Holy Smoke, Batman

[CS72Roadster]

After reading some posts and other articles on tuning the Q-Jet; I began tinkering with mine. It is in need of a rebuild and that will be forth-coming soon. Night before last, I discovered that the secondaries were hardly openning even under full throttle on my base 200hp 350. Within a few minutes I had those babies openning up. Yesterday's drive to work proved to be like driving a new car. Well, last night I adjusted the air valves on the secondaries and have them openning up much quicker, a little to quick right now, but MAN it is like I dropped a new engine in the car!

Holy smoke! I can't keep my foot out of it now.

CS

 

[78SilvAnniv]

Oh yeah!

That was my problem, too.

We rebuilt the carb and adjusted the secondaries, then shortly after that had chambered exhaust installed. Double trouble! I can't keep my foot out of it because of the double effect of response and noise!

Watch your gas mileage suffer. Mine does.
Heidi

 

[CS72Roadster]

"Gas mileage"; what's that? :confused

CS

 

[Bob Chadwick]

CS,

Can you post what you did to adjust these two items?

Bob

 

[81 Corvette]

Sweet. I can't wait to bolt up my Road Deamon and play with it.

 

[CS72Roadster]

Yes, I can with some reluctency. The adjustment to the secondaries is probably not the correct way since Bubba had "fixed" it previously, however it works...for now. The linkage from the primaries to the secondaries had apparently broken and been replaced with homemade linkage. I further Bubba'd it by making a new linkage, only slightly longer to open the secondaries just about all the way under full throttle. Initially, they would only partially open. As far as the AV flap; on the passenger side of the carb is an allen head set screw in a verticle position and an adjustment screw the sets the spring tension on the AV flaps. It right there by the end of the AV flap shaft. Loosen the set screw and then turn the adj screw CCW to loosen spring tension. If you "set" it too loose the engine will bog under heavy acceleration, but play with it until you get it just right. Mine is just a tad too loose right now and has a slight bog if I stomp it, but I'll fix that this evening.

I hope this helps and I'm sure there are others here who can better explain this procedure. If I have used incorrect terminology on the carb parts, feel free to correct me.

CS

 

[Bob Chadwick]

Thanks CS.

I've been looking at the instructions on the AV valve but didn't know we were talking about the same thing. I have the infamous "quadra-bog" and have been looking at this as well jsut haven't had the time.

Bob

 

[CS72Roadster]

bobchad,

It is very possible that by increasing the spring tension; you can solve your bog problem. The increased spring tension will delay the AV flaps opening, reducing the initial fuel mixture volume from the secondaries and should allow the engine rev up without bogging.

CS

 

[Bob Chadwick]

That's my hope. I've added true duals, distributor recurve and a performer intake and really don't notice any increase in performance. I have an appointment on 9/5 to have the carb gone over but if it is something as simple as this I'm hoping to take care of it myself.