i was wondering if the tpi wiring was the same for the 305 and 350 the car had tpi but it was a 305. i bought it with the carbed 350. whenever they swapped the engine they left the harness and wiring for the tpi. i wanted to know if it would be a direct swap or if not how much work would be needed?
could i get the tpi setup and just put it on my 350?

 

The LB9 and L98 engines use the same TPI hardware minus the PROM and stock injectors from 1986 through 1992. Early 1985 TPI systems were slightly different. Though I can't think of a reason why they wouldn't work given proper ECM programing. (If possible.) If you have the wiring you may only need the TPI ECM if it isn't in the car. The LB9 (305) engine came with 19lb injectors while the L98/B2L (350) came with 22# injectors. I've got a carbed car with the TPI wiring harness, but the stock ECM is still in the car. You might be in a similar situation.

 

'85 TPI - 305 only, unique to that year. Not a very capable ECM. Not completely sure, but I believe the pin-outs were different from later years.

'86-'88 TPI - basically the same, 350 first available in '87. However, the base mounting changed from all 90 degree bolts to the center two on each side being at 72 degrees in '87.

'89 TPI - basically the same as '86-'88, but no cold start injector. Available in both 305 and 350. Unique to that year.

'90-'92 TPI - changed from MAF to speed density (MAP). Available in 305 & 350, various programming and other details within those model years.

If you get a system from one of the groups above, the wiring & ECM need to be from the same group. However, 305 or 350 isn't important for the wiring within each group. SD is the most sensitive to changes such as engine displacement.

If your username means you have an '89, and the TPI stuff in the car is '89 model year, you'll need '87-'89 stuff (the cold start injector can just be left plugging the hole if you get), assuming your 350 has '87-up heads. If '86-earlier heads, it would be easier to use an '85 or '86 base. For the sake of simplicity (and perhaps sanity), it would be best to avoid '90-'92 hardware - unless you're willing to convert to SD.

 

The wiring harness is unique to the 1985 cars. Also the ECM is different than it was in later years. The plenum, runners and injector are compatible, but if you are going to use them on newer TPI engines, or with newer TPI wiring, you will need to make some changes. The 1985 TPI setup has the 9th injector for cold starts. You can plug the hole and remove the injector, or you can disconnect the injector all together but leave it in place. The actual plenum and throttle body are all the same. As for the different intake manifold I think you are right on the money. 90-92 hardware is fine but only if you are getting a complete TPI setup from one of those cars and you are using it on a 1986 or newer car. It is my understanding that MAF is actually capable of handing higher HP/TQ applications than speed density is, but I am not sure what their maximum capability is number wise. Speed density TPI eliminates the MAF and the duct work which makes for a cleaner setup which I like.

 

It was my understanding that it was the other way around. The 3rd gen MAF is limited to about 500 CFM.

Speed density TPI eliminates the MAF and the duct work which makes for a cleaner setup which I like.[/QUOTE]
And you aren't restricted by the restrictive MAF.

 

And you aren't restricted by the restrictive MAF.[/QUOTE]

I might have that backwards.