Cliff's Quadrajet Parts and Rebuild Kits

Quadrajet Problem Solving => Diagnose a Quadrajet carburetor problem => Topic started by: larryneworleans on March 28, 2013, 12:36:46 PM

Title: what does this spring do
Post by: larryneworleans on March 28, 2013, 12:36:46 PM

I ordered a new air valve shaft and it is different from my original.
My original has a spring loaded cam/arm at the end.
The replacement does  not, although it appears to be compatible.

I have attached an example of what the original looked like.

It looks like this spring was for older quadrajets.

Title: Re: what does this spring do
Post by: Ethan1 on March 28, 2013, 12:54:46 PM

 Not sure. Do you have a pic of the spring you have now?

Title: Re: what does this spring do
Post by: larryneworleans on March 28, 2013, 12:55:58 PM

This is a picture of what the original looked like before I removed it

Title: Re: what does this spring do
Post by: larryneworleans on March 28, 2013, 01:01:35 PM

here is another example of what the original looked like approximately
the replacement (not pictured) does not have this outer spring

Title: Re: what does this spring do
Post by: Shark Racer on March 28, 2013, 03:18:10 PM

I'm confused. The photos are of the secondary throttle shaft. The air valve shaft is on top of the carburetor behind the choke horn.

Title: Re: what does this spring do
Post by: Ethan1 on March 28, 2013, 04:04:18 PM

Quote from: Shark Racer on March 28, 2013, 03:18:10 PM

I'm confused. The photos are of the secondary throttle shaft. The air valve shaft is on top of the carburetor behind the choke horn.

 Same here. The air valve shaft is on the top of the carburetor. The spring(s) you are showing are part of the secondary throttle shaft. The last picture you have is what it should look like. ???

Title: Re: what does this spring do
Post by: Ethan1 on March 28, 2013, 04:05:56 PM

 Show us a photo of the spring you are confused about.

Title: OOPS what does this spring do
Post by: larryneworleans on March 29, 2013, 07:01:40 AM

OOPs it is on the  secondary throttle shaft.
I picked the wrong name off of the exploded diagram. The spring and cam in on the outside of the secondary shaft.

On my original  the primary and secondary  open with a direct connection via  secondary valve actuating rod pushing on the the secondary throttle lever .

However when the primary closes   secondary valve actuating rod  pulls the secondary closed via this springloaded cam on the out side of the secondary throttle shaft

On the replacement seconday shaft  there is no outer cam or spring, the primary and secondary are connect only thru the secondary valve actuating rod direrctly.

I have outlined in red the outer spring and cam

Title: Re: what does this spring do
Post by: Shark Racer on March 29, 2013, 08:06:10 AM

That spring is there on carbs that have a secondary lockout behind the choke. It allows the primary linkage to go WOT while the secondaries are locked.

Some earlier carbs do not have the secondary lockout.

I noticed on this 7044276 carb I've been working on that the air valves are lockable instead of the throttle blades.


Picture of carb with no secondary throttle blade lockout:
(http://i.ebayimg.com/t/rochester-4bbl-quadrajet-7044276-1974-pontiac-400-455-date-1294-/00/s/MTIwMFgxNjAw/$(KGrHqV,!qEE-vinqovEBP5SFqFzyg~~60_12.JPG)

Title: Re: what does this spring do
Post by: Ethan1 on March 29, 2013, 03:31:55 PM

 Ok, I see now. By chance, what is the carb number?

Title: Re: what does this spring do
Post by: larryneworleans on April 01, 2013, 07:47:38 AM

it is a 7029268 and the  secondary lockout was there but was removed by the previous owner

Title: Re: what does this spring do
Post by: Cliff Ruggles on April 03, 2013, 05:07:56 AM

Carb number 7029268 only uses the inner spring, lock-out is in the airhorn.....Cliff