I found a spare intake manifold for my 2.8, which I plan to have bored out to match a 4.3 throttle body, which got me back to looking for that same TB.

I found one on eBay (didn't get it, but that's beside the point here), which was listed as an application for 4.3, 5.0 and 5.7 engines. I don't consider eBay seller descriptions as particularly reliable technical information ( <img src="/forums/images/graemlins/lol.gif" alt="" />), but it did intrigue me enough to do a little more research.

In the Summit Racing catalog section for the Holley hi-po GM TB's, the 2.8 replacement is listed at 400 CFM, the 4.3, 5.0 and 5.7 replacements are all listed as 670 CFM. Hmmm...

Searching Google for GM injector flow rates, brought up a Megasquirt installation page, which listed the GM injectors and TB's. The 2.8 is listed as a 35MM bore with a 33 lb/hr flow rate injector and the 4.3, 5.0 and 5.7's are all listed as a 43MM bore, but with 40, 45 and 55 lb/hr injectors respectively. Double Hmmm...

It obviously needs more checking (including some junkyard side-by-side comparisons), but at least preliminarily, it appears that all of the 90* small block engine TBI bodies could be used for an upgrade to the 60* engine family with the appropriate injector sizing...

So, it's possible we may have some more potential donors for TB upgrades! Anyone heading for a junkyard soon that could see how the 4.3/5.0/5.7 TB's compare in person?

Jay