I'm going to be running an 86 plenium on my 89 IROC with the 89 tb, I noticed the 86 plenium have what I think are IAC passages in the front of it where the 89 doesnt.. Will this cause me problems? If so can I simply block the passage off? If so how would you recommend blocking it off?

 

Is it 86 motor ?
There are two different TBI"s There the same expect for the linkage plate.

If you have a 88+ motor i don't think that the intake manifold will line up correctly with the heads and block.

 

I have both tb's, the 89 TB has differences in the IAC passages if you look at them from behind, it's a little different than the 86 version, and yes the 89 has a progressive throttle linkage. It's not an 86 engine, though even if it were it wouldn't make a difference. The differences between the 2 base manifolds is with the angle of the center 4 bolt holes, either intake will both up to either style head provided you elongate the holes properly with a drill. The block makes no difference, just the heads.

Anyone know if I will encounter problems if I don't block off the passage in the plenium?

 

Are you doing this on the stock manifold ?

 

I'm using the factory 89 base, although I have both, as stated before both bases are the same except for the center 4 bolt hole angles.. Nobody knows if I'll run into problems? Guess I'll just bolt it togather and see what happens.. If it doesn't work I'll go back and change it.

 

Im just trying to figure out what you are doing or talking about. I know about longating the holes, but the only IAC thats ringing a bell is in your TB.

If you can snap a pic or enlighten me some more maybe I can help

 

camera's broken unfortuently, I'll see if I can find any pictures around here. Basically the 86 plenium have IAC passages which continue into the plenium, its a small triangle shaped hole that matches up to the one in the bottom of the tb, the 89 plenium doesn't have that, its simply flat on the front with 2 holes for the tb. The backs of the tb's are also different, I'll see if I can borrow a camera and take some pic's.. I was just hoping someone around here had already gone through something like this.. there no reason blocking off the port in the plenium shouldn't work so if it does prove to be a problem I'll just block it off and call it a day..