Which TBI system is better?

[KeyAir]

Good info, I will pull them if I can.
So, I am taking the TBI unit, Harness(marked every wire or left parts attached), sensors, Air filter, air injection setup(not the exhaust manifolds), smog pump, EGR, pipes and valves.
I managed to remove the whole TBI setup, except the coolant pipe that comes out of the back of the TBI unit... could not budge the fitting and could not release the hard pipe from the back of the head, so I cut it.

Removed the whole front accessories setup inc pulleys, alternator, smog pump, AC compressor, and brackets.

Chased all of the wiring thru the firewall on the pass side and released it from the ECU and pulled it back thru the firewall cleanly. Took the ECU out.
Could not get the wires out from the ECU to ALDL out, so I cut them each end as long as I could. I think I would have to lengthen that anyway.

Couple of questions...
Should I remove the Knock sensors? There looks to be 2...
I removed the harness as far as the fuse block on the drivers side firewall... how do I release that, or can I cut it off????

[KeyAir]

Still working on this.

Found and labeled the 1990 ECU and the 1987 ECU.
Both came off R2500 3/4t 2wd suburbans with TH400's

The 1990 is a 1227747?


And the 1987 is also a 1227747?


Does that mean that they are identical... or did I read the wrong number

[Nasty-Z]

Still working on this.

Found and labeled the 1990 ECU and the 1987 ECU.
Both came off R2500 3/4t 2wd suburbans with TH400's

The 1990 is a 1227747?


And the 1987 is also a 1227747?


Does that mean that they are identical... or did I read the wrong number

They are identical ECMs.

The 4 letter "code" that differs on each one , ANTY and AFTH , are the broadcast codes for the calibration , it is the larger of the two chips you will find under the cover , this is the only difference between the two units you have there.

TOM

[KeyAir]

Thanks Tom!

So here is what I am thinking...
The 1987 was my own vehicle for 15 years and I know it ran fine, but the 1990 was a non runner, so I have no reference point.

If I use the 1987 ECU, TBI, and smog gear, and as I have a copy of the title I can say that this is my engine swap for the California smog referee.
However, I would prefer to use the full, single serpentine belt drive from the 1990.
I will assume for now that the smog pump, and AIR system will be the same connections and function as they ran off the identical ECU...

The 1990 accessory drive looks like this...


And the 1987 was a mishmash of serpentine from crank to Smog Pump and Alternator, and V belts for PS, and AC... like this.

[Nasty-Z]

Just be sure if you use the 90 accessory drive you get the correct water pump when you replace it , the 90 setup with one serpentine belt uses a reverse rotation water pump whereas the 87 multi belt setup uses a standard rotation water pump.

I use the Edelbrock aluminum pumps for replacements on all of my stuff , good quality and improved cooling.

I would save that power steering pump and bracket setup off of the multi belt (87) engine , they go for some good money as they are sort of hard to find for the Camaro / Chevelle guys swapping to the BBC from a small block.

ECM will control the smog stuff with either belt setup . Do you absolutely need to run the smog pump ?

TOM

[KeyAir]

Sorry for the delay in responding...
Yes, the Smog pump MUST be there to make this pass smog.

I am working toward this conversion now, and have more questions.

What "Size" fuel feed and return pipes will I need? I have a return pipe, but it looks small diameter.