1986 Q-Jet Carb. Adjustments?

[kustomkyle]

I was wondering how adjustments are to be made on the newer computer controlled Rochester Quadrajets. The choke is sealed, the mixture screws are sealed, etc., etc. The idle is adjustable though. I'm mostly concerned with how you adjust the mixture. It's not like a newer car that you adjust everything with a laptop, so what do you do? The Chilton's manual on 1973-1987 Buick Regal/Century has nothing on carburetor adjustments.

The carb. is on a 1986 Oldsmobile 307, manufactured in 1985, but that shouldn't really matter, right? The computer control came in 1981 if I'm not mistaken.

 

[joe_padavano]

I was wondering how adjustments are to be made on the newer computer controlled Rochester Quadrajets. The choke is sealed, the mixture screws are sealed, etc., etc. The idle is adjustable though. I'm mostly concerned with how you adjust the mixture. It's not like a newer car that you adjust everything with a laptop, so what do you do? The Chilton's manual on 1973-1987 Buick Regal/Century has nothing on carburetor adjustments.

The carb. is on a 1986 Oldsmobile 307, manufactured in 1985, but that shouldn't really matter, right? The computer control came in 1981 if I'm not mistaken.

First, throw away the Chiltons and get a correct factory service manual for your car. The CCC system on the 307 is very sensitive to adjustment and the process must be followed exactly. The Chassis Service Manual spells this out in extreme detail. It's too long to list here.

 

[megaladon6]

techinicall all q-jets had sealed chokes and idle mixture adjustments. you may have to pull the carb to make it easier, but pulling the seals is easy enough. actually it's pretty rare to find one that still has the seals intact. as stated, make sure you have a good procedure when adjusting and testing a CCC carb.

 

[kustomkyle]

I've been meaning to get a GM service manual of some sort for a while, but I've only ever found a "body service manual" for 1986 GM cars, which are a dime a dozen, and kind of useless. Would the tuning information be different from year to year in the chassis manuals (1981-1988)? They have been hard to find for me.

There is a 1986 Buick Chassis Service Manual I found for sale, but it is volume 2 of 2, and the description says that it is basically wiring, etc. Does anyone know if the info I need is in volume 1 or 2? Thanks.

I didn't know all Quadrajets were sealed up like mine. It sort of makes sense on the newer ones since the computer is supposed to control stuff, but the older ones too (pre-EGR)?

 

[kustomkyle]

Currently searching for a decently priced manual/s.

In the mean time, are timing adjustments just as sensitive as the carb.?

I'm trying to eliminate spark knock, and the timing/fuel mixture seems to be what controls that. The EGR valve wasn't stuck or clogged when it was checked a while ago, but could the EGR solenoid (or whatever controls the EGR) be a possible culprit? The oxygen sensor was replaced a while ago, but I've heard oil additives (STP, CD2, etc.) can ruin it and make the car run lean as well if the oil gets burnt. Does anyone know anything about that?