Carb issues with secondaries

[IndifferentJester]

Hey guys, recently replaced/cleaned bits and pieces in my carburetor due to sticking and leaking issues (which is now fixed). The only issue I haven't been able to solve is my secondaries not engaging due to my secondary-lockout-lever being engage. The only way it becomes free is if I jerk/slam to WOT. If I try gradual/slow throttle to WOT it still locked.

To better illustrate I give you my amazing paint workmanship.


Granted I know there also vacuum to account for so I did this as well.


The orange is where the fast idle stops when WOT and also vaccum included. I feel like it should be bottomed out at the red arrow, cause that's when it disengages the lockout, but it only goes there with my finger.

Thanks for the help and does anyone know the fuel line end sizes for the carburetor to fuel pump for 72 C10 350?

[geezer#99]

It's a choke pull off problem.
That bent rod by your finger in the second pick pulls the choke open fully (and releases the tang) when the pot is pulled all the way in. Yours isn't. To fix just put a bit more bend in the rod.

[slikside]

Originally Posted by geezer#99

It's a choke pull off problem.
That bent rod by your finger in the second pick pulls the choke open fully (and releases the tang) when the pot is pulled all the way in. Yours isn't. To fix just put a bit more bend in the rod.

Hey geezer, is it the choke pull-off mechanism, or the linkage to the choke plate itself? IIRC, that lockout for the secondaries is linked to the choke rod itself, and as the choke gradually moves fully open as the engine warms up, that lockout is moved gradually as well. Makes sense cuz the lockout is there to prevent the secondaries from opening until the engine is sufficiently heated up. At least that's how it works on my q-jet with divorced choke.

[rx78nt1alex]

3/8" tubing with this 45 degree inverted flare fitting from NAPA
BK 6413336
http://www.napaonline.com/Catalog/Ca...336_0361071957

Call them first thing in the morning, they'll usually get it in by 5 pm same day from the warehouse.

It is 3/8" tubing with same fitting on both ends.

[slikside]

IJ,

I don't think you will get the lockout to move just "dry testing" the carb like you are in the pics without the choke hooked up.

In my case (divorced choke) that lockout doesn't clear until the engine is warmed up. The choke pull-off just cracks the choke plate open a bit immediately after the engine fires, to keep it running. But it is the divorced choke expansion spring, through that cam, to the choke plate linkage, that moves the lockout out of the way as the engine warms, and the choke is fully open.

In other words, the choke pull-off feature, and the secondary lock-out mechanism operate separately, even though both are connected to that same cam.

That's how it all works on my rig anyway.

[mechanicalman]

3/8" fuel pipe, you can go to the u-pull-it and pick out a nice one that will clear your accessories (the easy way).

Or you can buy a pre-made section of double flared 3/8 line, bend to fit and cut/re-flare to length (the hard way).

Resist the urge to use hose from the pump to the carb, the filter in the carb itself is all you need. If your filter retention spring is gone, get one at the u-pull-it or from this outfit:
http://www.carburetion.com/quadrajet.asp

Remember the choke has to open for the secondaries to un-lock. Try installing the choke rod and push it upward like the choke is opening, the secondaries should un-lock. If not, re-trace your steps and re-assemble the choke linkages. Stock base gasket has to be used for the divorced choke to operate properly.
https://www.rockauto.com/catalog/mor...nid=532&jpid=4
https://www.rockauto.com/catalog/mor...nid=532&jpid=5
Good luck

Going to the junk yard is fun!

[mechanicalman]

https://www.google.com/search?q=divo...w&ved=0CB0QsAQ

[mechanicalman]

Also the pin in the secondary shaft may be protruding too far. You can adjust it a little with a pair of dull side-cutters just pull it back a smidge, maybe it's just binding.

[slikside]

Looks like mechanicalman posted a bunch of pics with a choke hooked up. If one of those doesn't work, I might have some closeups on another computer I could post from when I rebuilt mine.

[Mr Handy]

Yup as others said the choke is what is supposed to control the secondary lockout.
I just installed an electric choke on mine. I went out and took a couple pics... First is with the choke in cold position.
Second is where the choke pushes the cam up to unlock the secondaries.
This keeps the secondaries locked until up to temp.

[mechanicalman]

Originally Posted by Mr Handy

Yup as others said the choke is what is supposed to control the secondary lockout.
I just installed an electric choke on mine. I went out and took a couple pics... First is with the choke in cold position.
Second is where the choke pushes the cam up to unlock the secondaries.
This keeps the secondaries locked until up to temp.

Nice looking set-up, let us know how well it works out for you. I just bought I think the same spacer for mine, it's a Mr. Gasket. I don't see any other way you could have made the choke work with the spacer, especially on the Edelbrock manifold without a major hassle; nice.

[IndifferentJester]

Appreciate all the help guys. In regards to my fuel line they seem to be different sizes (guess that's why the PO had a rubber hose near the carb). Seems like the carb is 1/2" while the fuel pump is 3/8" (guessing). Noticed this while I was attempting to install the new fuel line into the pump and it was too large. Is this normal and how can I remedy the two different sizes?

Also due to my lack of knowledge and your guys help I've noticed something.


Anyone notice anything missing? Seem I don't have a divorce choke to go to. Can I throw any choke I find at the junkyard in here?

[geezer#99]

Originally Posted by IndifferentJester

Appreciate all the help guys. In regards to my fuel line they seem to be different sizes (guess that's why the PO had a rubber hose near the carb). Seems like the carb is 1/2" while the fuel pump is 3/8" (guessing). Noticed this while I was attempting to install the new fuel line into the pump and it was too large. Is this normal and how can I remedy the two different sizes?

Also due to my lack of knowledge and your guys help I've noticed something.
Attachment 1398408

Anyone notice anything missing? Seem I don't have a divorce choke to go to. Can I throw any choke I find at the junkyard in here?

Look here for choke stoves.
http://quadrajetparts.com/rochester-...-c-128_23.html

[Bigdav160]

Something doesn't look right with the cam on the throttle shaft

[slikside]

And take a look at Mr. Handy's fuel line fittings at the carb. Your fitting does not appear to be stock, but you should be able to find another one to adapt from what you have at the carb, to the line.

And yeah, if you can find a divorced choke at the yard, I dont see why you couldn't install it. If electric, unless you can test it somehow, may or may not work...

[Wrenchbender Ret]

The choke heat coil is supposed to over ride the spring on the pulloff. Often they don't. I have cut a few coils out of the spring on the pulloff many times to solve this. The choke must open fully to disengauge the lockout.

[IndifferentJester]

Sadly no luck at the junkyard, they used to have 2 C10's (or even similar trucks of the time) but I guess they scrapped em.

Originally Posted by Bigdav160

Something doesn't look right with the cam on the throttle shaft

What do you mean?

Thanks Mr. Handy and Geezer.

Originally Posted by Wrenchbender Ret

The choke heat coil is supposed to over ride the spring on the pulloff. Often they don't. I have cut a few coils out of the spring on the pulloff many times to solve this. The choke must open fully to disengauge the lockout.

Not entirely sure what you mean. I'm still learning what the parts are called and more so a visual learner as well.

Also, is the cam - fast idle suppose to be loose? I understand the screw to adjust the tension depending upon what idle increment you want but there's really nothing making it go down towards the engine block except gravity. If it helps the casting number on it is 7041209.

Thanks again dealing with my inexperience. Also posted some close ups below just to see if I put it back together.

[Wrenchbender Ret]

Your main problem is you don't have a choke coil on it according to the photos. There should be a pot metal piece with a thermo coil & a cover. It goes on the plateform on the intake with a screw that holds it down. It has a rod that goes up to the sloted hole in the lever. Like Handy shows in his photo. His coil has been replaced by a electric choke conversion kit. I don't know if that is still available. I like to find late 70's early 80's Q-jets with the electric choke, if you are not concerned about #'s matching.
Ive never seen one with that larger tube size. The fitting from another carb will replace it with 3/8 size.

[IndifferentJester]

Mr. Handy, where did your wiring for the electronic choke go to? If I were to buy a divorce choke, rod, and cover seems to come out the same price (since I cant find one at the pickapart).

[slikside]

IJ,

Yep, fast idle cam should be loose....no friction. It's mounted off-center to move on gravity force only.

I think that whole section of your carb looks properly set up...you just need the choke.

[IndifferentJester]

Alright gents, took me longer to do what was needed. I found out the fuel pump end was actually 1/4" output which is why my fuel line wasn't fitting and also realized that the PO had a 1/4" coming out, then rubber hose, connected to a 3/8" hose to the carb. I just went to autozone and spent $20 for a new one and solved my issue, so I got my new fuel line in without issues. Alas I have run into another problem. I can't seem to get my divorced choke to stay put, it's not really secured to anything but seems to sit on top of the manifold. The damn thing immediately gets dismounted once the vacuum moves the vacuum bracket. Suggestions?




Also, how long should the coil take to unwind to move the secondary. I left it running for quite some time and drove it around but it didn't seem to budge even though I knew the engine was hot, even with it being 80F outside. Thanks for your input.

*Should have mentioned that there isn't a threaded hole for a screw*

[mechanicalman]

Originally Posted by IndifferentJester

I can't seem to get my divorced choke to stay put, it's not really secured to anything but seems to sit on top of the manifold. The damn thing immediately gets dismounted once the vacuum moves the vacuum bracket. Suggestions?

Also, how long should the coil take to unwind to move the secondary. I left it running for quite some time and drove it around but it didn't seem to budge even though I knew the engine was hot, even with it being 80F outside. Thanks for your input.

*Should have mentioned that there isn't a threaded hole for a screw*

The choke will never heat up if it's not bolted down securely to the flat spot on the manifold.

Clean the flat spot on the manifold, drill/tap the area for the hole, bolt it down and try again.

Also, the thickness of the carb gasket comes into play, if it's a new choke then you need an OEM equivalent thickness gasket for starters if you don't have one already.

The application for the choke stove/coil, linkage rod need to match the application for the gasket. Some years had a "sandwich" gasket with a thin metal center, not sure if they are the same thickness.

[IndifferentJester]

Will try Mech. The gasket I'm using came in the rebuild kit I got from quadrajet, seems to be a 1/4" thick (between the manifold and carb) off the top of my head and was identical to the one that was previously on there. Will let you know how it goes.

[mechanicalman]

Originally Posted by IndifferentJester

Will try Mech. The gasket I'm using came in the rebuild kit I got from quadrajet, seems to be a 1/4" thick (between the manifold and carb) off the top of my head and was identical to the one that was previously on there. Will let you know how it goes.

You gasket is probably OK, just something to consider vs the choke coil/stove application.

When dealing with unknown factors, it's best to have everything from the same application.

[geezer#99]

If you need to make a custom length linkage rod use an old wire coathanger to make one.
And JFYI don't use teflon tape on flare fittings. The seal is on the flare, not on the threads.