To convert a 1989 TBI car to 1986 TPI do I need to install a 1987 lower TPI intake manifold to match up to the heads? I have a 1986 doner car with everything else.

 

Yes you will need a newer manifold for your center bolt heads. You can use the older one but you will need to do some work on the center bolt holes in the manifold because they will not line up with yje head properly. Some guys use large washers to compenstate for the hole angles but it is best to redrill and tap the holes to match better. Using the old one is much cheaper.

 

Thanks, I see from the many emails I have received on this topic that it may be best to use a TPI set up from an '88 or '89 because there are subtle but important differences. i.e; wire harness, serp (alt A/C different), A.I.R. diverter valve wiring, cold start injector.

It has been suggested that I sell the 1986 set up complete, and then locate a '88-'89 complete set up. Does that sound reasonable?

 

It is very possible to use any year set up TPI on your car. It just becomes more tricky. A MAF system can be converted to a MAP system. Vortec angle style bolts can be made to fit older style bolt holes. There is a site (Street and performance I think) that offers TPI conversion kits, ie (86-89) to (90-92). It all seems so easy once you find out how to do it and do it.

Wire harnesses can be re-pinned (very easy).

Alt. A./C pulleys and brackets can be changed.

Cold Start Injector blocked off.

AIr Diverter valve is just a mercury switch (or is that the EGR, been a week since I've done it)

If you want to save some money and time, you can do it, there is help out there.