4.3 v6 in 1st gen?

I'm new here, this is my first post. I have a 66 GMC van. It currently has a 327 sbc in it that needs a rebuild, I really love the power and rumble of the v8, but with the price of gasoline I'm contemplating putting a 4.3 v6 in it for better fuel economy. Has anyone here ever done this? I don't see why it wouldn't work, I'm guessing I may have to fab some engine mounts. Anyone else here have ideas on anything else it may require?? I'm still running the factory 3 speed trans too. Thanks for your input.

I know that the 4.3 has the same bolt pattern as the 327 and the motor
mount pads on the blocks are the same bolt pattern also, just have to
move the engine crossmember back in the frame where the v6 wants it
to be, not really that tough. the threaded inserts will be the hardest part

If you want better fuel economy you best think about a trans with your V6.

A 4.3 with a 700R4 and the correct rear gear to match might be a wiser choice.

M1D

If you go with a 700r4, or any other transmission that doesn't hang from the original mount, you will have to put in a different transmission hanger anyway. Maybe you wont have to move the engine mount.

Welcome to the site!!!

i would think you should only have re locate the raditor and shroud. your only missing off the frount of the motor the back is same as v8 small block.you could go back a few years and find a 231 v6 like they ran in the chevy malbu i rebult one of those years ago punched it 40 over and still got over 20 miles per gal. on hwy,

Just a suggestion, that my Dad told me back when I had my 53 ford...pop the indent out from under the gas pedal and put 2 extra layers of carpet under it, and my fuel economy would greatly improve...lol..jk.

the 4.3 is 4.400 inches shorter than the small block chevy
the 700r4 is just a little over 3.00 inches longer than the three speed auto or
th 350. so if you do the math and you put the 4.3 on the original van crossmember and bolt the 700r4 behind it i think you can use the stock
driveshaft, just have to fab your own tranny mount but not that tough.
I know I will be finding out for sure on this setup, this is the way i`m
going.

The motor mounts for the 4.3 and the 327 are in the same spot. When chevy made the 4.3 all they did way cut the first two cylinders off. If your using the 3 speed the 4.3 will bolt right in. You will have 4 more inches between the block and the radiator.

another question will a 4.3 fit in a stock 1th gen dog house??

The 4.3 is the same width as your 327.


m1d

yea even at you still jumping through hoops to make a v6 fit. so with that said me my self i would go with a v8 but thats me. the v6 is still a choice.

If you have a properly running 4.3V6 and a properly running 327 with all elses the same. same FI system same trans and all. I do not belive the v6 would get a measurable amout better gas milage. Because it comes down to the science of one gallon of gas produses a fixed amount of heat energy when burned "eficiently". It takes a fixed amount of energy to move a specific weight at any given speed. Those laws are as constant at gravity. If you want to drive around in a 1/2 ton van, it takes X amount of fuel at the best of times and you can't change that.

The key to best posible gas milage is in effecientcy of the Machine and the driver.
I can easily agree that a fuel injected and computer controled engine will get way better fuel economy that any engine with a toilet bowl flushing thermoboge carberetor all day long.
The other reality is often, with too small an engine, the driver is always putting his foot into it to try to get going forcing that poor engine to always run way outside its most eficient range.
More often then not, the same vehicle with a larger engine gets the same or better gas milege because you hardly have to press on the gas to keep with the flow of trafic. Mind you there is a limit to "larger"
Thats just the bigger VS smaller engine thing.
Like I said earlier the other biggest part of the fuel economy formula is the efficiency of the machine itself.
I can tell you from expirience that I have never seen any engines efficientcy be driveway improved over and above what the Factory spent millions on reseach and development for production.
If fuel economy is your concern then select an modern engine, trans and rear gear combo that was designed to be together and is the right size for the wieght of your van and tune it all to exact factory specs including all its designed emision contraols as it was designed to run at and use the right fuel it was designed to run on. That will be your "best fuel economy" approach.
Any other home made engine/ drive train build up you create will not be as efficient as a foctory set up. I garrantee it, If you think other wise then bring your set up to a dyno test facility and you will likely be suprised to dicover its not producing the HP you thought ,and its probobly using way more fuel then it should be. This is what most every hot rodder finds out if they actually bring there machine to a dyno test. This I know from 45 plus years of hot rod vehicle involvment both personal and profesionaly as well as doing tune up and engine managment on a profesional scale for 15 + years.

M1D

I've owned a couple of later model vans, one with the dreaded, carbed 305 V-8 and one with a fuel injected V-6. The V-6 got at least 5mpg better even when pushed. Of course that might be more about induction than displacement. Personally, if you have a wide v-8 doghouse already, a v6 sounds like a great idea and it should give you plenty of room to do work on the front of the engine. That extra room is great when changing belts and such. Good luck, Mark

I have a 4.3 V6 and a 700r4 in my Sportvan 108. The driveshaft is stock and the radiator is mounted in the same spot. Engine mounts are in the same place. The only thing thats different about the mounts is that the hole in the middle had to be re-drilled farther back, if I remember correctly. I could probably climb under it and shoot a picture if your interested.

So far I have gotten around 17mpg but my engine isnt stock and the kinks havent been worked out yet. Im pretty sure I need a chip re-burn because something definetly isnt quite right about the fuel management. Hopefully once that stuff is fixed I will be seeing closer to 20 or better...

20 isn't too far out since my '92 with a V6 was a fully dressed leisure van and had to be heavier and got better on a tailwind. Aerodynmics may have been a wee bit better than the flat windshield. Also, I think the V6 was a solid high RPM engine tho the straight 6 should out torgue a V. I'd go for a V6 if a lot of highway as you shouldn't need the V8 in such a light vehicle.