355 TBI converting to TPI....with a T-5 questions - Third Generation F-Body Message Boards

FYRCHKN · 10-10-2009, 12:10 AM

I hate to seem like such a noob, but I've searched and read until my eyes have almost crossed for the past week and I'm still completely lost.

I doubt it makes a difference but if it does then here's a little history on my car. It started out as an LO3/700R4. I swapped in a non WC T-5 a couple of years ago. Then in April of this year I swapped in a decently built 355 TBI and a WC T-5.

Tomorrow I am going to pick up a complete TPI setup from an '86 IROC. It comes with complete intake(injectors, fuel rails, etc..), wiring harness, MAF, and ECM.

I have to admit that I'm a little torn on which route to go with this. Should I install all the MAF stuff or convert it all to SD?

I have read the sticky at the top on how to re-pin the TBI harness for SD and that seems pretty straight forward. But, that means that I have to hunt down the 7730 ECM and the connectors. I have been told that there's a good chance that my 8746 ECM could work and that all I would really have to do is splice in the 8 injector pig tails. Is there any truth to this? I don't have a clue on where to begin with prom burning or tuning, but a member of my local club if fairly knowledgeable in this area.

I know that the 350/T-5 combo was never offered so my main question is which setup would be the easiest to get tuned properly? MAF or MAP?

I'm running a 350 block from a 96 truck bored .030 with ported LO3 heads. My CR is 9.8:1 and my cam is 211/221 @ .050 110 lobe separation.

I'm just trying to make it a fun street car that might see the track once or twice a year in the future. Any help pointing me in the right direction would be greatly appriciated.

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FYRCHKN · 10-10-2009, 11:29 AM

Anybody?

Dyno Don · 10-10-2009, 11:56 AM

First things first....you can't use a MAF harness on a '91 (pinouts don't match)

Next, you need to get rid of that 110 LSA cam, it would be a nightmare to tune.

Repinning the TBI harness is the best bet with the 7730 and memcal.

The 8746 computer is also a nightmare as the chips are getting hard to find.
You could go the EBL route, but that's expensive.

HTH

FYRCHKN · 10-10-2009, 07:27 PM

Ok, I've decided to try to find a 7730 and the plugs to re-pin my TBI
harness since that seems like the easiest way to go. I'm assuming I can still splice in the injector plugs from the MAF harness.

Just out of curiosity, why is the 110 LSA cam so hard to tune? I've been running it for about 6 months with my TBI and the car runs great. I only have a mail order chip.

There is a member of my local club that has all the stuff to tune SD and I'm pretty sure I can get him to help me out. There is also another member that has a 350TPI/T-5 that is SD. He's already said that I could copy his chip so that I could at least get it running.

charlielamb · 11-19-2009, 11:22 PM

Quote:

Originally Posted by Dyno Don

First things first....you can't use a MAF harness on a '91 (pinouts don't match)

Next, you need to get rid of that 110 LSA cam, it would be a nightmare to tune.

Repinning the TBI harness is the best bet with the 7730 and memcal.

The 8746 computer is also a nightmare as the chips are getting hard to find.
You could go the EBL route, but that's expensive.

HTH

hold on you cant switch it because it is a 91? i have a 91 and im in the same exact boat, my car used to be a 305 tbi with a 700r4 now i got a 350 tbi and a t-5 i am getting a complete wiring harness, computer, and intake setup from a 1987 gta with a 305 auto, what do i need to do?