Quadrajet help needed

[Jayy]

Hello! First time here, so glad to have found this forum! I am a long time Chevy guy. I drive a 71 Nova. Writing here about my Fathers 79 Silverado which was given to him about 10 years ago and it has sat a while, started up every month or so. Now we are looking to get it on the road. It has a 350 and runs good after it is warmed up. The problem is a lot of engine revs before starting up (about 8 or so). I am sure there are issues with the choke. Also, not sure the secondaries are opening. can not be sure but I see no mechanical way of them opening since the vacuum plunger seems to be maxxed out. I could be wrong. Also, there are a lot of plugged vacuum ports and this seems to have EGR.

Looking for some advice on where to start. Or would it be easier to pull this and replace or have rebuilt? My initial thought is that perhaps there is a simple fix by getting the vacuum ports sorted out. Pics of what I we have and thanks in advance for any tips.
Jay

You must be registered for see images attach

You must be registered for see images attach

 

[Jayy]

Sorry for large pics, just figuring this out...

You must be registered for see images attach

 

[Blue Ox]

Is there an emissions tag on the rad support or thereabouts? That would have the hose routing diagram on it.

 

[Bextreme04]

First of all, welcome!

Secondly, what is the actual problem you are trying to solve? It looks like you have a C/K10 here? I have an 80 K25 and it doesn't have EGR, due to being over the emissions GVWR.

The plugged port on the carburetor would normally run to the thermostatically controlled vacuum switch near the thermostat housing and then from there to the EGR. The second vaccuum switch next to it is for the vacuum advance on the distributor. Those switches keep the EGR and distributor advance from functioning when the engine is cold. They fail pretty regularly and are expensive and not really necessary, so most people just by-pass them.

In order to start your truck when cold, you need to press the gas pedal all the way to the floor and slowly let it up before cranking. That sets the carburetor onto the fast idle cam and squirts a bit of gas into the intake through the accelerator pump. If it is colder outside, you might want to give it two or three pumps. It should then crank a few times and then fire up into the high idle. The vacuum cylinder on the front of the carburetor is the choke pull-off, if it isn't starting when on the high-idle cam it is often due to a bad choke pull-off. You should see that rod pull in and open the choke just a little bit when the engine starts to crank.

The secondaries will be manually locked out until the engine warms up and the choke is off. The flaps over the secondaries you can see in the pictures are not the actual secondaries. They should be able to be pushed open with a little bit of resistance from the spring tension on them. If they just drop open and stay there when you push on them or don't snap back, you have a broken, worn, or out of adjustment tension spring and will need to address that. If you don't fix that tension, you will get a massive bog down when you go full throttle and the secondaries open.

The secondaries are under that flap on top and will only open when the engine is warm and the throttle is opened over about 3/4. You'll feel the extra tension from pulling the secondaries open when you manually pull the throttle all the way to the stops.

 

[Jayy]

Thanks, I will review all of this a couple times and then go check things out, including looking for that hose diagram. Appreciate the reply!

Problem: Sorry I was not clear. It could be a warm day or any time of year.... the engine starts and choke does not come down / idles very high. I would expect to mash the pedal and being able to idle down, that does not happen for at least 8-10 minutes. That is the problem I am trying to solve.