ok i have just bought a wrecked 1990 IROC with a 350 TPI automatic with dual fans and 3.23 posi disc brake rear. my question is what all will i need to put this setup in my 1991 RS which is originally a 305 5 speed car. i want to keep the 5 speed.

can i use the wiring harness from the IROC in the RS?

can anybody give me a list of everything I need?

 

I would not waste your time with this converstion unless you really have a thing for TPI and like the look of it. Putting a TPI set-up on a 305 TBI motor will gain you only about 10hp and a slight broadening of the low and midrange power curve. I would sell the TPI stuff and use the cash to buy parts that will make your TBI faster.

 

what i am wanting to do is put the 350 TPI into the car where the 305 used to be, the 305 is nothing more than a boat anchor now.

i want to use:
350 TPI
T-5
Dual fans
3.23 posi disc brake rear
140 electric speedometer

all of this is coming out of a 84,000 mile IROC(1990).

my question is what all am i going to need to do it right?

and can i use the wiring harness that is already in the IROC or will i have to get a new one?

 

Use the wire harness, ECM and every sensor and such from the TPI. You will need a new fuel pump since TBI is a low pressure system and will not support the 40+ PSI TPI needs. Everything is pretty much bolt and go since you have a donor car but I would not use the stock 305 exhaust. See if you can at least get the manifolds and y-pipe from the TPI car.

 

i can take the gas tank from the IROC and bolt it on in place of the one that is on the RS right?


i was planning on using the exhuast off the IROC because it has the dual cat setup and a brand new RAVEN catback setup on it.

 

Why would you want to change the entire gas tank. Unless you have the baffled 1LE option the tanks are the exact same just with different pumps. So if anything, just swap pumps.

 

i figured that it would be a hell of a lot easier because i am going to have to take both tanks down anyway right?

 

Yes.

 

I don't know if this is the greatest idea, but i'll throw it out there anyway.
Howell can mod a TBI harness to work with MPFI or TPI. Might want to give them a call for details on that.

 

It would be just cheaper to start with a TPI harness.

 

is the harness that i have going to work out ok???

 

Bottom line is you want to swap everything from the IROC to the RS. Motor, ECM, sensors, wiring harness, exhaust, everything. I wouldnt bother swapping the fuel pump from car to car, while you have the RS fuel tank down anyway I'd put in a new TPI pump, maybe a higher psi one in case you decide down the road to really work the 350.

I would also swap suspension components. Springs, sway bars, shocks, they are all better on the IROC. Your RS will handle better with them. Don't forget that wonder bar.