ok so I heard and seen some pics along long time ago and there was a write up on how to convert.

I'll thell ya what it is for thows who dont know.
the best year is off a 1980 caddy fulsize with the 386 it has a 4bb q-jet but with some mods. It has a computer that looks at the timing, throttle postion, oxegen in the ehaust and engine temp. it gets this reading and bounces a needle in a jet (via a selonoyd) in the q-jet to controll the mixure. It bounces this needle about 60 times a second if the mixture is too rich it holds in the needle causing it to leen out. If the mixture is to leen it hold the needle in causing the mixutr to richen.

if you can find a 80caddy the swap is easy to a non computerized truck as long as you get the carb,computer,wiering harnes and sencers.

but I was wondering if any one has some pics of theis setup and has a write up on wich wire goes where. or knows where ther is one cuz I lost em


thanks

I have always stayed away from "computer-controled-carbs". My reasons for running a carb are:
1)It was already on the truck (a Q-jet)
2)You can fix it in the field
3)Easy to adjust

Computer-controled-carbs arn't any of those.

If I was going to swap in anything it would be FI! Why would you put all that work for a carb that will get you a few MPG more but none of the other benifits of FI? You won't gain more HP than a properly set-up carb or FI.

Bottom Line:
If I was going to go through all the work it would be for TPI

I can't help with the wiring or details of swapping in such a thing, but I've gotta agree that it's probably not a great idea. An old mechanical Q-jet modulates the rods with a power piston and vacuum spring. When properly set up, the mixture control is nearly as good as the electronic feedback carbs. No carburetor will provide an exact stoichiometric ratio, which is required for a three-way catalyst to function properly. As the EPA tightened emissions toward the end of the '70's and into the '80's many carbs just didn't cut it anymore - in '79 Chrysler dropped the Thermoquad in favor of the Quadrajet, as an example - for 2bbl. applications they kept the Carter BBD with a stepper motor (same electronic feedback deal) which proved to be a DISASTER as many of the Jeep owners will tell you. Ford's infamous POS, the Motorcraft Variable-Venturi, was IMO the most fecid objet to ever adorn any American automobile. As emissions got even tighter and the development of the three-way catalyst reached the production stage, no carburetor could provide the degree of mixture control needed and everyone switched en masse from carbs to EFI. My point is that the electronic feedback carbs are a transitional form between a pure carb and EFI; they are a curiosity, a relic, and deserve little more than a footnote in the history of the internal combustion engine. They combine all the bad aspects of a carb with all the bad aspects of EFI - complexity, very difficult to trail-fix, susceptible to electrical/electronic problems, etc.

I spent many years twisting wrenches, and have worked on more feedback carb. fuel sytems than I care to remember. They suck. There is nothing good about them. If you were closer, I'd slap you and give you one of my dear old dad's favorite lines; "What the HELL you thinkin' boy?"

it was just an idea.. fwak :rolleyes:


sorry for being ingnerent and wanting lo learn I gues next time I should have a pol to se if my question is a good question or a dumb question before I ask :rolleyes: :mad3:

It was a nice try.. Just think about it...
Here we have The worst of all worlds, A simple carb that is no longer simple, and a high tech computer from 20 years ago when they were just getting away from key-punch cards... :eek:

Run away from that combo fast.

Sorry Chief. I didn't mean to piss you off. It's just that I've got very strong feelings about these, earned the hard way. I'm always happy to help someone who wants to learn; just like a lot of other people here have been happy to help me with a question. I'm glad that you got my point. It would have been irresponsible for me to NOT make it, and let you waste a lot of time and money on something that you'd have been kicking youself in the ass for.