mayberg

Friends,

I'm wondering if I've done something bad to my Q-jet. After getting my carb back from tunedbylars.com, I was changing the vacuum hoses, including that dinky hose that goes from the front of the carb on the passenger side to the vacuum cannister that controls the secondaries (at least I think that's what it does). When pulling the hose, the fitting pulled out of the carb base.

I took a center punch and lightly tapped on the end to widen the fitting so it would press back in. I put it back in and tapped it down - hopefully all the way.

But with my fresh lars-bureator back on the car, the check ride was less than exciting. I'm wondering if I've dorked something up. The trans kick-down is just fine. I checked fuel, spark, timing, dwell, etc. before pulling the carb to send off. My vacuum reading is now in the normal range.

Should I be able to see the secondary throttle valves move while running the car? I goose the throttle, but I don't exactly go to WOT in the garage.

Let me know your thougths.

shoptek

Make sure your choke is opening 100%. There is a secondary lockout lever that stops the secs. from opening till the choke is 100% open.
Also, make sure that you are getting vac. to the pulloff you mentioned. That can be a factor.

shoptek

Also,
The top butterfly valve you see on the "air horn" is an air valve, the actual secondary throttle blades are in the base of the carb. This top air valve won't open much at all if you blip the throttle to WOT for a second or two.

Hope this helps!

Larry B.

You cannot make the air valve on top open unless there is a load on the engine. Sort of a demand system. The vacuum canisters you mention is called a choke pull off. It also acts as a dash pot to control the rate of secondary opening. It can be out of adjustment but I think Lars would have set it correctly. Make sure the throttle is opening to the stop on the card... do this from inside the car. The pedal and rod assembly bend over the years and the you don't get full throttle from the pedal. It is a common problem and hard to diagnose without two people.

mayberg

Thanks. How exactly would I check this?

mayberg

Thanks. I assume you mean "carb"?
How would I do this? Floor the pedal, then have someone check to make sure the throttle doesn't have farther to go on the carb?

Larry B.

Sorry about the typo... I did mean carB... What you want to do is have someone hold the gas pedal to the floor and make sure the tang on the primary linkage on the drivers side goes to the stop. (flange on the carb body)

shoptek

With the engine fully warmed up and running.....take the lid off the air cleaner and visually check that the choke butterfly is fully open. As Larry said....the vac pulloff works with it too!

mayberg

OK, this is done. The throttle linkage actually moves farther with the pedal than what I can move by hand.

lars

There is nothing that can prevent the secondaries from operating on a Q-Jet other than a choke that is not opening fully. You cannot get the secondary airvalve to open by "winging" the throttle in neutral - this is normal. The carb ran on the secondary side very nicely during my testing. If there is any issue with it, feel free to return it for re-testing and correcting once I return from Europe on the 23rd July.