I have an 1985 IROC-Z 305 TPI that I want to swap in a 5 speed manual.If the 85 computers only work in 85 cars..and no 5 speed TPI was available in 85 what can I do?Use the automatic chip?HELP!!Thanks.

 

get HITHERE PROM for an 87 with HITHERE manual. HITHERE cant remember though if 85 had the same comptuer

 

Cant do that, different computer.

Probably your best bet is to take the stock computer and throw it away. Swap to HITHERE SD system. Mike Davis (if you look up his name, should find HITHERE post or two) and head over to his website, he has the info you need on the swap. Only other choice is to modify the chip, but HITHERE'm not sure if anyone has found what you need to change or not. Can try searching the PROM board for info on the 870 (HITHERE think) ecm.

 

Thanks!!

 

I did the 5-speed swap (along with another motor) and I also swapped to the 86-89 ECM. I swapped to an 87 harness instead of repinning mine. It was easy, and now I have a complete 85 TPI setup that I can throw back onto my stock 305.

But anyway... it is possible to burn a PROM for the 5-speed, but there are not many people that are very familiar with the 85 ECM, so you'll pretty much be on your own when it comes to PROM tuning.

 

I converted my 85 to a 5 speed and used the stock auto computer for a while with no problems. I did the same as everyone else though and eventually upgraded my computer to the newer design.
Good Luck!

 

85TPI400,

This goes maybe little off to topic,but did you run 400cid motor with 870 computer?(stock prom/modified prom)I ask because I think to put someday biggerinch motor to my -85 z,and not sure how original prom works with it. I did read somewhere that there is no big differences between -85 350/305 injector constant(-85 350 uses 24 lbs injectors and ??psi fuel pressure versus 19lbs/43 psi.How about ignition curves?

Jari

 

Jari,
When I put the 400 in my car, I upgraded the computer and also swapped back to an auto. I have used an ADS 350 prom with the fuel pressure cranked up a bit until now with no problems and great driveability since it was a somewhat tame 400, (good vacuum and about the same overall powerband as a stock 350, but with much more torque) I have the engine out again and I am adding a ton of new upgrades but now I am almost sure I will reqiure prom tuning. I think it is time fo me to get on the prom burning board and start learning how to do it.
Hope this info helps a little,
Tony