80' vette, stock everything with quadra jet carb. Car runs and starts great. However, I exited the HWY and came to a light and the car was not wanting to slow down to easily so I put the car in neutral... 4.5k on the tach! I was only a mile away from my desitantion and was able to make it. What could have caused this and how to fix it? I want to go home tonight lol.

I hit the electronic choke with a screwdriver about 5-10 times and started the car and it idled normally. Then I gave it gas to see what happens and everything was fine. However, when I would go to WOT I noticed the reserve barrels are not even trying to open. What is suppose to make those open?

So, main question is.... Can a faulty choke allow the engine to rev that high? I have noticed the choke light come on and off here and there and the past few mornings the choke has not worked when the engine was cold.

Please help!

 

Did you spray the whole carb and lincage with some carb clean, and also some WD40 on all the lincage?

Also while you are under the hood, move the throttle cable and see if there is bind anywhere.

Is your carb return spring worn out???

Some things to check out.

 

It does sound like the choke's at fault.

I don't know quadrajets very well but I know that the choke locks out the reserve barrels when in the cold position.

It would also bring on the fast idle, that's the lug in the foreground of this pic.



The small phillips screw at the bottom of this pic is the fast idle adjustment screw. To get you home to sort it you could try winding this out, it should be out I think :o (remember how many turns so you can put it back).

 

That could answer why the reserve barrels don't open. I am sure the engine was warm enough because I drove 45miles non stop lol. I wonder if I can get that choke at the local parts store.

Also, I beat the choke a few times and the engine is not idling high now. So no need to adjust anything at this time


As for all the linkages and all that everything seems fine. Its not the links that seem to be the problem. Everything is smooth and springs work. Just the front two barrel stay open while reserve never open.

 

Don't forget that the secondary air valve (on top the carb) only opens with demand. Most people mistake the valve for the secondary throttle blades. You really can't get the air valve to open by revving the engine in neutral (no demand).

 

Have a pic of that? I am not afraid to say... I don't know what you are talking about? I am willing to learn!

 

If you loook carefully at the top pic in Golden's reply you will see a black gasket (like an o-ring) where the choke shaft passes into the body. Spraying with carb cleaner eventually causes it to deteriorate and bind and give an erratic / fast idle. A new one comes in a rebuild kit. It is easy to miss when overhauling the carb.

 

Check the carb return spring. I have seen the throttle cable cover cut through by the dist. shield & cause it to stick. If the cable gets at a bad angle it won't work right. Have you done anything to the carb or air filter recently? The El. choke can be adjusted so lean that it will stay open.

 

I have not touched the carb since I bought the car. Runs great for stock. Only thing I have done was tighten the fuel line a little. She still drips some fuel which I was going to address this weekend.

 

Can I not replace the choke on that carb? I went to the auto parts store and they don't even carry the choke.

 

My '77 and '74 Z28 have/had dual throttle cable springs, your '80 may/should have same. One outer spring and one inner spring that nest inside outer. Lack of proper throttle return springs will add a little excitement to your life in a hurry. Sticking or binding cable will do the same. If choke not working faulty linkage could bind throttle shaft also as others have suggested. Individual parts like choke are not available at any parts stores I have seen and are normally out of adjustment not necessarilly broken. Check springs, cable and linkage. You do not want this to reoccur. Repost results and guys will help. mds...

 

All links seem to work really well.No binding, grinding, tough feel... nothing. I took some pics tonight....



The rigged choke... could be why the choke light comes on while driving down the road?


What is this? Does it need to be fixed?

 

That broken Vacuum hose ftg is your thermal switch for your EGR, and yes if you have a functioning EGR you should replace it. The vacuum switch keeps the egr(exhaust gas recirculation) closed until the engine warms up then allows some exhaust gases into the hot motor, which actually can help increase the "octane" rating of the fuel by helping to retard the explosion. It sounds good in theroy but most people take it off as they can be difficult to keep working properly, and when they don't work right it actually makes your engine run worse.
Also check your choke pull off cansiter, they can stick or go bad.

 

Ok, so far all it good but I don't trust it lol

New question. I have looked at the recipts that was given to me with the car for the last two years. Well, the carb has been replaced 3 times. 1st was new reman q-jet, 2st was rebuilt qjet, 3nd was attempted rebuild but replaced with with a reman. q-jet. So, I am thinking of getting rid of it all and go for new. Thinking edelbrock but I am not sure what CFM carb to get. Everything is stock. 650 or 750? I read q-jets are 750-800. This is my daily driver so I want the best all around setup. I will also replace the intake at the same time.

 

Holley has a Q-J spreadbore 650 replacement carb. If you change intakes the Performer will allow both spreadbore & square bore carbs. 600-650 will do it for you.

SEE CARBS Tests TQ/HP
http://www.corvettefaq.com/c3/carbcomparo.htm

 

If the carb was replaced/repaired 3 times in order to solve a problem, chances are it wasn't the carb which was at fault. So, while the carb looks like it has some age/wear on it, replacing it again may be a waste of time & money. I would suggest that you do a few things first...and then see how it operates.
1) Replace the temp sensor at the water inlet housing. The upper fitting is broken off, which means the hose that was there is leaking vacuum. Pull the broken piece out of the hose, install a new temp sensor (lectriclimited.com has the correct one, I believe; the "Zone" and other such places won't have it), 2) Remove the choke mechanism from the carb, disassemble & clean it; repair the damaged wiring/connector which goes to it. Also clean up the fast idle mechanism/parts (behind the choke) and make sure it operates freely. 3) Then, remove the EGR valve from the intake manifold and clean it all up. Since the vacuum line has been missing from the temp sensor, the EGR has not been functioning. Thus, it is probably carboned-up and stuck in position. Test the cleaned-up valve with suction to see if it moves freely. If so, stick it back on; if not, replace it. 4) Now set the choke up according to the Chevy Chassis Service Manual instructions. If you don't have a copy, ask on this Forum for the instructions from someone who does have one for your year car. 5) Since that vacuum line was 'off', your carb idle mixture, fast idle setting and idle speed adjustments need to be redone. That is in the Chassis Service Manual, also. {You really should get one, if you don't have it already.}

It sounds like a lot of stuff to do, but none of it is very difficult and ALL of that needs to be done before you have any hope of solving [or diagnosing] your problem. I'd bet money that your problem will be gone when you finish that work. Good luck; and let us know how it went.

 

Sounds like you have not yet diagnosed exactly what's wrong. Throwing money at 'guesses' rarely works.

 

Thanks for the info.. I will try that this weekend.

Also.... I plugged the vacuum line with a screw when it broke off. How do you know if the EGR valve works? Plus, there are two letters on the temp sensor.. C & I think a V.. I can't remember I would have to look again. Anyways, I would assume the C means carb and the other means the EGR valve. Well, the carb is plugged into the top and the EGR on the bottom. Is that right?

I just got my shop manual in on CD and will look at it this weekend when I have a chance.

 

Understandable... Sometimes I rather throw money at it because I don't have the time to tinker with the car. I work full time and go to school full time. Finals are this coming week and the week after and I don't have time for the car to break down. It would not be that bad but my other daily drive broke down too. Stupid fuel pump! I have to solder the wires in the fuel tank... what kind of crap is that!

Anyways, I will try 7t1vette suggestion first and post back. I won't work on it until Sunday.

Thank you everyone!

 

You referred to them as reserve barrels. The air valve is the two big springloaded doors on the secondary side of the carburetor. When you look down at the carb, the choke flap is on the primary side, the air valve is on the secondary side. The actually throttle blades are located on the bottom of the carb.