Carb

JJ · Guru

Carb

68post · Poncho Master!

Verify that the secondary throttle blades are fully opening when you work the throttle, if they are, check the tension on your secondary air valve.
(Of course you've already checked that when you have the gas pedal to the floor, the throttle linkage at the carb is also wide open ?)

GLHS60 · Poncho Master!

There is a secondary lock out on the choke linkage side of the carb, that prevents the secondary's from opening while the choke is on. Have a close look at the choke/fast idle setup and you will see a small foot that blocks the secondary throttle shaft ( not the air valve on top) from opening when the choke is not fully off (open). With the engine off, and the throttle open about 1/2" if you open and close the choke you will see the fast idle and lock out in action, its a purely mechanical operation, visible to the naked eye.

A picture of your carb would help as some early and later Q jets sometimes had a slightly different setup.

Thanks
Randy

JJ · Guru

Here's a pic

-- Edited by JJ on Friday 27th of March 2015 06:31:29 PM

JJ · Guru

When I push the throttle they dont open thats for sure I will check more.

JJ · Guru

Its almost like the linkage is getting stuck there or the choke is not working properly. Could it be that I can tighten or loosen the spring on the choke?
Thx for all your guys help.

beaumontbob · Veteran Member

PM sent

67curves · Addicted!

JJ wrote:
Its almost like the linkage is getting stuck there or the choke is not working properly. Could it be that I can tighten or loosen the spring on the choke?
Thx for all your guys help.

I had one do that and the butterflys were catching on the base gasket.

GLHS60 · Poncho Master!

Don't touch the choke spring, but check the carb base gasket as mentioned. If it is a 1968 intake, the carb gasket should be a thin asbestos type with a very thin stainless shiny plate on top, next to the carb. They can not be run up side sown like many carb gaskets can, as there is a heat passage along the front but it is not uniform at the ends. Hopefully 427 Carl will come by and SCTV and rotate the pictures but it looks very tidy. Take it step by step and learn how every thing operates together.
A good working Q jet, choke, fast idle, curb idle performance and economy is the best carb made if everything is adjusted properly.

Thanks
Randy

-- Edited by GLHS60 on Sunday 29th of March 2015 12:31:10 AM

4SPEED427 · A Poncho Legend!

Your wish is my command Randy!

carb 2.jpg

JC2+2 · Poncho Master!

In the picture where you have your finger. Is that what you are concerned with? Those plates (air valve) will only open as air flows through. You'll never see those open right up on a free rev. If the secondary throttle plates are opening as Randy mentioned and the air valve can move freely with your finger as in the pictures then believe me they will open with air flow with the engine under load.

JJ · Guru

Thankyou guys for all the help. It looks like the little foot that stops it from opening is not releasing

-- Edited by JJ on Saturday 28th of March 2015 09:56:54 PM

GLHS60 · Poncho Master!

Good work finding the foot!!

Now you have to decide why its not releasing, remember to open the throttle approx. 1" while checking the choke, fast idle etc. and the little foot. With the throttle open, operate the choke closed and open and watch the fast idle cam swing and little foot should swing away from the secondary's, allowing them to open. Also when the choke is open also lift up on the arm that the choke rod attaches to and see if this will release the foot. If the foot still does not move check it to see if it is seized in place or not.

Sometimes the secondary throttle blades will get jammed shut and this will cause the secondary lever to hold the foot from moving.

And sometimes the top air valve gets jammed shut so check to see if it opens freely and if its spring slams it shut.

It looks like a nice unmolested carb other than the return spring so its worth figuring out whats up.

Thanks
Randy

427carl · A Poncho Legend!

Quadrajet Carb

427carl · A Poncho Legend!

RE: Carb

JJ · Guru

GLHS60 wrote:
Good work finding the foot!!

Now you have to decide why its not releasing, remember to open the throttle approx. 1" while checking the choke, fast idle etc. and the little foot. With the throttle open, operate the choke closed and open and watch the fast idle cam swing and little foot should swing away from the secondary's, allowing them to open. Also when the choke is open also lift up on the arm that the choke rod attaches to and see if this will release the foot. If the foot still does not move check it to see if it is seized in place or not.

Sometimes the secondary throttle blades will get jammed shut and this will cause the secondary lever to hold the foot from moving.

And sometimes the top air valve gets jammed shut so check to see if it opens freely and if its spring slams it shut.

It looks like a nice unmolested carb other than the return spring so its worth figuring out whats up.

Thanks
Randy

Thx Randy I will figure this out. Im going to print your post off while tinkering with the carb so im not running back and fourth.

GLHS60 · Poncho Master!

Any up dates JJ??

Thanks
Randy