The Stovebolt Site Forums The Shop Area The HiPo Shop 1984 I-6 to V-6 conversion

My 12yo grandson was gifted his Maternal Grandfather’s 1984 Chevy 1/2 ton. It has the 250 I-6 with every smog device known to man. Miles of vacuum tubing, pumps and wiring. It has not run in many years and he has no intention of trying to make it run. It has the 4 speed on the floor.
His Maternal Uncle gave him a running V-6 out of a early S10 and he and my son Terry B (truck in the original gallery) intend to remove the I-6 and replace it with the V-6. I have no experience in the later engines at all.
My question is: What exactly are they up against as far as a direct bolt in, plug and play swap? Motor mounts, bell housing, clutch and pressure plate swap without modifications? Will the original transmission work? If it were up to me I would install a SBC and call it good but it’s not up to me. So school me on the process. Thanks

If it is a 4.3 V6 it is a simple swap as bell housing is the same as are the motor mounts, stands will need moved. Chevy didn't go to throttle body till 1986 so get a carb for the V6 and it's an easy swap. NOT so if it is a 60* V6. Used to do a lot when the lousy integrated I6 heads would crack. If it is a 4.3 with an automatic the trans will be a 700R4 overdrive so don't let it go cheap.

"An early S-10"- - - - -the first few of them had a 2.8 liter V6 with an oddball carburetor and a distributor with a vacuum advance. That one would be a nightmare to swap, as the bellhousing bolt pattern and a lot of other stuff won't be compatible with the running gear mated to the 250 I6. A 4.3 with a carburetor would be a lot simpler. If the throttle body fuel injection is involved, the electronics are going to get pretty hairy because of all the sensors needed, the computer, and the fuel tank mounted high pressure fuel pump. Mercruiser made a 4 barrel intake for a 4.3 that ran a Quadrajet, and a non-computerized HEI distributor with only centrifugal advance, I believe.
Jerry

If the 250 is in the truck and loose it could be a pretty good runner. I just removed all the smog stuff on the 292 in the 65 I bought from Don King last Stovebolt reunion. I removed the Octopus of little lines that go in the top of the head and plugged them all with Brass plugs, Plugged up the rest of the smog stuff on the engine and rebuilt the carb and it's a strong runner.
Like other's said if the S truck V6 is a 4.3 it's basically the same as installing a small block just minus 2 cylinders. If the V6 is the smaller one's he'd be better off keeping the 250. And the stock 4 speed in the truck should bolt right up the a 4.3.
Mongo

The engine is a 4.3 from a 1991 S10. The S10 owner is heavy into Autocross and is putting a LS in the S10 thus the availability of the 4.3. The computer and all the wiring come with the engine.

I's reccomend losing the TBI injection and the electronic spark advance distributor, and put a carburetor and a vacuum advance HEI on it.

https://www.ebay.com/itm/165522595172?

https://www.ebay.com/itm/164612799479?

Jerry

Thank you so much for the advice. We are going to do a full casket replacement on the motor before it goes in as it was leaking a little oil. The motor runs strong and sounded great before it was pulled last week. We even have the 4L60E transmission that was in the S10. Really would like to keep it a manual for now, so it is good to hear the bell housings are the same. Will have to purchase new motor mounts as the one on the 4.3 had fully gone past the expiration date. The rubber fell out as we lifted it out of the frame. Any advise will be gladly accepted. As Justhorsenround said would love to just drop a SBC into it but can't beat getting a free running motor.

Here is a pic of his truck we will be building up. All of the trash from the back has now been removed and the truck has been transported to our home so we can work on it here together.

Yep- - - -trash the electronics and make it a "dumb" engine. The I6 flywheel and clutch should bolt right on, I believe. I don't remember if the 4.3 is an internally balanced engine or not, but I believe it is. Check the harmonic balancer and the transmission flex plate to see if there's any kind of offset balance weights.

OK- - - -just did a little research- - - -the same flywheel that fits a 250 I6 also bolts onto a 4.3- - - -and a bunch of small block V8's- - -305, 350, etc. Just swap the standard shift parts onto the 4.3 and bolt it in.
https://www.ebay.com/itm/265226751995?

Jerry

I'd leave the mattresses. It's a bed, isn't it??

John, we know where that mattress has been.

This sounds like an interesting build. Something a little different.

John

I will try to keep y’all updated as it progresses. With 4 kids under 12 Terry B has limited time to spend on a truck that doesn’t need to be done for 4 more years.

Not that I want to confuse you, but a couple of different ways to look at your "problem":
First, the 250 L6 is a very good engine, reliable, which can be improved, either just aesthetically (aftermarket intake/header, valve covers...) or performance-wise (camshaft, carbs...). The 250 can easily be just as pleasant to use as a mild small block. I would thing that removing the emission stuff is easier than swapping in a V6, even if you need to ask a few questions in a forum.
The TBI injection system (with its dedicated distributor) is an excellent system, dead reliable: keep it! Simple, it will last for ever and will run really smooth (smoother than a carb).

The 250 will require a total rebuild. Funds are not available for that and the 4.3 was free. Thank you for your concern about my “problem”.