4.3 v6 change over?

[Nightrider]

Has anyone made the change over to the newer 4.3.? I'm puttin a 71 burb back on the road, and I have a complete 96,4.3 with the 5 spd and was wonder how well it would work. Damn gas prices killing me!

[Super Duck]

I think the 4.3 would get worse milage because the motor doesnt put out enough power for a 6500lb truck. other than that the swap should be strait forward. the 4.3 is a 350 with two cylinders lopped off. if I am not mistaken the motor mounts are in the same spot.

[arkracing]

What duck said is true about the motor fitting. I'm not sure about the 96 model year..you should be able to tell just by looking at the motor mount pads..if them look like the small block then they will go.

you might be ok with the 5 speed but I would have to agree that the 4.3 might be worse on fuel than a SBC in that truck....i've had s-10's with 4.3s that got worse milage than a big truck

my 97 4x4 s-10 only averaged around 15 on the highway and that was with the 5speed.

so with the bigger truck your gonna be in the gas more to get it going and you won't have any power on hills etc, etc

[bigunde]

Are yall sure about that motor mount deal?My 90 chevy 1500 v-6 had a adapter plate because the 4.3 was set back a little further.I have looked at several 88-98 trucks and thay all have it.I had to cut that plate away to intall the mounts for the v-8

[Tx Firefighter]

Mine too. I've converted V6 trucks to 350s. The engine mounts on the V6 were several inches rearward of the V8 spot. I had to cut the adapter brackets off the frame so the new V8 mounts would bolt in.

I'd say they were 3 or 4 inches rearward of V8 mounts.

[bigunde]

hey fireman,isnt it fun trying to get the nuts and bolts for the mounts on when bolting them to the frame.

[Tx Firefighter]

I seem to remember using a universal socket, an extension, a universal, and another extension.

[Nightrider]

well, I knew a old basterd who raced in the monster truck thing,he told me he used those 4.3's in all kinds of daily drivers. Slow pulling off the line but , if your driving down the hwy at a constant speed 90% time , does'nt it get better milage than the 350?

[Longhorn Man]

The 4.3 is kinda funny as far as motor mounts. I had looked at slapping a 307 into our old 4.3 S-10 blazer when the 3rd fuel injector /regulator/hose assembly ect went bad. At 300 + bucks each tiume, it gets old REAL quick. Plus there was the 4 or 5 $100+ EGR valves...remove and clean every 6 months, and they still get clogged full of garbage.
As far as MPG, in an overdrive equipped, lightweight S-10 Blazer, the best MPG we ever saw, with the cruise control set at 70-ish, was something in the neighborhood of 19 MPG. Pathetic IMO for what it was.
Anyways, I agree it would be a bad Idea to swap it in...however...to answer your question...it all depends on what 4.3 you want to install. (DON'T get an early 90's CPI engine...W code on the VIN)
On any fuel injected swap, you'll need the complete harness. Since there is probably no aftermarket stand alone harness...you'll end up with a whole bunch of crap you don't need for your use...but you'll need it for the computer to work right. you'll need a high pressure fuel pump...real high pressure if you want the CPI motor. There will need to be a return line installed, Map sensor, O2 sensor in the exhaust, catilitic converter....EVERYTHING from the donor vahicls. You'll need to wire the check engine light visible from teh drivers seat, you'll have to adress the electronic speedo verses mechanical speedo....all kinds of fun stuff.
And the kicker is, since they do emissions tests in your area, if you follow the letter of the (federal) law, your '71 will now be clasified as what ever year the engine is. So it'll have to pass 90's smog standards.

[Yellow Cheyenne]

I have a 1/2 ton 2 wheel drive ext cab chevy Silverado pickup with the 4.3L and 3.42 rear end and a 4 wheel drive Suburban with the 5.7L with 3.73 rear end. Both are 96 models and have the 4L60E transmissions. The pickup will get 19-20 mpg at 70-75 MPH and the burb only gets 15-16 MPG (not a real fair comparison as the burb is heavier and 4x4). I would say the 4.3 has enough power to get me around and I am satisfied with it cause I bought it with gas mileage in mind. The 96 motors are Vortecs and are rated at about 200 HP from the factory, as opposed the my '72 with a 350 that is only rated at about 175 HP (and gets about 10-12 MPG on the highway). Means you already have the engine and transmision, go ahead and use it. If it doesn't work out, it shouldn't be too hard to convert to a 350 at your convenience. Just my .02.

Randy

[44th Miss Inf]

I have a 96, full size GMC extended cab SLE, with a 4.3 5speed, with 3.42 gears that I brought brand new. I have ALWAYS gotten over 22 miles to the gallon not towing. Truck has 215,6xx miles as of tonight, and I finally had to put a water pump on it. About a year ago, the fuel pump went out.
I have had my 67 Camaro on a trailer and pulled it at 75 mph in 5th gear, and got 19-20 mpg. While not the fastest on takeoff loaded, it does OK.

Virgil

[Longhorn Man]

Hmmm, we went through 5 fuel pumps in less than 5 years on ours...and the tank was NEVER less than 1/4 full.
Anyone ever dropped a first gen S-10 blazer tank? NOT fun.