb. Had 3.42 gears with 28" tires, 2wd. I'm not sure what Ricky's CJ gets in mileage but I know it made a dramatic improvement in driveablility. His also had flat top pistons but it was a newer roller cam motor so he used the stock cam and I feel like it actually runs better than my son's truck did, especially in a 4wd. He did use the 85/86 C10 exhaust manifolds that were stepped tubes from the factory. The newer engines had cast manifolds. We had a 2001 S10 Blazer 4wd with 3.73 gears, 29" tires, MPFI motor stock and got about 18 to 19 on the highway. I have a good friend with a 98 TJ, 2.5 that I am getting ready to rebuild. Jeep is great off pavement but slow on pavement with 32s, stock 3.73s and 3 speed auto. Likes gas also so I'm guessing the 4.3 would be a little better. I'm sure you will be pleased with it.
 

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Discussion Starter · #7 ·
Yeah and you can get 4.3 parts everywhere. The good thing is it's not my daily driver, just a play toy. I can spend all summer on the motor and put it in this winter. I think it will be sweet
 

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I like the 4.3, it's a sweet little motor. I built one for my oldest son in an 86 full size pickup but it too was a carb motor. Ran great but wasn't the best on gas. Had 4 valve relief flat tops, a Comp 260H cam and a 500 cfm Edlebrock carb. Had 3.42 gears with 28" tires, 2wd. I'm not sure what Ricky's CJ gets in mileage but I know it made a dramatic improvement in driveablility. His also had flat top pistons but it was a newer roller cam motor so he used the stock cam and I feel like it actually runs better than my son's truck did, especially in a 4wd. He did use the 85/86 C10 exhaust manifolds that were stepped tubes from the factory. The newer engines had cast manifolds. We had a 2001 S10 Blazer 4wd with 3.73 gears, 29" tires, MPFI motor stock and got about 18 to 19 on the highway. I have a good friend with a 98 TJ, 2.5 that I am getting ready to rebuild. Jeep is great off pavement but slow on pavement with 32s, stock 3.73s and 3 speed auto. Likes gas also so I'm guessing the 4.3 would be a little better. I'm sure you will be pleased with it.
Are you gonna put the 4.3 in the TJ for your friend? What all would you have to do computer wise and how would that be done? I want to do an engine swap into my 99 but can't decide between 350 or 4.3 or something ekse
 

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Are you gonna put the 4.3 in the TJ for your friend? What all would you have to do computer wise and how would that be done? I want to do an engine swap into my 99 but can't decide between 350 or 4.3 or something ekse
His budget is pretty tight so we are just going to rebuild the 2.5. Like you though, I am curious what it would take to put a multi-port fuel injected 4.3 in a 2.5 TJ. The 4.3 into a CJ was a big improvement over the 4 cylinder.
 

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Non aluminum 350 Chevy 520 Ish pounds

Amc 4.0 from wrangler 480 to 490 lbs

So not much real world difference

So any lift/ springs designed for a 4.0 tj should give about same net lift with the 350

Don't recommend swaps but engine weight on small block Chevy should not be a major issue

I believe the straight six that came in TJ is a pretty ideal match

4 not so much but it is far easier and not much if Any more expensive to find a deal on a six and sell the four

I once pulled the body off an early 50s jeep station wagon and put it on a mid 70 s 345 scout II as I wanted v8 auto ps power disc brakes
Spent a lot of time and was an interesting project but wish I still had the wagon in stock form with the old super hurricane straight six

The older I get the more I like the straight six design

Only straight six vehicles I still have are two TJs one yj and a 280zt turbo

Hope to one day add a oil burner dodge

To race a big or small v8 is nice but to own maintain and keep the straight six is just pleasant
 

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Non aluminum 350 Chevy 520 Ish pounds Amc 4.0 from wrangler 480 to 490 lbs So not much real world difference So any lift/ springs designed for a 4.0 tj should give about same net lift with the 350 Don't recommend swaps but engine weight on small block Chevy should not be a major issue I believe the straight six that came in TJ is a pretty ideal match 4 not so much but it is far easier and not much if Any more expensive to find a deal on a six and sell the four I once pulled the body off an early 50s jeep station wagon and put it on a mid 70 s 345 scout II as I wanted v8 auto ps power disc brakes Spent a lot of time and was an interesting project but wish I still had the wagon in stock form with the old super hurricane straight six The older I get the more I like the straight six design Only straight six vehicles I still have are two TJs one yj and a 280zt turbo Hope to one day add a oil burner dodge To race a big or small v8 is nice but to own maintain and keep the straight six is just pleasant
How much and where would a 350 be?
 

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How much are you thinking it's gonna run to rebuild the 2.5?
Not sure yet because the #2 and #3 rods are knocking pretty bad so it may need a crank. Right now with machine work and engine kit, we're expecting about $800 without a crank and an additional $125 if we have to get a reman crank.
 

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Also agree with Digger 84 in post #13. I believe the MPFI 4.0 in the TJs is about as close to perfect as we could expect. It's reliable, decent performance & decent fuel economy. I enjoyed my 75 CJ5 with a 304 V8 but the 4.0 in my 2000 TJ performs just as well, plus it doesn't stall when I'm climbing hills on a trail because there are no floats to bounce in a carb. Plus with a stock engine, if you break, you don't have to worry about special ordering conversion parts. For my friend that put the 4.3 Chevy in his CJ, it is a nice setup, but I know he spent a small fortune in conversion parts to adapt the Chevy motor to his transmission. For my friend that has the 98 with a 2.5, we actually considered a 305 Chevy because I have one that I would donate, but for him, it just really isn't worth the cost or time involved to make the swap.
 

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Pretty involved and unless you have a complete donor tj or Lj probably not most economical route

Either find a rust killed 4.0 to harvest all parts and get motor mounts welded into your 2.5 tj or fix your 4 banger till sellable and then take that money add some more and take your time and find a good 4.0 tj

If you have a really nice body and frame and are not in an emissions nazi area you could harvest all the electrical and drivetrain from a Cherokee (xj) but it would be a long slog and welding of motor mounts would be required
 
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