Chevy 4.3L V6 in a 40??

[lunyou]

Okay guys I'm back. I have a question. I have found a 40 that has had a 4.3L V6 transplanted in, the owner calls it "a chopped off 350".

He said it runs really nice and "will climb a tree".

So is this a good swap? Any known problems?

lunyou

 

[bigndn]

Might start by reading this....

https://forum.ih8mud.com/40-55-series-tech/210001-chev-4-3-vortec-my-fj40-advice.html

 

[fireflyr]

A friend has a 4.3L in a '80 cj5 and it doesn't get any better mileage than my F engine. It is a hell of a lot more driveable, and does well with the stock 4 speed but he averages about 14 mpg. The power is nice though and it's a really short engine so there's alot of room.

 

[bikersmurf]

the 4.3 is 3/4 of a 350.

As with any other V8 swap check how it is adapted to the transmission... Custom bell housing are best adaptor plates work if well made.

I've also seen a lot of motor mounts and transmission mounts that I wouldn't touch with a ten foot pole.
Then there is wiring.....

 

[Brian in Oregon]

A friend has a 4.3L in a '80 cj5 and it doesn't get any better mileage than my F engine. It is a hell of a lot more driveable, and does well with the stock 4 speed but he averages about 14 mpg. The power is nice though and it's a really short engine so there's alot of room.

The best either of my Chevy AWD Astro vans with the 4.3L V-6 with tools and equipment have gotten was 15 city and 18 highway.

If you do the math, a 350 gets about 10 to 12 mpg in an FJ40. Since the 4.3L is about 3/4's of a 350, you'd expect it to get proportionally better gas mileage. If you multiply the typical 350 mileage by 25%, you get 12.5 to 15. So 14 mpg is in the ballpark.

I'm amazed how my power the 4.3L has for what it is, at least in the vans. I have no clue how it would be in an FJ40. But as far as fuel economy goes, I don't think it gives enough of an increase to make it worthwhile. I'd rather look at a 6.2 or 6.5 diesel.

I've heard of pretty good longevity claims for the 4.3L, but I was disappointed with my first one. It went 70K, then started overheating and losing water. Apparently a head gasket went, and dumped the coolant into the oil pan. The motor still ran, but it had to be replaced. I hope that was just an aberration.

 

[Downey]

I was impressed with how well my brother-in-laws full sized Chevy Pickup with 4.3 pulled his 22 ft. boat. I was not impressed with how my 18 ft ski boat with 4.3 would not pull two skiers out of the water. While I agree I would rather have a 200 h.p. 4.3 than an 800 lb. / 120 h.p. 6 cyl., I would much rather have the big cubic inches of the Chevy V8 ( big cubes don't have to work hard, and don't take much throttle to work hard).

 

[Brian in Oregon]

I was impressed with how well my brother-in-laws full sized Chevy Pickup with 4.3 pulled his 22 ft. boat. I was not impressed with how my 18 ft ski boat with 4.3 would not pull two skiers out of the water. While I agree I would rather have a 200 h.p. 4.3 than an 800 lb. / 120 h.p. 6 cyl., I would much rather have the big cubic inches of the Chevy V8 ( big cubes don't have to work hard, and don't take much throttle to work hard).

Translation: When it comes to power, there is no replacement for displacement.

 

[fyresq]

The 4.3 may have better mileage than mention above if it is a TBI or Vortec EFI. Do you know what year the motor is?