diff between 85 and 86 ccqjet
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Joined: Jul 1999
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From: Cookeville, TN
diff between 85 and 86 ccqjet
so far as i can tell, one extra vacuum port down by the capped screws that you aren't supposed to tamper with - my question is, i drove the car with the 85 carb, and just let the hose dangle free - didn't notice any diff until i filled up my ghas tank - it had a large vaccuum and made a long sucking noise - i traced the tube back, and it goes to the black relay type thing for the charcoal canister - my question is, i like the way the 85 carb responds alot more than the 86 carb (that has the extra vacuum port) - so can i split another vaccuum port somewheres?
also i noticed that there is a smaller vacuum port by the 3-prong plug on the side - anyone have any idea what it goes to? mine wasn't plugged into anything, and wasn't capped - i capped it with no noticable diff (driving or rpm wise)
also i noticed that there is a smaller vacuum port by the 3-prong plug on the side - anyone have any idea what it goes to? mine wasn't plugged into anything, and wasn't capped - i capped it with no noticable diff (driving or rpm wise)
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Joined: Jul 1999
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From: Cookeville, TN
lol, i forgot some info - i'm still a little wavery from all the gas fumes of rebuilding the carb...
my car is an 86 sport coupe lg4, and the carb i rebuilt for it is an 85 - it has one less vaccuum port
maybe that makes a little more sense...
my car is an 86 sport coupe lg4, and the carb i rebuilt for it is an 85 - it has one less vaccuum port
maybe that makes a little more sense...
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Joined: Sep 1999
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From: Philly, PA
The later the modle, the more ports it had on it. In all likelyhood the extra port can simply be capped and forgotten about.
However, it is best to check the acutal FUNCTION of each vacuum port one carb versus the other. SOmetimes 2 ports in identical locations will have different fuctions on 2 different year carbs- one year it's a full vacuum source, the nest year a ported one, etc.
85 and 86 computer controlled QJets should be mechanically identical in their functioning with only minor differences, in general.
However, it is best to check the acutal FUNCTION of each vacuum port one carb versus the other. SOmetimes 2 ports in identical locations will have different fuctions on 2 different year carbs- one year it's a full vacuum source, the nest year a ported one, etc.
85 and 86 computer controlled QJets should be mechanically identical in their functioning with only minor differences, in general.
Thread Starter
Junior Member
Joined: Jul 1999
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From: Cookeville, TN
the thing is, i wanna go from an 86 to an 85, and wonder if there is a place i can splice in that extra vaccum line that goes to the charcoal canister
anyone know what type of vaccuum port i need?
anyone know what type of vaccuum port i need?
Supreme Member
Joined: Sep 1999
Posts: 7,072
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From: Philly, PA
You're gonna have to determine what kind of vacuum port it is on the 86 carb and then find a same or similar port on the older 85 carb and then "T" the line into it.
Is it full manifold vacuum at all times, is it a vacuum port that only supplies vacuum above idle speeds, is it a "low vacuum" emissions port that supplies only a small amount of vacuum or is it simply a bowl vent that supplies no vacuum but only allows for collection of fuel vapors by the charcoal cansiter. You're gonna have to do some investigation.
Rochester built those carbs with zillions of different vacuum port configurations.
Is it full manifold vacuum at all times, is it a vacuum port that only supplies vacuum above idle speeds, is it a "low vacuum" emissions port that supplies only a small amount of vacuum or is it simply a bowl vent that supplies no vacuum but only allows for collection of fuel vapors by the charcoal cansiter. You're gonna have to do some investigation.
Rochester built those carbs with zillions of different vacuum port configurations.
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