Will a PCM fire plugs on a carburated LT1

[rwd_pete]

I am working on a '29 Ford roadster and thinking about installing a sbc. For a Gen I engine you have to cut the firewall to clear the HEI distributor.

I was thinking I could use a smaller points distributor without the cap using a carbed Gen II engine. The points could make and break the circuit to the coil, firing through an Opti up front just for distributing the spark.

Then I ran across this old article from Hot Rod inferring a PCM could spark the engine using a GM Perf. carb intake (which I have). Then I could just put a freeze plug in the distributor hole.

Do you think the PCM would fire it with no injector hookup without going into limp home mode.

Currently the car has a 78 Regal carbed turbo V6 motor sitting in it, but it's seized from sitting for 30 years.

Pete
1997-08 Hot Rod Mag LT1 intake.jpg 20230419_29 Ford.jpg

[SSlowBoat]

I am working on a '29 Ford roadster and thinking about installing a sbc. For a Gen I engine you have to cut the firewall to clear the HEI distributor.

I was thinking I could use a smaller points distributor without the cap using a carbed Gen II engine. The points could make and break the circuit to the coil, firing through an Opti up front just for distributing the spark.

Then I ran across this old article from Hot Rod inferring a PCM could spark the engine using a GM Perf. carb intake (which I have). Then I could just put a freeze plug in the distributor hole.

Do you think the PCM would fire it with no injector hookup without going into limp home mode.

Currently the car has a 78 Regal carbed turbo V6 motor sitting in it, but it's seized from sitting for 30 years.

Pete
1997-08 Hot Rod Mag LT1 intake.jpg 20230419_29 Ford.jpg

i believe it would. there is not really a limp mode for these cars besides check engine light on and fans on.

im looking into using a carbed lt1 in a swap BUT using a ls ignition controller to drive 8 ls coils with a torqhead sensing unit

Sent from my SM-S908U using Tapatalk

[rwd_pete]

Thanks for your comment. My Impala SS went into a limp home mode once, but it was a tranny issue and it stayed in low gear. I guess that that's the tranny side of the PCM brain. The coil on plug setup sounds like a nice modern way to make it all work.
Pete

[SSlowBoat]

Thanks for your comment. My Impala SS went into a limp home mode once, but it was a tranny issue and it stayed in low gear. I guess that that's the tranny side of the PCM brain. The coil on plug setup sounds like a nice modern way to make it all work.
Pete

trans does have a limp home mode, as far as i know limp mode engine side is open loop speed density

Sent from my SM-S908U using Tapatalk

[Injuneer]

Supposedly there is a sub-program in the PCM that covers the limp mode. That is only intended to keep the engine running when almost all sensor input is lost. Key word… “supposedly”.

[SSlowBoat]

Supposedly there is a sub-program in the PCM that covers the limp mode. That is only intended to keep the engine running when almost all sensor input is lost. Key word… “supposedly”.

ill figure that out soon as osie and i are going to use a painless stand alone harness and run a motor on the stand

[Injuneer]

GM calls it “Back-Up Mode” (also known as limp-home mode). It would not be useful for anything other than moving the vehicle off the road. Uses only distributor reference pulses, throttle position, and coolant temp. Implemented when “ECM cannot operate normally”. Conditions causing:
- ECM volts less than 9 volts
- Cranking voltage less than 9volts
- ECM internal circuitry fails to ensure proper Computer Operating Pulses

This is from “gmtuners.com”. Not specific to the LT1, at one point mentions “PROM missing”, so I’m only assuming the definition was carried over to the fixed chip PCM’s.