Does The GM 4.3l Have Enough Oomph Up Highway Grades?

The 4.3 can be anything you want it to be really.. Tons of performance goodies for it but even in stock form it was reasonably powerful especially for a little CJ.

 

I would think the 4.3 would be plenty for the JEEP.

As far a V8 goes, I think the extra length is generally at the front end vs. at the firewall/bell housing mounting surface. So, fan clearance and radiators become the issue. Chevy V8's cause a firewall issue only due to the distributor, AFAIK. For this reason alone, I would opt for a little 289 or 302. Not sure where the BOP distributors are, front or back of the engine. May depend on the particular engine.

As far as weight goes, I believe a small block anything is about the same or less than the L head. Not sure how they compare to the 4.3. There was a engine weight table years ago in a Four Wheeler Magazine article. I saved it but, I'm not sure where it's at just now. Might be able google it.

How about an aluminum 215 out of an old Buick or a newer Land rover.

Hard to beat the sound of a V8 in a flattie.

I wouldn't take anything listed below as gospel. There seems to be some discrepancies depending on where you look for weights. Not sure any of it backs up what I remember reading years ago, that a SBC is close to the same as an L head. Maybe I'm thinking a 225 is close to the L4.

Swap Sizing: Engine Dimensions & Tips for Popular Swaps


engine weights

 

I drove a 4 door S10 blazer with a 4.3 and 5 speed 4x4 for a number of years. It seemed have plenty of power to me. Pulling hills I could always get plenty out of it. Just a matter of grabbing a gear or pushing the left pedal further.

 

Yep, something about basic physics. I think the 4.3 would work well. But me being me, there would be a sbc in there. Just puts a bigger grin on my face and I really enjoy putting them together. With a few aluminum parts, you can get the weight close to the 225/4.3 and definitely lighter than the 134's.

 

I do like the sbc / 4.3 swaps . but as said . firewall is a problem with distributor
just need a little work . nothing sounds like V8
got a 4.3 in astro does great till
I am hooked to 4500 lb trailer and have to deal with hills . sounds like it dropped into passing gear . till you make it to top

 

If you go 4.3, do some research. There are several to choose from. Atleast 2 in the TBI era and then more with the Vortec. The TBI versions in the full size pickup trucks offered a few more ponies compared to those mini vans and S10. There is a code to look for to identify the higher horse engines but it escapes me at the moment. It's like a 5 or 10 HP difference as I recall.

 

The YJ should have plenty of room under the hood, and I can't imagine a 4.3 weighing that much less than a small block.

I would be tempted to look for an LS-series V8 in your situation. The aluminum heads will probably make it lighter than the 4.3, and even the least powerful truck version makes in excess of 250hp. The common truck 5.3 makes between 270-295hp

personally I'd hate to make all the effort of a swap and regret not going for the v8 later.

 

I would think a 4.3 would do well but was thinking about the LS motors as well. You could shop around and see whats the best deal available - condition completeness mileage age price etc. before buying any conversion parts.

 

If you do go the LS route don't forget about the 4.8, Just a de-stroked 5.3
IMO the 4.3 would be a big step up from the feeble 2.5

 

Helped a friend put a 4.3 MPI in a formerly 4cyl TJ. He upgraded both axles to Rubicon D44's same 4.10 ratio he had with 4 cyl. Running on 33x12.50x15's. 7 years later he's still able to crest Snoqualmie Pass, 3100 ft at 70 mph in 5th gear. He also went to a Dodge truck 5 speed and Atlas tcase at the same time

 

If I were looking at the Chev 4.3, I would look hard at the Vortec versions. They breathe a bit better. This would be plenty (and then some!) for a little Jeep.
-Donny

 

I love the 4.3L TBI that's in my CJ. Just replaced both injectors. Running so strong right now! My only wish would be for more gears than the 3 I have now. Is your YJ a stick or auto? I'll bet a 4.3L with a 5 speed would be like close to perfection in a balance of power to weight.

 

Had the 4.3 in my Astro. Pulled a larger pop up camper through the Alleganies no problem.