69Boss302

My brother has an S-10 with the motor on it's way out. Last week, a spark plug came apart and consequently bent a valve. He pulled the head, had it fixed and put it all back together. However, it seems that more damage may have been done than originally thought because it still continues to knock.

So, I am taking it upon myself to learn as much as possible about these motors. My thinking is that at this time, it might be easier and cheaper to swap in a newer, lower mileage engine. I found this on Wiki,

"4300 applications:

1985-2005 Chevrolet Astro/GMC Safari
1991-1993 GMC Syclone/GMC Typhoon (See LB4 below)
1988-1995 Chevrolet Blazer/GMC Jimmy
2001-2002 Chevrolet Express/GMC Savana
1988-2003 Chevrolet S-10/GMC S-15
1994-2001 Oldsmobile Bravada
1985-2001 Chevrolet C/K "


Will any 4.3l from any of these applications swap into his 94 with little to no problems? Except the SyTy's, of course.

Which applications will be the best donor?

What are things to watch out for?

I know that timing covers, cams and such changed throughout the years. Aside from that, I know little else yet.

Thanks.

EDIT: What are the differnces between VIN "W" and VIN "X"?

Revolutionary

iTrader: (6)

Is it a safe bet that is a TBI engine??

I know a big group of the 94's had the TBI

If you wanted to go to a 96 and up style you would have to make harness changes due to the variations in fuel injection systems as well as a pump and line mods.
Whats the overall goal?

69Boss302

His is the CPI motor.

Will the blocks themselves be the same throughout the years? If they are, then we could just swap over all the acc and drop it back in.

EDIT: The overall goal is to replace the motor in his truck. No performance mods needed.

Revolutionary

iTrader: (6)

The vortec heads are different all together. The blocks are not quite the same the 95-up mpfi blocks are a balance shaft and use a 1 piece rear main. So if it's a stick the pilot bearing is different.

The accessories will physically bolt up the intake most definitely will not. If you use the injection off the newer donor truck you have to remember there is a pretty significant wiring difference as well as fuel lines. The best way to do it would be just get a reman or rebuild what you have if you don't want to do any major modifications with wiring programming or fuel.

Either that or get a whole harness and motor from newer truck.. they are on ebay all the time as well as other places. And swap it all in at once. That would be my opinion

69Boss302

Let me make sure I understand this correctly.

If we were to use a newer VIN "W" motor, say from a 99 Silverado for example, then everything from the donor truck would need to be swapped over to his S-10?

So, in fact, no other 4.3L VIN "W" engines can be used except for the same year and model that came out of a similar truck.

I'm approaching this with the same logic as doing an LQ4 swap in my truck or a 3.0 swap in my cars. Which is essentially, remove old motor, unbolt everything, bolt everything to new motor and put the new engine back in.

Revolutionary

iTrader: (6)

Yeah.. you have a CPI headed motor.. that intake and head combo is different from everything from 95 on. They killed that engine because the inferior design of the intake and runner combo amongst other things. the W in the Vin doesn't signify what kind of EFI it has. Especially on a newer truck calling it a W just means it's a 4.3.

There are tremendous differences between the "vortec" 4.3 heads and the heads before it. The motor you have is essentially the same one used in the typhoons just with a few changes obviously the intake.. BUT it's a non balance shaft engine. Which I would bet dollars to doughnuts it also has a Chip based prom.

The intake itself on that style engine has one huge fuel injector that sprays though 6 seperate nozzles. Versus the newer style that say you find in a 99 s10 that has one common runner with 6 poppets and hoses. They are controlled totally differently. You have 2 wires going in yours versus the 6 going in that intake. Also The angle of the intake versus the head is diffrent. I belive a few degrees. The syclone guys that prefer the better flowing vortec heads end up welding up the syclone intake adding material to it then re machining it to mate to the new style heads. It's a rather involved process.

So approaching it from where you are. Your easiest choice is to get a reman long block or reman what you have. Or again Like I said if you are set on going to the newer engine buy one complete with a harness and computer and get your foot in the door that way

69Boss302

That certainly does clear it up, thank you.

one last question.
Keeping my options open, if we were to swap in a newer motor, will it bolt up to the existing automatic in his truck? Not sure what kind it is or if there were any options that year.
Do you know of any changes to the block? Would we need to swap the trans as well or just the bellhousing. Assuming that particular trans has a removeable bellhousing.

Revolutionary

iTrader: (6)

The trans will be the same essentially. There are a couple differences. Mainly internal. If it is a manual trans truck the pilot bearing might be different only because I know the cranks are different. The automatic should fit exactly the same. The only differences you will see are going to be in how the trans lines are routed.

69Boss302

ok, one more last question.

Are the 94/95 CPI and TBI motors interchangeable? Or are there differences aside from the intakes?

Revolutionary

iTrader: (6)

Different heads also. The CPI had a slightly different setup. I believe it has no center most intake bolts and the TBI's do. The wiring is quite different on the actual injection setups as well.