Moparts
Mopar Quadrajet ??
Posted By: poorboy
Mopar Quadrajet ?? - 03/22/13 02:05 AM
We picked up a Quadrajet off an 82-85 5th Ave to use on a different project.
That carb has an electronic operated bowl vent, but we are running a simple carb & electronic ignition, with no computer. Is the electronic bowl vent going to give us problems? Will everything still work if I ignore the stupid thing? Can I bypass it, and if so, how?
Gene
Posted By: Kern Dog
Re: Mopar Quadrajet ?? - 03/22/13 06:36 AM
I thought that the Mopar Qjets were like the Chevy ones in function. Some had a fuel enrichment solenoid for cold start, but otherwise they worked like any older Qjet.
Posted By: ChinooK440
Re: Mopar Quadrajet ?? - 03/22/13 02:26 PM
I think what your calling an electric vent MIGHT be a mixture control solenoid which would be an electronic feedback carb. that needs a computer and associated sensors etc. to run correctly.
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I think what your calling an electric vent MIGHT be a mixture control solenoid which would be an electronic feedback carb. that needs a computer and associated sensors etc. to run correctly.
it may have the mettering needles that get a pulse/noid for the idle mixture.
IMHO,I would grind the shaft and remove the mopar throttle lever,find a older chebby carb from a 327/350, weld the mopar throttle lever onto the chebby carb throttle shaft.
this way all of the mopar throttle linkage/TV linkage hooks up correctly.
I am running a 1974 chebby q-jet on my roller cam 318 in the 85 truck.
hugh jorgan sent me a newish 1905 edelbrock q-jet/thermobog replacment carb for 72-85 dodge truck with 360/400/440(they dont make them any more) which is awsome with a working elect choke. 
it shows a mopar throttle adaptor in the owner manual for it,but the lever looks almost identical to the mopar lever I use.
I just put the stock throttle stud in and it all adjusted out great with the stock throttle bracket/1-piece rod TV linkage for the mid 80s trucks.
do you have the intake bracket with correct rod/trans lever?(I have 2 set ups if you need one)
I have a few q-jets that I grabed up for future mods to fit mopar. 
Posted By: Fury Fan
Re: Mopar Quadrajet ?? - 03/22/13 09:14 PM
Quote:
I think what your calling an electric vent MIGHT be a mixture control solenoid which would be an electronic feedback carb. that needs a computer and associated sensors etc. to run correctly.
with this and Scratchin'.
If that truly came off a 5th it wasn't the original carb, OEM was T-quad until '87 I think, then was feedback Qjet with spark and fueling computer (often mis-named as Leanburn).
Either way, I don't think 5ths ever got a 4-v, I think later ones of the feedback era got electronic Holley 2-barrels.
So, figure out for sure what you have and what that solenoid is. If it's a GM carb it could be from teh early 80s and with a solenoid bowl vent or something.
Posted By: dogdays
Re: Mopar Quadrajet ?? - 03/22/13 09:35 PM
No late model Fifths with a 4-barrel.
There is another thing that GM did with the Q-jets and the electric valve. On some they used it to block off a p[ortion of the float bowl for evap emissions, I believe. You really don't know until you take it apart.
There is a number on the back of the carb, each Q-jet had a code. Look online for decoding quadrajets and you'll see what I mean. I recently bought a raft of high altitude and California emissions Q-jets for mileage work in the mountains. Once you learn the code it's all downhill.
SFT, the Edelbrock Q-jet is a choice piece, I have bought three over the years, cheapest one was something like $80. The most expensive one was like $120. It looks to me that Edelbrock started out with regulation Rochester bodies.
R.
Posted By: Biggie
Re: Mopar Quadrajet ?? - 03/22/13 11:47 PM
Here is a internet pic of the carb we have. We need to know what the blue plug in goes to
IIRC that blue plug is the noid for pulsing the metering needles.
IIRC I have a carb in the shed that is apart. i will go take a pic of the inside of one.
dog,the edelbrock 1905 were new casting to start with.it works like no other q-jet I have had. the choke works,its not worn out, and it was FREE!!
wow! what a kick it has on the 440 over the 600 eddy carb.
Posted By: Kern Dog
Re: Mopar Quadrajet ?? - 03/23/13 01:06 AM
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..... in the shed that is ....
I have read many, many references to this " shed ". I'll bet it is huge! 
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Quote:
..... in the shed that is ....
I have read many, many references to this " shed ". I'll bet it is huge!
it has been called a magic shed in many GGA post as well.
here is the old one after the oak tree fell and was removed from top of it. good thing the 440 truck was out of the way.
here is the new replacement shed. 12x20
Posted By: Hugh Jorgan
Re: Mopar Quadrajet ?? - 03/23/13 03:31 AM
New shed needs more "stuff"....
I have an idea...
Posted By: Rug_Trucker
Re: Mopar Quadrajet ?? - 03/23/13 08:20 AM
The truck Mopar Qjets don't have all that crap on them. I pulled one from a 86 van. My van engine came with a 87 Qjet.
Posted By: Challenger 1
Re: Mopar Quadrajet ?? - 03/23/13 12:34 PM
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here is the new replacement shed. 12x20
I think I see a sink hole opening up? 
Posted By: dodgeram440
Re: Mopar Quadrajet ?? - 03/24/13 12:34 AM
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here is the new replacement shed. 12x20
That's the shed on the left, right? Has to be to be big enough to hold all your goodies. 
Posted By: dogdays
Re: Mopar Quadrajet ?? - 03/25/13 06:08 PM
To the OP: Do a basic Google search for "quadrajet identification" and you will find more info than you can use.
To SFT: I will look at my Edelbrock Q-jets when I get home tonight and see where the body casting came from. Maybe they were produced by Weber, or maybe by Rochester.
R.
Posted By: QuickDodge
Re: Mopar Quadrajet ?? - 03/26/13 02:22 PM
I believe 1986 was the first year Mopar used the computer controlled Q-jet. It was used on the Grand Fury and Diplomat police cars and maybe other models. I don't know if that carb was used on the 5th Avenues.
I've wondered if the mixture control valve in one of these computer controlled carbs could be manipulated to make an engine run lean to improve gas mileage? I worked on one of the ex-police cars years back that had the computer controlled carb. That car was running full rich and getting single digit gas mileage. I don't know how an engine would perform if the carb was stuck at full lean. If driveability was acceptable it may get great fuel mileage.
Posted By: poorboy
Re: Mopar Quadrajet ?? - 03/27/13 02:27 AM
The old guy we got the Quadrajet from said it was off a "Police Interceptor", but then everything he had was off a Police Interceptor. The number crosses over to an 82-87 Dodge & Plymouth 318 car.
It is the feedback carb, (picture posted earlier) and we intend on using it on my son's 331 Hemi. I would like very much to figure out a way to make this thing work. I would not be opposed to having it "stick" at the midpoint between rich & lean, if we can determine how to go about that. The carb looked pretty good, and I put a kit in it, but must have messed that up because we have a loud whistle at idle. I'm going to pull the carb back off and see if I can find the whistle problem, I'm hoping its not throttle bushings. Gene
Posted By: Fury Fan
Re: Mopar Quadrajet ?? - 03/27/13 02:55 PM
To use that carb the first question we need to answer is:
Does that solenoid need a PWM signal or a varying-voltage signal to operate as the OEM intended???
If PWM, you'd need a special module to make that work.
If voltage, a simple potentiometer would work.
Either way, you'll need some way to monitor the adjustment vs AF ratio. But I guess if you use the adjustment only on the highway, you could simply lean it out until it starts to misfire.
To make it automatic, a vacuum switch of suitable range could be wired to trigger a relay that energizes the 'noid circuitry. Might not be real smooth when it kicks in/out, though, but a 'car guy' might find that to be useful feedback.
Posted By: Rug_Trucker
Re: Mopar Quadrajet ?? - 03/27/13 03:42 PM
A whistle maybe the throttle shaft. When the shaft gets sloppy, the butterflies hang up onthese carbs.
Quote:
To use that carb the first question we need to answer is:
Does that solenoid need a PWM signal or a varying-voltage signal to operate as the OEM intended???
If PWM, you'd need a special module to make that work.
If voltage, a simple potentiometer would work.
Either way, you'll need some way to monitor the adjustment vs AF ratio. But I guess if you use the adjustment only on the highway, you could simply lean it out until it starts to misfire.
To make it automatic, a vacuum switch of suitable range could be wired to trigger a relay that energizes the 'noid circuitry. Might not be real smooth when it kicks in/out, though, but a 'car guy' might find that to be useful feedback.
I looked in the shed for mine,must have tossed it. 
I have a a q-jet you can have if you need one. I dont see that one working with out a ecm with all the bells whistles. it does not have the power piston/spring like a older q-jet.
I will swap you a 650 DP spredbore holley for the mopar throttle lever off of it. 
I have used the wrong gaskets mix matching stuff and had a whistle. check that the base gasket/throttle gasket fits the intake/main body and seals.
check to make sure there is no vac leak in the main body choke port if the choke is striped off.
Posted By: moretoys
Re: Mopar Quadrajet ?? - 03/28/13 01:39 AM
the blue plug is for the mixture solenoid and the white one is a throttle position sensor.you're not gonna get those to work without a computer.that is a computer controlled carb. might work without the electronics hooked up.make sure you stretch the spring for the power enrichment.clean the rods.check for worn throttle shafts also.Very common on an older unit.check the bottom of the float bowl.there is a plug down there.make sure it's still sealed.or it will always run rich/hard start as it will slowly drip gas into the intake.
Posted By: poorboy
Re: Mopar Quadrajet ?? - 03/28/13 04:32 AM
Well, I believe I've found my whistle. I had carb base gaskets that did not seal.
the original 4bbl intake we are using had the old little square Carter. The 3 sources we checked could not locate a kit for the old Carter. Our remaining choices were a well used Carter AVS, a Thermoquad, and the Quadrajet. The Quadrajet won out because it was the best looking (cleanest, most complete, and most unmolested) one to start with and the electric choke was a huge + because there was no choke provision on the intake. Being too cheap to buy Hotheads $50 adapter, I spent several hours making one (real cost effective) then I had to add the spread bore adapter on top of that (if you counting, that makes 3 carb base gaskets) The base gasket between the spread bore adapter and my home made adapter was the one that did not seal. I'm sure homemade gaskets didn't help much either.
So today I filed my homemade adapter more flat (again), made new gaskets, used weatherstripping glue on top of the home made adapter, and bolted the whole mess together again. It lasted until the motor warmed up and then the whistle started coming back.
Time to regroup and rethink the process. The fix is only $400 away. Gene
Posted By: Rug_Trucker
Re: Mopar Quadrajet ?? - 03/28/13 07:40 AM
Were you trying to find a kit for a Carter WCFB? I am willing to bet they can be found.
Posted By: poorboy
Re: Mopar Quadrajet ?? - 03/29/13 03:13 AM
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Were you trying to find a kit for a Carter WCFB? I am willing to bet they can be found.
Yep, that's the one! According to everyone we checked with, they show no kit available for the carb numbers we have. Supposedly it was made in early 54 and was 54 only. One source could "make" us a kit for around $100. Don't think so.
The ball is in Biggie's court now, its his car, his money.
Scratch, could you send the info you sent to me to Biggie (the guy earlier in this thread that posted the picture of our carb)? I have no clue how to forward a PM. Gene