rochester quadrajet carburetor secondaries

[forestb]

I have a rochester quadrajet carburetor on my 350 and am concerned that my secondaries are not opening. I was wondering what the best way is to check if they are.

[crazy longhorn]

Its been a while, but I will take a stab @ it? If the choke does not open all the way, the lockout will not let the seconds open (for cold use). There is an air door on top of the Qjet(seconds), that opens on demand. What I would do to check, would be to take the air cleaner off(not running)....open the choke & the air door, then open the throttle. If you look down the seconds, look to see if they are open. It could be as simple as a throttle cable adjustment, that does not give you full throttle I will turn this back, for the rest of the truck mnuts to post /play longhorn

[MySons68C20]

They're vacuum operated and won't work with the engine off or not under load.

[burnin oil]

Longhorns is right. They are a mechanical secondary setup. The kicker is the air door up top that looks like a choke. That is what keeps them from functioning until demand is needed.

[MySons68C20]

I got the vac doors confused with the actual secondaries....my bad

[geezer#99]

You don’t need to hold the vac door open and stroke the throttle.
Just check the lock out tang on the choke side.
If it’s engaged then no secondaries.
If it stays engaged when completely warmed up then a choke adjustment is needed.

[crazy longhorn]

[QUOTE=geezer#99;8662704]You don’t need to hold the vac door open and stroke the throttle.
Just check the lock out tang on the choke side.
If it’s engaged then no secondaries.
If it stays engaged when completely warmed up then a choke adjustment is needed.[/QUOTE From one geezer to another, I would still check both deals.....how many times have we missed a tenth or 2 on the drag strip, because the adjustment was off on the throttle cable? No argue...shorthorn

[ron350]

Forestb can you please post a picture of your carburetor taken from the passenger’s side.

It is difficult to talk about a Quadrajet without pictures.

[forestb]

Will do when I get a chance. Not feeling well right now so it might be a couple of days.

[burnin oil]

[/QUOTE From one geezer to another, I would still check both deals.....how many times have we missed a tenth or 2 on the drag strip, because the adjustment was off on the throttle cable? No argue...shorthorn[/QUOTE]

That happened on a buddy's mustang. He swapped a 4 barrel on and reused the 2 barrel throttle cable. His eighth mile was in the minutes when it snapped and he coasted down the track. We spliced it back together for the ride home. Cruise was nice since it now idled at 3500RPM!

[forestb]

Photos of both sides. I checked and I am getting full throttle from the peddle so I don’t think it’s a throttle cable problem.

[forestb]

One more

[ron350]

OK in the picture the yellow arrow is pointing at the secondary throttle shaft with a horizontal slot in it. When you open the throttle fully that slot should rotate clockwise about 90 degrees. If that shaft does not rotate your secondaries are not opening probably because the lock out lever on the choke assembly is engaged.

[ron350]

Looking at this picture from the passengers side the lock out lever (in yellow) has the secondaries locked out. When the choke opens the lever is supposed to swing down away from the pin in the secondary shaft.

[forestb]

Originally Posted by ron350

OK in the picture the yellow arrow is pointing at the secondary throttle shaft with a horizontal slot in it. When you open the throttle fully that slot should rotate clockwise about 90 degrees. If that shaft does not rotate your secondaries are not opening probably because the lock out lever on the choke assembly is engaged.

I am assuming that I should check this with the motor warm

[ron350]

Yes with a warm motor or with a warm electric choke.

[forestb]

So I let it worm up to around 120 degrees, I turned it off and turned the throttle and the little slot didn’t rotate at all and the little lever (in yellow) did not move away from the post on the secondary shaft. I turned it back on and still nothing. I checked the wire that goes to the choke and it has power when the engine is running.

[forestb]

Should this port with the blue cap on it be connected to anything

[ron350]

That blue port would be used if you had the stock choke assembly. It would connect to the hot air stove mounted in the intake manifold.

Your next step is to make sure your electric choke is working.
Put a paint dot or a scratch on the plastic electric choke where I have a yellow arrow pointing so you can put it back where it was.
Then remove the 3 screws holding the electric choke to the housing and slowly pull out the choke. You want to see if the arm on the electric choke is in the slot in the choke assembly.

When you have the electric choke out you can place it coil side up on a thick towel or rag to make sure it does not short to ground. You will have to connect a jumper wire to the ground on the edge of the electric choke to complete the circuit to see if the choke colil works.

Some one running an electric choke please jump in here and help.

[ron350]

Once you apply 12 volts to the electric choke the bimetal coil should turn counter counterclockwise.

[forestb]

So just to get this straight. I connect a ground to the flat disc and 12 volts to the plug and the pigtail end of the coil should turn counter clockwise?

Just a thought. Because I have an aluminum intake manifold could it be possible that my choke is not getting a good ground?

[ron350]

Yes it should turn counter-clockwise.
You should have 12 volts + to the red wire on the electric choke when the ignition switch is turned to the RUN position.

Aluminum is very conductive your hold down bolts should supply ground for the intake and carb.

[forestb]

Okay thanks

[geezer#99]

Before you pull it apart just compress the choke pull off plunger all the way and see if the lock out tang drops out of the way.

I’ve seen the wrong sealing gasket used on the electric choke when converted from a hot air type. Hot air uses a plastic seal ring. Electric needs a metal one for a good ground.

[forestb]

Originally Posted by geezer#99

Before you pull it apart just compress the choke pull off plunger all the way and see if the lock out tang drops out of the way.

I’ve seen the wrong sealing gasket used on the electric choke when converted from a hot air type. Hot air uses a plastic seal ring. Electric needs a metal one for a good ground.

If it does fall away when I compress it then I need to check the choke? It it doesn’t fall away what does that mean?