My God where do you people get your information? Computer only controls timing? Car originally didn't use an O2 sensor? I stopped reading after that....
Changing to quadrajet
- Thread starter eugrides
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Do a heated oxygen sensor conversion, key on 12 volts, a ground and add a bung in your headers. Another thing to consider is without the computer is no torque converter lock up. Either a toggle switch or controller is needed.
We-ell, I can only speak for myself and what I have personally encountered. The computer? system that I removed from my personal 1985 Monte Carlo SS, 4 Barrel Q-Jet, TH200-R4 was essentially a burned out crispy critter when I pulled it out from behind the passenger side kick panel. The power wires for it had been detached down at the solenoid because they were totally fried. There was no evidence of an O-2 sensor or its corpse, in the exhaust pipe, or the remains of a wiring harness that could have been for it hanging anywhere. Of course the cat was long gone so it might have gone along with it at the hands of whichever previous owner did that edit job.
When I did the research for that Q-Jet, I was informed that, as originally delivered, the carb that came with the car supposedly had had some type of electronic control attached to it and that the distributor advance was also slaved to this device. Mis-information is, of course, always possible but I do know that I had a miserable time getting the distributor that came with the car to work with the Q-Jet that was on the motor. If I set it correctly for retard so it would start and idle, the rest of the advance curve would suck. Any tweaks to the idle timing to get more response and it would diesel. It is perfectly possible that what came with the car was not the factory original carb; Hey, 25 plus years consisting of various owners during that time before it came into my hands; things tend to wear out and get replaced with what is available, not necessarily what is politically or mechanically correct. In any event, that carb is now a paper weight and the distributor is on the bench awaiting dismantling and disposal. I have other older versions that I can plug in as replacements. And I did also get rid of that "x-mas tree" multiple tube vacuum switch that had been screwed into the thermostat housing because most of the vacuum lines that used to have been attached to it had disappeared as well.
Oh, yeah, computer system is a misnomer. I did take a moment to do an autopsy on the remains of that so-called computer and it was nothing more than a couple of boards with a few circuits on them. No recognizable memory chips and nothing that looked like a processor or cpu. Most of what was in there looked like it had been submerged in mild acid for a decade or so. OBD I is a term I am given to understand applies to the first generation of on board computers. There was a socket attached to the dash that was harnessed to the plugs for the computer, which I take to mean that a reader could be used to pull codes? My Bosch/OTC OBDII scanner has a subroutine loaded to it for OBDI but it has never been accessed, never mind run.
All the above is simply by way of preface. My point, above, and now, is simply that there are a lot of options available. The initiator of this thread doesn't have to stick to what came from the factory 35 years ago unless he is faced with some compelling legal reason to do so. If not, then his options are limited either by what he wants to end up with in terms of how his vehicle performs, or by what his pocket book allows him to do, or a combination of both.
Nick
When I did the research for that Q-Jet, I was informed that, as originally delivered, the carb that came with the car supposedly had had some type of electronic control attached to it and that the distributor advance was also slaved to this device. Mis-information is, of course, always possible but I do know that I had a miserable time getting the distributor that came with the car to work with the Q-Jet that was on the motor. If I set it correctly for retard so it would start and idle, the rest of the advance curve would suck. Any tweaks to the idle timing to get more response and it would diesel. It is perfectly possible that what came with the car was not the factory original carb; Hey, 25 plus years consisting of various owners during that time before it came into my hands; things tend to wear out and get replaced with what is available, not necessarily what is politically or mechanically correct. In any event, that carb is now a paper weight and the distributor is on the bench awaiting dismantling and disposal. I have other older versions that I can plug in as replacements. And I did also get rid of that "x-mas tree" multiple tube vacuum switch that had been screwed into the thermostat housing because most of the vacuum lines that used to have been attached to it had disappeared as well.
Oh, yeah, computer system is a misnomer. I did take a moment to do an autopsy on the remains of that so-called computer and it was nothing more than a couple of boards with a few circuits on them. No recognizable memory chips and nothing that looked like a processor or cpu. Most of what was in there looked like it had been submerged in mild acid for a decade or so. OBD I is a term I am given to understand applies to the first generation of on board computers. There was a socket attached to the dash that was harnessed to the plugs for the computer, which I take to mean that a reader could be used to pull codes? My Bosch/OTC OBDII scanner has a subroutine loaded to it for OBDI but it has never been accessed, never mind run.
All the above is simply by way of preface. My point, above, and now, is simply that there are a lot of options available. The initiator of this thread doesn't have to stick to what came from the factory 35 years ago unless he is faced with some compelling legal reason to do so. If not, then his options are limited either by what he wants to end up with in terms of how his vehicle performs, or by what his pocket book allows him to do, or a combination of both.
Nick
Huh! Actually had to go back and reread what I posted,. That's on me, there should have been a comma between the TH200-R4, and the "was" which started the rest of the sentence. For clarity, it was the computer? that was the crispy critter. Now it is an ex-computer, it has ceased to be. I actually did keep part of its aluminum case for the metal but recycled most of it for scrap.
It just depends what was done to the car and the future plans. Only the map sensor and ECM were left in my 88 when I got it. So many wires were cut and burnt and their was a non CCC 83 307, they were in Canada up till 86. I was planning a 403 swap and just too much work, for what gain? The only emissions devices up here were an air pump, cat and a super lean mixture pre 86. I also saw anywhere from 13 to 22 degrees timing at 1100, only cast iron intakes on B/C/D bodies till 85 and weird things like 5 pin HEI modules. Of course almost all the G bodies were sbc 305 powered up here, also non CCC except the H/O and 442 till 86.
Hi Guys. Just for the record . The ECM [Computer} controls spark timing, Carburetor mixture and when the torque converter locks up. Just removed my ECM on an 84 3.8 V-6. I used an early 1980 Distributor without EST [Timing Control] got it from Rock Auto about 100.00 no core charge, I bought a dualjet [2bbl] on ebay also about 100.00. Q-Jets are available. Try and research the carb numbers for an 1980 Q-Jet then get one that closely matches #'s. Also a 1980 fitment. without Mixture Control Solenoid or Electric Idle Speed motor. I removed the computer from the right side kick panel and removed ALL the ECM wiring Harness including the Oxygen Sensor. As it will only work with and ECM on Board.I have worked on several CCC Controlled GM cars and they are a pain in the A-- to tune given how basic the computer is designed as well as the fact that they were poorly made to begin with. So if your state will allow you to title/register your car without and emission/Smog test i recommend to go this route. It is fairly simple and not nearly as expensive as trying to tune with the ECM in place. Good Luck !!
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