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.

[Dieselsj]

Just to chime in... I went from an auto to a manual and started with a manual BIN. I really didn't like the IAC decay from the factory - RPMs would hang too long after taking my foot off the throttle. I ended up using all of the IAC settings from the auto bin.

You definitely want a VSS though.

[Dan Brown]

Gotta question for somebody in the know about the 1227747 ECM. The wiring schematic I'm going by shows pin C2 (brown wire) going to and Air Control Solenoid. What is this, and is it needed? Thx a lot for any help.

[Dieselsj]

Gotta question for somebody in the know about the 1227747 ECM. The wiring schematic I'm going by shows pin C2 (brown wire) going to and Air Control Solenoid. What is this, and is it needed? Thx a lot for any help.

This is to control the solenoid for the air injection into the manifolds. You do not need it. Make sure to disable the function in your tune.

[Dan Brown]

Thx Dieselsj. Do you know who I could send my PROM to, to get it tweaked. Troy Brown at Howell efi said he could do, but, if I don't have to, I'd prefer to find somebody cheaper than the 200 bucks he quoted me.

[Dieselsj]

Thx Dieselsj. Do you know who I could send my PROM to, to get it tweaked. Troy Brown at Howell efi said he could do, but, if I don't have to, I'd prefer to find somebody cheaper than the 200 bucks he quoted me.

For not much more than that, you could equip yourself to do your own. Unfortunately I don't have the equipment to erase those factory chips.

[dave w]

Myself and several other members can reprogram the original TBI chip. Post a thread asking for help.

dave w

[Dan Brown]

Anybody out there that can tweak the PROM from my 1227747 for my 1974 Chevy K10. I'll be glad to tell you everything about it an send you the PROM.

[Six_Shooter]

Sounds right about connecting the VSS.

Where are you located, there are members all over and one might be local to help you out with your PROM.

[Dan Brown]

I'm in Katy, Texas, right outside of Houston. If anybody is in my area please let me know on the Forum.

[dave w]

I'm in Katy, Texas, right outside of Houston. If anybody is in my area please let me know on the Forum.

A new post asking for help with a chip, outside of this tread will be seen more members.

dave w