I'm swapping the motor and tranny from my 86 IROC to my 91 RS. The motor is a 99 Vortec 350 w/Hot Cam, Vortec Heads, Free Ram Air, Vortec TPI base, SLP runners, ported plenum, SLP 1 3/4" Headers, 2001 Ws6 Cat Back. Tranny is 96 T56. Gear is 3.73.

Miraculously, this has all been running off of the stock 5.0L TPI chip in my 86 IROC. My 91 had the 5.0L TBI motor.

Should I just swap in the 86 Wiring and computer to the 91 body and get my chip reprogrammed and maybe a Wells SU-145 MAF sensor? If so could I convert to the newer external coil distributor?

Or should I go ahead and convert the 91 Wiring to SD TPI?
What would I need? How much harder would it be than just swapping over the MAF system?

Thanks

 

91s have that VATS thing in the key. you can leave it unhooked with the 86 ecm. on my 91 z28 the air bag somehow hooks into the ecm. I don't know why buy its 461org on A8, my wiring diagram shows it as a data line. what ever that is. It may just tell the ecm to blink the dash light.

For a long time I had a stock 305 chip with a 350 an slp cam and trick flow heads. It ran fine I just put 24lb/hr injectors in it. Oh yea it went 13.1@106 with a 5 speed when I put the 6 speed in it slowed down a little. it would just bog or spin I think the 1st gear sucks but it still went 13.3@104 but only once.

good luck with what will be one really nice 3rd gen.

 

Thanks for the reply.
I'm leaning towards the notion of just swapping in the engine control harness and ECM from the 86. I'll also swap the dash harness since I'm gonna swap the dash and sterring column from the 86 also. That will solve the airbag and VATS problems.

I'm gonna replace the induction and fuel management system with the Edelbrock Pro-Flo system once I have the other areas of the car finished. So there is no need for me to bother with converting to SD.

Now I just need to find out if I can convert the Distributor from the 86 computer controlled HEI to the 91 Remote Coil HEI one.
I'm gonna be rewiring my ignition anyways since I'm gonna be putting a hidden coil kill switch and fuel pump kill switch in anyways.

Draino

 

the dist. swap is a fairly simple deal. you will find the cleanest way is to work foward to the distributor and coil from the weatherpack 4 way connector that used to feed the big cap dist. 4 way has A,B,C,D, and each has a wire color that you need to ensure is maintained to the new module. it would be too easy for ya if the general kept each letter on the plug corresponding to only 1 color of wire for the duration of the production. the colors are always going to be present, and do the same thing electrically but not always in the same letter connector cavity.its this: black with a red stripe= ground from dist. to ecm. circuit#453 usually "D". tan with black stripe=timing bypass ckt.#424 usually "C". purple with white stripe=est ref.hi ckt#430 usually "B" white=electronic spark timing ckt#423 usually "A" you will prolly use a spliced together mix of the 2 harnesses to get you to the ign. module 4 way plug on the new small dist. just match colors, if in doubt. buy the 2 wire pigtail (coil to ign. module) from gm or a wrecking yard pink=switched ign-take 12v from thewire that once hooked to the big cap at the cap terminal "bat" labeled and finally white(again) it feeds this, hint, 2 words-tak ometur. hope some of this helps get you where your goin. even chiltons will have a rudimentary schematic available, haynes manuals for sure.