Well, I have a 91 1500 with a "Vortec" 4.3. I know that over the years they have improved this engine, until it put out about 200 hp in 96. I have the 160 horse version in my truck. What I wanted to know is, Could I swap a complete top end from a 96+ 4.3 and retain the same block and bottom end? I haven't heard of anybody doing this, and I could probably figure out if it works if i had all the parts in front of me. I know I would most likely have to swap fuel injection, intake manifold, ECM, and what not. I just was wondering if anybody has information, or knows why this won't work?

 

Intake manifold bolt pattern and orientation is different.

 

I'm not trying to doubt you or anything, but if i used the proper intake from a 96+ 4.3 would it work? I'm wondering if I use all the sensors to provide signal to the same ecm from that 96+ motor. I guess I should have said, are the basic short blocks the same? Even though I know the newer ones had balance shafts

 

Basically yes, they are. My concerns would then be in the crank position sensor location and reluctor ring as well as the knock sensors... Swapping over of the electronics is the hard part and is MUCH easier said than done. You'll have to adapt to the rest of the vehicle, add O2 sensors...

 

I guess I'd be better off swapping a whole motor+harness+ecm huh lol thanks for your help, I've always wondered about the heads. Since they should be similar externally, i'd imagine it would be a direct swap. BTW I've followed some threads on here, but I'm pretty much new to this forum but I've grown up with blazers my whole life, my parents always owned two at a time. We actually had a 91 s10, the 91 full size I have now, and an 01 at the same time. I just want to say this site is pretty sweet, its cool to be talking directly to the admin, good job keeping the site going

 

For your truck, I would highly recommend a 350 swap as you can just swap the EPROM.

If you decide to go that route, you'd need to find an early '90s fullsize with a 350 TBI motor. The accessories on the front of your motor would bolt up to the 350. Your wiring harness may work, but to be sure, you could just grab a full engine harness from a fullsize either through eBay or a local Pick-n-Pull yard.

If you want to stick with the 4.3L, there are things that can be done to increase the performance of the motor. You can get a set of headers, custom exhaust, high flow catalytic converter, a new cam, higher ratio rockers, do some head work to increase the flow, and get the EPROM programmed to take full advantage. With all of these combined, you should be able to boost the horsepower over 200, but it isn't going to be cheap.

And thanks for the kudos! It really makes it all worth while when someone takes the time for a thank you or praise such as you have done!!

 

I have been thinking about the v8 swap, but I haven't figured out what I want yet. I have done a few things with the truck, I added a TB spacer, I recently did a valve job since I had access to a cutting machine in school and I had to do the valve guide seals anyway, and I smoothed out the ports a bit, but I wouldn't call it a porting job. I also have a cat back dual exhaust. I did get some power, but its still not quite what I want, even though it does do pretty good for what it is.

What I want kindof contradicts itself. I want: good power, nice torque, reliability, fuel economy, to pass inspection with flying colors, and not compromise any of the items I want. I'm sort of afraid that if I pull up to a nj inspection station, and they pop the hood and see 8 spark plugs theyll fail me. This is why I've held back with my truck