computer prom
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Joined: May 2005
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From: Lincolnton NC
computer prom
After swapping out my TH350 automatic tran.out of my '81, for a 4 speed Muncie, I find out to get optimum gas milage, I'll need to swap my "automatic" computer for a computer out of a 1981 with a manual tranny. Actually, the "PROM" (computer chip) is all I actually need to switch.
Swell...I haven't been able to find one, either the entire computer w/Prom, or just the PROM.
I thought I would go the Hypertech route, but that requires using 93 octane & I don't need the extra expense.
Does anyone MAKE these chips? I know GM doesn't ., nor do they have any.
Or, where would you suggest looking for one...other than breaking and entering....I've tried most of the salvage yards. thanks again, jim
Swell...I haven't been able to find one, either the entire computer w/Prom, or just the PROM.
I thought I would go the Hypertech route, but that requires using 93 octane & I don't need the extra expense.
Does anyone MAKE these chips? I know GM doesn't ., nor do they have any.
Or, where would you suggest looking for one...other than breaking and entering....I've tried most of the salvage yards. thanks again, jim
Burning Brakes
Joined: Aug 2002
Posts: 1,146
Likes: 10
From: Scottsboro Alabama
Jim, if my computer was for a 4-speed I would just give it to you. That part will be hard to find. Try calling Gary Gruhala 636-586-3909. I bought my clutch pedal assembly and a few other things from him. He doesn't overcharge and he's great to deal with. If he can't help you he might be able to steer you in the direction to someone who can. Good luck! 
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Joined: Jul 2005
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From: Florida
I would double check that. As far as I know th350 have no wires running to the computer. The computer just controls the carb air fuel and other emission stuff. You can get a custom chip they run $100 to $150. You are very limited as to the things you can do with computer controlled carbs as far as the computer goes. I have an 81 with the factory setup like yours, mine is auto. Around town It is a killer on gas 10 to 12 MPG, on the HWY I get 29MPG. If you really want to get better gas mileage save up and convert to TPI. That is the way I'm going.
Race Director
Joined: Jul 2004
Posts: 12,705
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From: Scottsdale Arizona
Originally Posted by Mr.L
I would double check that. As far as I know th350 have no wires running to the computer. The computer just controls the carb air fuel and other emission stuff. You can get a custom chip they run $100 to $150. You are very limited as to the things you can do with computer controlled carbs as far as the computer goes. I have an 81 with the factory setup like yours, mine is auto. Around town It is a killer on gas 10 to 12 MPG, on the HWY I get 29MPG. If you really want to get better gas mileage save up and convert to TPI. That is the way I'm going.
Race Director
Joined: Dec 1999
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the ECM takes a reading off the VSS, it's behind the cluster, a blue or yellow box w/ an optical emitter/sensor in the back of the speedo. Also the ECM controls the metering rods depending on load and the ignition advance/knock retard. There is a difference between the auto and manual..however I would just pull all that stuff off get some nice performance parts on there and truely enjoy the manual.
