1986 Comanche Engine swap

[signalb]

Hello,

I recently became the proud owner of a 1986 Comanche. After spending some time fixing minor issues such as lights and window cranks, etc. I have decided to swap the anemic 2.8 in favor of something with a little more pizzaz. :chillin: The only question is what engine would be best? I'm leaning towards the 3.4 but am concerned whether that will be enough increase to justify the swap? The other issue is whether to go with a carb set up such as the Webber or Holley 390 cfm or use the 4.3 TBI. Anyone that has already done this swap care to comment? What sort of mpg are you seeing and do you notice a substantial increase in power? I was also kicking around the idea of the 4.0 straight 6, 3.8 buick, possibly the 4.3 gm, or even dropping in a VW 1.9 TDI diesel but keep coming back to the 3.4 for issues of cost, weight (want to keep the truck lighter for off road) and ease of installation (this would be a spare time thing not my day job). Any thoughts?

Except for the engine the truck itself is in very good condition. I'm only the third owner and the only major rust on her is a spot about 3 inches by an inch long in the bed where apparently some dirt had been and caused moisture to get trapped. That will soon be remedied after a trip to the local welder and then Rhino lined.

The only other thing I can't figure out is why my horn doesn't work. I replaced the relay but still nothing, need to do some more digging.

I'll post some pictures of her later. She's currently shoed with a set of 31's so looking pretty good so far.

[JeepcoMJ]

3.4 swap = cost of motor and gaskets to swap, plus custom wiring if you choose to go with the EFI system on the 3.4 (VERY worthwhile IMHO)

 

4.3 swap = custom motor mounts, different trans, different transfercse, new driveshafts, custom wiring (or painless wiring kit), custom exhaust, custom cooling system.

 

 

question is, do you want to blow tons of time and money, or a small amount of money and time?

 

 

I would ditch the 4.3 idea. 4.3's are not very well designed in my experience, and you'd be better off getting the extra 2 cylinders of a 350 for the fact that the mounts and everything are literally identical.

[signalb]

Not really looking to spend lots of time on it, have a 76 Camaro that needs attention also.

 

I see you have an 86 with the 3800 in it. How hard was that and why the 3800 over the 3.4?

[signalb]

As for the 4.3 I've only dealt with three of them. The first I managed to get over 285,000 miles out of before I traded it in, the second refused to die even with a blown head gasket and the third went from a truck to the Camaro, drove it from SC to FL and then got pulled, its latest home was in a Chevy 2500 Cheyenne which I traded even for the Comanche. Guess it just depends on the years, mine where all from 1993 or older. The 2.8 I currently have in the Comanche has a blown rear main seal but going strong (just likes to mark its territory...a lot LOL), starts right up the instant the key is turned. Had a friend that had a 2.8 in an old extended cab S10 that he beat the crap out of but would just keep taking it and asking for more. In my opinion the 2.8's great little motors too, just not very powerful. Funny thing is I'm not really even a Chevy guy, only reason I have the Camaro still is because its getting done up like Bumblebee from the Transformers movie.

[JeepcoMJ]

Not really looking to spend lots of time on it, have a 76 Camaro that needs attention also.

 

I see you have an 86 with the 3800 in it. How hard was that and why the 3800 over the 3.4?

 

 

the 3800 swap is just as hard as the 4.3 swap, but with less viable (strong enough) transmission options.

 

it's in no way shape or form a direct bolt-in like the 3.4 is.

[WBKrazy]

i've owned and driven many vehicles with the 4.3, and both mine and the wife's current DD's have one... mine is a '91 sonoma and hers a '99 blazer.... the older carbed ones and the newer vortec ones are the problem children, but the TBI motors (88 to 92&1/2) are just as reliable as the sbc's of that era... that being said, i still wouldn't swap one into a jeep, because as noted above you might as well go with a 305/350 instead... if you don't really wanna get involved with a drivetrain swap and all you're looking for is a bit more punch, edelbrock makes a bunch of bolt-ons for the 2.8, like headers, intake manifolds, carbs, etc... i had a friend in school that built one up using all the edelbrock stuff and some MSD goodies in an 82 s10 longbed, it wasn't a rocket ship but it was pretty damm quick

[signalb]

Ok so for now I've decided to go with the 3.4 v6 route as a "quick" fix. I may explore the VW 1.9 TDI diesel option down the road but not right now.

 

The next question is, what fuel setup do I use? Holley 390cfm, Carter WCFB <- good for about 400cfm, 4.3 TBI, or something I haven't thought of yet? I'm looking for the best traded off of power and fuel economy as well as ease of setup. I don't mind swapping a harness or two but don't want to sit around with my truck hooked up to a laptop tuning the computer non stop. Any thoughts?

[signalb]

Here are a few pics of the truck so far:

[JeepcoMJ]

Ok so for now I've decided to go with the 3.4 v6 route as a "quick" fix. I may explore the VW 1.9 TDI diesel option down the road but not right now.

 

The next question is, what fuel setup do I use? Holley 390cfm, Carter WCFB <- good for about 400cfm, 4.3 TBI, or something I haven't thought of yet? I'm looking for the best traded off of power and fuel economy as well as ease of setup. I don't mind swapping a harness or two but don't want to sit around with my truck hooked up to a laptop tuning the computer non stop. Any thoughts?

 

 

use the camaro/firebird wiring. piggyback your factory harness. easy as pie.

 

 

get an inline fuel pump that puts out enough PSI and splice it into your fuel lines.

 

 

it's easy, and you won't need to tune it with a computer so long as you "trick" the 3.4l into thinking it's still in a camaro/firebird by putting all the proper up and downstreem 02 sensors back in.

 

 

carbs SUCK for mileage and performance.

[husky410ohio]

I am swaping in a 350 chevy with a SM465 trans an NP231 in my 1988 MJ

https://cid-acd8ecd25256a1fa.skydrive.live.com/self.aspx/New%20album/HPIM0742.JPG

[signalb]

Has anybody used or looked into this:

http://www.gotpropane.com/p1.html

 

It has me thinking about going with a duel fuel setup and using an Autolite 2100 carb or Holley 390 for the gasoline portion.

The range would be ridiculous with 23.5 gallons of gasoline and 8 gallons of propane going through that little 3.4 v6 engine.

Plus propane is cheap around my area so for in-town driving I could use that exclusively and $ave wampum. :cheers:

[Maryland MJ]

I have the exact same truck as you do--same engine/same tranny--I even have the same color! Anyhow, if I don't end up selling my Comanche, I was looking into this. I used a lot of stuff from Novak for my engine/tranny/t-case swap in my 95 Wrangler (5.3 Liter Vortec/4L60E/NP241) and have been very happy with it. They are very knowledgeable and happy to help. Check this link out:

 

http://www.novak-adapt.com/knowledge/xj_swap.htm

[JeepcoMJ]

I have the exact same truck as you do--same engine/same tranny--I even have the same color! Anyhow, if I don't end up selling my Comanche, I was looking into this. I used a lot of stuff from Novak for my engine/tranny/t-case swap in my 95 Wrangler (5.3 Liter Vortec/4L60E/NP241) and have been very happy with it. They are very knowledgeable and happy to help. Check this link out:

 

http://www.novak-adapt.com/knowledge/xj_swap.htm

 

 

you forgot to mention EXPENSIVE.