Topic: Carb. Replacement
in Forum: C3 Engines
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mount airy, MD - USA
Joined: 8/27/2006
Posts: 71
Vette(s): 1981 Charcoal Met., Silver Interior, Gymkhana Suspension, 27K original miles. It's my daily driver.
Okay, what do you guys do when you replace the stock computer controlled carb with an aftermarket Holley or other brand non-computer controlled carb. ?
1981 Corvette, 26K original miles, charcoal gray, gymkhana suspension, AM/FM/8 track.
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Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Put a piece of black tape over the "Check Engine" light... 
(Sorry...it had to be said, and I couldn't help meself!)
The ECM on those cars really only controlled a couple of functions. Idle fuel metering, and..the timing. If you remove the sensors from the system that are part of the carb, the timing will suffer somewhat. The carb has the metering control solenoid, and a TPS(Throttle position Sensor). The TPS gives the ECM info on where the throttle is, and will adjust the timing to suit the load of the engine, and it adjusts the idle fuel mixture, for emissions. Replacing that carb with one that has no sensors will cause the "Check Eng." light to burn brightly, and will keep the ECM from doing any adjustments to the timing.
You can do it, but it might require the replacement of the distributor with a non-ECM controlled one. I'm sure there are others here who have found a way around all of this...
(Sorry...it had to be said, and I couldn't help meself!)
The ECM on those cars really only controlled a couple of functions. Idle fuel metering, and..the timing. If you remove the sensors from the system that are part of the carb, the timing will suffer somewhat. The carb has the metering control solenoid, and a TPS(Throttle position Sensor). The TPS gives the ECM info on where the throttle is, and will adjust the timing to suit the load of the engine, and it adjusts the idle fuel mixture, for emissions. Replacing that carb with one that has no sensors will cause the "Check Eng." light to burn brightly, and will keep the ECM from doing any adjustments to the timing.
You can do it, but it might require the replacement of the distributor with a non-ECM controlled one. I'm sure there are others here who have found a way around all of this...
Joel Adams
C3VR Lifetime Member #56 
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(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
Joel is exactly right.
I have done away with all the computer stuff in mine. Including all the wiring associated with it.
Even if I didn't go with a new crate engine, I would have used a Q-jet carb and a distributor from an '80 or earlier vette on the original engine.
There are no computer controls on those years, except for the '80 California emission LG4 305 cid vettes.
I removed the "Check Engine" bulb when I replaced all the dash and gauge lights. You can try to unplug the ECM after you replace the carb and distributor and see if the light stays off.
Feel free to ask more questions if you run into a bind.
TKO500 5 spd.
Borgeson Steering Box
Born 8/1981
Sequence #3975
Click here to see more pics of my Vette on CarDomain.
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Lifetime MemberIrving, TX - USA
Joined: 8/21/2004
Posts: 4273
Vette(s): #1 -1969 Corvette Coupe Riverside Gold, black interior,MN,A/C,350/350,PS,PB,window cranks.
#2 -2000 C5, black/black, 6 sp, Bose system & lots of buttons.
Yikes, a computer controlled carb?! That sucks........I agree......do away with all the computer stuff but keep the old stuff.
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MICK - C3VR Lifetime Member #113
in Forum: C3 Engines
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