Ed Mc. wrote:Tim, looks like the injectors are physically different, too, and would not interchange. So that kinda messes things up!
Are the intake ports of the newer head different than the older?
That is correct, the injectors are different and the ports they mount into on the intake manifold are a different size than the older 2BBL intake. Not sure if the newer injectors have a higher flow rate, but I know they have three ports in the nozzle with a definitive spray pattern, and no exposed pintle, like the older injectors have. They are not interchangeable, but the upper plenum is easily swappable, so the benefit of higher air flow can be realized using the 1BBL throttle body, but retaining the older lower plenum. It's a great combination, with relatively little effort. I'll try to get some pics up comparing the two in good lighting.
On a related note, there are two distinct versions of the 1BBL throttle body, with the smaller one being the CAL version with electric EGR, which is why I advised against it. The camshaft, however, from that version is the improved, later design, and provides a bit of extra torque, so it can be easily swapped into the earlier engines with no trouble.
Unfortunately, even the 1BBL throttle bodies mount differently to the upper plenum, so they are not interchangeable, either. I have had both versions here at one time or another, and mistakenly purchased an engine with the electric EGR and smaller throttle body early on, so it's been sitting on a shelf taking up room for quite some time now. I get the feeling it seems to be GM's misguided attempt at redesigning the four-cylinder intake to use their parts (MAP, rather than MAF, for instance) and really didn't improve on the overall design whatsoever, as compared to the true Isuzu-developed 1BBL intake, which utilized the simple vacuum EGR and no GM parts, and backwards-compatible lower plenum which uses the smaller injector ports.
The CAL version really is a separate entity, as far as the intake is concerned, and doesn't provide much for modification purposes, unless someone knows of a vacuum-operated EGR which will fit the electric EGR port, in which case, this intake might actually become usable after all. The rest of the engine, however, is very much worth having, since it has smaller combustion chambers and pistons to match, and improved camshaft.
Ed Mc. wrote:... That would lead me to believe you could bolt the later upper intake and the earlier lower intake to the '94 head and use in in an early 2.6.
That's exactly what I did with the one I modified. Newer upper plenum, older lower plenum, older throttle cable bracket shaped to fit, EGR port tapped and threaded on the upper plenum, and 1BBL throttle body with intake piping and MAF.
How to rebuild a 2.6L 4ZE1 distributor
'89 S Trooper - "Kal-El" - 4ZE1
'88 LS Trooper - "Delta" - 4ZE1
'92 Pickup - "Blacktail" - 4ZE1
'89 S Trooper - "Red Leader" - 4ZE1
'89 SE Trooper - "Vader" - 4ZE1'90 Trooper - "Leia" - 4JG2T swap on hold
'89 Pickup - "Wicket" - 4ZD1
'90 S Trooper - "Nan" - 4ZE1 (possible V8 swap - Ford 302 with 5 speed?)
'94 S Amigo - "Artoo" - 4ZE1, SOLD
'92 XS Rodeo - "Jabba", LH0, 3.1L V6
'89 S Trooper - "Chewie" - 4ZE1, TRADED
'89 XS Trooper - "Red" - 4ZE1, SOLD, bought it back'89 LS Trooper - "Obi-Wan" - LH0, 3.1L V6
'88 S Trooper - "Stormtrooper" - 4ZE1, SOLD
'91 S Trooper - "Ghost" - L32, 3.4L V6, SOLD
'89 S Trooper - "Angry Bird" - 4ZE1, SOLD
'89 S Trooper - "Phantom" - 4ZE1, salvaged
'90 Pickup - "Uno" - 4ZD1, SOLD