Q-Jet secondaries not opening??? [Archive] - Team Camaro Tech

: Q-Jet secondaries not opening???


brucesay
Nov 27th, 99, 10:13 AM
I just did a rebuild on my Quadrajet and found a piece of plastic lodged in the carb that seemed to be preventing the secondaries from kicking in. ( I knew that it was lacking in power when kicking down), however, once we finished the rebuild and tuned the carb to specs, when I step on it the car really boggs down like it's not getting enough fuel to "feed" the secondaries. Please help!!!I want to go fast!

Rob.Canada
Nov 28th, 99, 12:46 PM
If you pump the gas several quick times then go wide open, does the bog seem to be less?
That piece of plastic where did you find it?
Answer back and we can try taking a guess.

brucesay
Nov 29th, 99, 03:50 PM
Well, I tried pumping the throttle a couple of times and then get on it and it still bogged the same amount as it had in the past. I've been reading up on the timing to see if that is a factor. It was at 10 BTDC and I dropped it down to 6 BTDC. I have read that it should be at 2 BTDC and also read that it should be at 4 BTDC. Either way, when I adjusted it down to 6 it really didn't help the "bogg".
About the plastic that was stuck in the carb. It was in the chamber that the metering rods for the secondaries are....underneath the tangs. ( Which was preventing the secondary flap from opening). It must have been a piece of the old air cleaner extension because when I bought the car, the one that was on there was broken in several places and the previous owner chose to try and glue it back together rather than spend $ 6.00 on a new one. It even had a rubberband around it holding it together when I bought it. (Amazing!!) SO....Here I am...hoping to find the "solution" to my problem!! Any help would be greatly appreciated!

mike brown
Dec 5th, 99, 02:48 PM
Must be the new R&B (rubber band) filtercharger, heard this was a new division of K&N. heheheh.

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BillK
Dec 5th, 99, 03:35 PM
Bruce,
If you have a bog, it is not because of insufficient fuel for the secondaries. On a 350 motor, the secondaries air valves probably don't even begin to open until around 3500 rpm. Look down in the carb while you move the throttle...does it pump fuel in the primaries immediately when you move the throttle ?? It should. If you have to pump it a couple of times to get fuel you have probably left out one of the accelerator pump check balls. If it is pumping right away, then your problem is elsewhere. You said you have the timing set at 6 BTDC...what distributor ? Is the vacuum advance working, not enough timing will also cause a bad hesitation. Send some more details about your combination and I will try to help.

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Bill Koustenis
Advanced Automotive Machine
Waldorf Md

68RS
Dec 5th, 99, 07:22 PM
Are the secondaries opening too fast? I have seen that as the most common bog problem with Q-jets. Also, there should be a small vaccume diaphram linked to the secondary air valve. Without it, the seconraries can open too fast. I would try to tighten up the air valve if it is loose. From what I remember, the best way to start tuning the air valve is to loosen them up until the valve begins to drop and then tighten the screw 3/4 or 7/8 of a turn. I think that is a good starting spot. It's been a while, anyone remember the proper procedure?

My homepage....
www.kdsi.net/~malandk (http://www.kdsi.net/~malandk)

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JimM
Dec 7th, 99, 01:00 PM
the procedure varies depending on the engine, specs are in the revuild kit instructions. Is the bog off idle, or at a higher rpm? part throtle or full? If you suspect the secondaries, a little fiddling with the lockout on the choke adjustment will stop them from opening at all, did the bog go away? sometimes Q-Jets leak fuel into the well in the middle. most rebuild kits include a piece to plug this. When I couldn't get my q-jet to work, I bought a Holley ProJection system. IT WORKS!!