I'm restoring an 87 Iroc and someone polished the runners and plenum. Are there any casting codes on these parts? From the information I've located I still don't have a clue. The manifold was not touched so I will be able to keep that. I just bought a complete TPI setup off of an 89 Formula 350. I don't have it yet and I haven't torn my engine apart yet to look, and since I know someone on here has the answer I thought I'd ask. Thank you.

 

You are going to have a problem if you use the 89 intake base. It does not have the hole that your cold start injector mounts into. The 89 driver runner does not have the hole either, as the injector goes though the runner, and into the base. The 89 plenum does not have the air bypass passage that feeds air down through the runner and into the base. As a result if you use any of the 89 stuff you must use it as a complete set, and have a custom PROM burned using the 89 bin file with VATS shut off.

 

Thanks for the reply. If I get a setup from an 88 would that work for what I need (runners & plenum). I know someone that gets these in once in a while and I'm sure he would trade me when/ if he gets one. I plan to use the 87 base, since I'm certain that has numbers/ casting date.

 

Yeah you'd be fine with an 88 setup.

 

Thanks for the info. There aren't any casting/ date codes that would prevent me from having the incorrect piece on my car then?

 

85-86 TPI are the same
87-88 TPI are the same
89 is one year only
90-92 TPI is the same, however some 92's used blank throttle body plates, and corvette runners to use up the remaining stock after the C4 switched to the LT1.

Most people not well versed in the variations of the TPI from year to year/corvette to fbody will never know if you put a 92 setup on a 85 or any other combination. There aren't really any casting marks, but I'm pretty sure there are foundry marks that might contain a date code. At any rate I'd suggest staying with the same years to avoid compatibility problems anyway.