Quadrajet Woes

[Linkman440]

So I have a quadrajet off of a 80s motor home with the 454. It has the electric choke and the vacuum pull off.

It’s driving me crazy. I’ve rebuilt it after it’s said for about 10 years. It was full of fire ants! But the issue is once I put it on the truck and start it up it idles way too high. Even after I backed the idle screw all the way out so it’s not even touching anymore.
I’m thinking that the throttle blades aren’t seating all the way. But I’m not sure. I can see light around them. And I don’t think I should be able to.

I can try to adjust the idle air screws all the way in or out and there is no change.

I can kill the motor if I manually push the choke closed and hold it there.
And if I put my hand over the carb it idles down. But runs rich I think.

I would appreciate any help here I can get!

[geezer#99]

Adjust the high idle screw.
It’s under the pull off.
Use a Phillips screwdriver to adjust with.

[Feel the 'Pane]

Originally Posted by geezer#99

Adjust the high idle screw.
It’s under the pull off.
Use a Phillips screwdriver to adjust with.

+1
And I always start with both idle mixture screws screwed all the way in & then backed out 1-3/4.

[Linkman440]

So I have the high idle screw backed all the way off and the idle mixture screws backed out to a turn and 3/4 and still the same issue of a super high idle.
I do appreciate all of the help and ideas!

[geezer#99]

when You rebuilt it, how far did you tear it apart?
Did you remove the throttle plates from the shaft?

[GASoline71]

Possibly a wicked vacuum leak some where.

Gary

[Linkman440]

I tore it completely apart. The throttle shafts we’re stuck so I removed the blades and soaked the rods in on blaster until I got them to free up and come out.
Question. The blades can go on either way correct?

I don’t think it’s a vacuum leak. I did spray around all vacuum connections and there was no change in the rpms.

[geezer#99]

Sounds like you got the blades/plates in a little off center.
What did you use for screws to mount them back to the shaft?

[Linkman440]

The heads snapped off of 2 of them so I drilled and tapped them to 4-40 screws. It is possible that I have them off center. I’ll pull it back apart this evening and check

[geezer#99]

That’s likely the culprit.
What have you done to make sure the screws don’t come loose and fall out?
They’re supposed to be staked into place.
You could of bought some replacements.
Like here. Two sizes.
https://quadrajetparts.com/quadrajet...-c-128_52.html

[Linkman440]

Ah. Then I’ll make sure to align them. I used red locktite on them. So they won’t go anywhere 😂

[geezer#99]

Another thing that can give you a problem with the plates is side to side movement of the shaft.

[Linkman440]

So I don’t have any side to side movement in the throttle shafts. And I’m pretty certain that I have the throttle blades centered up. But one thing I’ve noticed is that I can see light around the blades if I hold it up to the light.

[geezer#99]

You should be able to.
If you have the carb off take some pics of it.
Bottomside especially.

[Linkman440]

Here is the bottom. Is there anything in particular you would like you see?
And I have to say a big thank you for all the help so far!

[geezer#99]

When you put it back togethor take another pic of the bottom. I was wanting to see the transition slots in front of the primary plates.
And a pic of the choke side.
Not much light around the plates.

[Wrenchbender Ret]

The secondaries must seal tight. It looks like light coming in around the plates.

[Linkman440]

Ok. So I’ll be getting it back together this evening.
As for the light around the secondaries would it hurt if I took a dremel to the high spots until they seal completely?

[Linkman440]

Originally Posted by geezer#99

When you put it back togethor take another pic of the bottom. I was wanting to see the transition slots in front of the primary plates.
And a pic of the choke side.
Not much light around the plates.

Here are those photos. Let me know if you see anything or for you want to see something else!

[geezer#99]

Was hoping to see the transfer slots but can’t.
How much they’re covered will tell you if the primary plates are set right.
There’s a section in this link that talks about them so you can check. It’s a Holley but yours is the same.

http://www.crankshaftcoalition.com/w...EI_distributor

Looks like you got the plates closed off good.

What are you using for a carb to intake gasket?

[Linkman440]

I’m using a thick fel-pro gasket.

[cadillac_al]

Originally Posted by GASoline71

Possibly a wicked vacuum leak some where.

Gary

It would be nice to have another good working Qjet that you could try to make troubleshooting a lot easier. I think it's a vacuum leak too. It could be an internal vacuum leak in the Qjet. I would plug every vacuum port and put a gauge on it to see what's going on.

[Linkman440]

Originally Posted by cadillac_al

It would be nice to have another good working Qjet that you could try to make troubleshooting a lot easier. I think it's a vacuum leak too. It could be an internal vacuum leak in the Qjet. I would plug every vacuum port and put a gauge on it to see what's going on.

I do have another Q-jet. It’s not the same model. But it does work fine. I have tried blocking off all of the vacuum ports and it still does idle too high. I don’t have a gauge but I can get one and check it all out.

[geezer#99]

When you get it back on and running, post a few pics.
Front, back and choke side.
We might see something!

[jaros44sr]

Originally Posted by Linkman440

I tore it completely apart. The throttle shafts we’re stuck so I removed the blades and soaked the rods in on blaster until I got them to free up and come out.
Question. The blades can go on either way correct?

I don’t think it’s a vacuum leak. I did spray around all vacuum connections and there was no change in the rpms.

No, the blades only go in one way, there is a slight taper to the edges. And right to left makes a differance

could be why your seeing an air space around the blades