Can the plenum from an older TPI with cold start injector be used on a '91 SD 350? Can the plenum be modified to block off the cold start injector? I am trying to get ahold of a used TPI system to port match and everything and then just swap with the TPI i have on the car right now because it is my daily driver i dont have the convience of pulling it out and working on it. Most of the systems that i come across are MAF with cold start.

 

Yes, you can use a cold start plenum on your 91, but you would have to use older runners and throttle body as well. Which also implies a different throttle cable.

 

I don't see any reason why you couldn't use the SD throttle body and runners with that plenum... The only difference is the cold start injector passage on the drivers side (which should be covered by the SD runners) and the IAC passage (you can use an SD throttle body on an early plenum, but you can't use an early throttle body on an SD plenum).. The throttle bracket will mount up the same and everything... You'd run into problems if you tried to use a SD plenum on a MAF car...

 

Actually, I think you are correct. The SD runners won't cover the IAC passage on the plenum completely, which would be a problem normally. However, if you use your SD throttle body, it shouldn't matter because the throttle body doesn't use that passage anyway. What I had said about needing a different cable was because the 85-88 throttle bodies engaged the cable differently than the 89-92 throttle bodies. Just ignore that though.

Sorry for the mixup.