I am thinking of going the Vortec 4.3L route

My '63 CJ does not have an engine in it, so I'm not sure its considered a "swap" but I am looking to do some rock crawling.

I am thinking of going the Vortec 4.3L route and getting a donor vehicle. I believe the MPI Vortec ('96 & newer) would be the best choice. Do you agree or would the TBI be better ('95 or older)? I only have knowledge in the inline 6, so any help is appreciated.

Also, what about the ECM (computer)? Does that need to be reprogrammed and who would do that? Is it expensive?

Thanks

 

You need to reprogram the computer it you use it on a different type of engine; ie the GM 4.3L computer used on a Jeep/AMC 4.2L inline 6. If you are keeping like parts with like, you will not need to reprogram.

 

Another thing that I didn't think of...the fuel pump. Is this a major issue, or would I be able to take the pump from the donor vehicle and stick into my gas tank?

 

If my jeep didn't have a motor (and I wasn't in love with the 225 of) I would use the 4.3 TBI. I think the TBI is simpler and less trouble than the MPI. And cheaper.

I'm not sure on the fuel pump. Didn't some the TBI's use a frame mounted pump instead of the in tank style? That could be another example of an advantage of the TBI.

 

What about the emissions stuff on the computer? I don't plan on having a cat converter. Would it still run fine? Or would reprogramming it get rid of the emissions crap?
It looks like I may have found a donor 1998 Astro Van with 80K miles. I'm just trying to figure out what problems I will face (like changing the engine mounts).

 

The 96 and newer GM 4.3 and 5.7 have a different crank and different firing order than the 95 and older. The bottom end is quick to go out on the 96 and newer. I've also heard this from several mechanics. I had to rebuild my 5.7 with very little mileage on the engine that was in the vehicle when I bought it. The original engine had already been replaced at least once before I bought the vehicle. In the future, I will stick with the 95 and older GM 4.3, 5.0 and 5.7.

 

I originally had a '92 4.3, ruined it and put a '94 in, TBI. Since in have a '92 harness and a '94 engine, I don't have the connector for the later EGR, earlier EGR is vacuum. I used the stock harness and computer with no issues, but didn't hook up the check engine light, maybe someday. I find it a little rich smelling, but without the EGR hooked up and no cats that may be why. I always wondered if the cats or EGR would eliminate some of the smell. Once you pare down the original harness there are only about 7 wires to hook up including the fuel pump. I'm using an in tank pump from a Jeep XJ, mounted on the frame rail, it's been there over 2 years. I got the idea from a local guy who has used one before. It doesn't get hot or anything, only issue is that it needs to be primed, I just use a syringe and shoot some gas in it.

Having a harness made and a computer programmed isn't necessary, but it would be convenient, although pricey.

 

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