Carb to TBI conversion

[Dan Brown]

I am currently putting a TBI system on my 1974 K10 with a 350 and Muncie SM465 manual transmission. I am using a 1227747 GM ECM. I was told that since I'm using a manual transmission that I don't need a VSS. Has anybody out there done this type of swap and can give me some tips. Thx a lot for any help.

[dave w]

The 1227747 is a good option for a manual transmission. GM used a VSS with manual transmissions and the 1227747. You can eliminate the need for a "Park" switch input wire with the manual transmission and 1227747.

I can help you with a starter chip, which is a stock manual chip modified with "stand-alone" programming. A starter chip is not a "performance chip". A starter chip is not a "tuned chip".

dave w

[1project2many]

I was told that since I'm using a manual transmission that I don't need a VSS. Has anybody out there done this type of swap and can give me some tips. Thx a lot for any help.

Hi Dan,
I've done several TBI swapsn and have tuned a number of 7747 ecm equipped vehicles. I always advise people to use a VSS. The 7747 uses vehicle speed to adjust IAC. Without a VSS signal the ecm does not provide adequate control of idle speed. Without VSS the ECM does not engage deceleration fuel properly. Without VSS the vehicle will not perform as well as a stock vehicle.

[Dan Brown]

I have a VSS that I got from Jags That Run (2PRS) and I think it's at least similar to a VSS that Painless Performance used to sell (60115). The 2PRS has two white wires and I was told that one wire is grounded and the other goes to the ECM pin A10 (brown wire). This is what a tech at Painless Performance told be. Is this correct? Thx a lot.

[Six_Shooter]

VSS, is required on all GM OBD1 ECMs for best results. The VSS is used by the ECM to control engine states (idle, accel, cruise, etc) and makes tuning under all conditions much easier and just plainly work better.

Yes people have run these ECMs, and others without a VSS, but it's simple to add one, so why not add one, you'll be glad you did.

[Dan Brown]

Thx Six_Shooter. I have a Jags That Run 2PRS which is similar to a VSS that Painless Performance used to sell. The 2PRS has two white wires and a tech at Painless told me that one of the white wires, doesn't matter which, is grounded and the other goes to pin A10 (brown wire) on the 1227747 ECM. If you know anything about the 2PRS, please tell me if this is also your understanding.