Hey guys my 2.8 has been rebuilt and I am waiting for the shop to reinstall it and I want to put a 4.3 tbi on it. Is there a certain year model or vehicle to get it off or will any 4.3tbi work? Also do I need to get the intake manifold bored to match the 4.3?

Yes, the manifold needs to be bored to match. 1st I believe the throttle blades won't open much otherwise. 2nd is there's no since putting the bigger throttle body on without matching the manifold to it because you won't allow more air in otherwise.

Richard <img src="/forums/images/graemlins/patriot.gif" alt="" />

so does it matter where or what model vehicle I get the tbi from or will any 4.3 tbi work?

also do I just tell the machine shop to bore to a 4.3 and they will know the right diameter or do I need to tell them the diameter?

Get you a gasket for the 4.3 and tell them to match the bore to it.

Not sure exactly which 4.3 TBI to get. Search on here and you'll find it. <img src="/forums/images/graemlins/kewl.gif" alt="" />

Richard <img src="/forums/images/graemlins/patriot.gif" alt="" />

A TBI off an early 90's S-10 with a 4.3 would do the trick nicely. There are others that likely will fit too but the S-10 ends up being almost the perfect match, with the exception of the extra vacuum port you need to drill and mods to the throttle linkage.

Note there is a transition year on GM TBI's (somewhere around '92 if I recall) where they changed the style of the TPS plug.

So, if you end up with a later TBI that doesn't have the matching flat TPS plug same as what's on a 2.8 Trooper etc, a couple of choices: snip off the TPS connector from a junkyard wiring harness and splice into your rig's wiring; or change the TPS to the old-style.

Likely the TPS on the old TBI would still be OK and could be swapped over.

As for boring the intake, just go to any auto parts store and tell them you need a TBI base gasket for a '90 S-10 with 4.3.

Here's some good info on the swap:


http://www.4x4wire.com/forums/showf...&o=14&fpart=1#Post928246

http://www.4x4wire.com/forums/showf...&o=14&fpart=1#Post415876

http://www.4x4wire.com/forums/showflat.php?Cat=&Number=445449

Enjoy!............ed