Quadrajet 4MV

[slowboy]

Put remanufactured Quad 4MV on my '72 GMC 350. Choke plate would close for startup, then open slightly, like it was intended to do. Now choke plate has gotten where it won't close at startup, it sticks in open position. Now to start truck, I have to manually open throttle and push plate closed by hand before it'll start. Can someone tell me how to fix this choke plate problem...preferably not by buying different type of carburetor and using mine for a "boat anchor"? LOL ! !

[RustyParts]

I had one do that once, I had to remove the plate and file the outside edges to loosen it up.

[406 Q-ship]

How good is the thermo-coil on the intake? If it is weak it will not pull on the carb choke mech. hard enough, it might be more noticeable in warmer weather.

[geezer#99]

Take a pic for us before you start it of the side of the carb.

[Wrenchbender Ret]

Something is binding. The spring on the pulloff should snap it shut as soon as you open the throttle. It may be like Rusty says. The choke plates might be be rubbing. If not then the linkage is binding. You need a good choke thermostatic coil on that model. It has to get hot enough to overcome the sprint on the pulloff.

[GASoline71]

Originally Posted by 406 Q-ship

How good is the thermo-coil on the intake? If it is weak it will not pull on the carb choke mech. hard enough, it might be more noticeable in warmer weather.

Yep... had one on a '71 El Camino do the exact same thing. New thermo-coil thingy and it was fixed.

Gary

[geezer#99]

Apologies wrenchbender. You've got it backwards. Rod from thermo-coil pulls downward when cold which closes choke plate when you step on the pedal. When it starts vacuum pulls the choke open using the pulloff pot. Amount it opens is controlled by the bent arm hooked to the slot in the pulloff. When coil heats up rod pushes upward and when you tap the throttle it will kick off the high idle cam.
OP says it won't work unless used manually. I suspect thermo-coil or linkage rod popped off.
A pic will tell a thousand words.

[Wrenchbender Ret]

I dont have it backwards. On that model carb the spring on the pulloff helps close the choke untill the vacuum pulls it partway open like you said. The choke therm coil has to overcome the spring tension on the pulloff or the choke will reapply on full throttle when the vacuum is low. I have had to cut some coils out of the spring on some to get the right adjustment. I have worked on hundreds of them.

[slowboy]

I know I do need choke coil, rod, and cover/housing...can't seem to find where to buy these anywhere.

One other thing...shouldn't I be able to close choke plate manually from pull-off side of carb...can't do it there...just from top of carb [seems like I use to]?

[Wrenchbender Ret]

Yes you should be able to close it with the linkage but the throttle will have to be open a little to let the fast idle cam rise. If not you have something hanging or the linkage is going over center.

[oldgold70c10]

Originally Posted by slowboy

I know I do need choke coil, rod, and cover/housing...can't seem to find where to buy these anywhere.

One other thing...shouldn't I be able to close choke plate manually from pull-off side of carb...can't do it there...just from top of carb [seems like I use to]?

Edelbrock sells them.

[ARTISTIC]

I bought hard to find (read impossible) for Qjets here:

http://www.quadrajetparts.com/

You may have some luck or point you in the right direction.

I was at a wrecker today and even in this area found 5 - 10 Qjets of all kinds of configurations.

I had the same intake configuration on one of my old trucks and it was a pita to get working correctly - even worse when you convert to an aluminum intake without the recess.

My current carb has that exact setup with no intake choke spring or elec choke and it works fantastic. My problem was the lack of the spring on the vac takeoff. Bought the whole setup from the guys at the above link and problem solved!

[slowboy]

my previous quad I had on truck I ended up removing linkage and pulloff and running a cable from carb to inside of truck cab because of missing choke rod and housing...worked fine...I was hoping to find rod, housing and new coil and hooking this one up like it is meant to be...since I don't have original housing and rod, being the try anything I can think of type of person, I made a housing, and a rod out of a piece of coat hanger...yep...a piece of coat hanger...I know rod is, I believe, suppose to be 1/8" material, but didn't have anything that thick...choke plate was working as suppose to, for a while...I have noticed that the [I think it's called] the secondary lockout lever is just sorta 'dangling', and loose instead of sitting the way it should be

[oldgold70c10]

Is everything free with the carb off the engine? If yes, then from the photo, it looks like your coat-hanger choke rod may be able to jam in the slotted hole, locking everything up. You may want to adjust how you've got it bent so it can't jam. Also, is it long enough so that the coil on the manifold will open the choke?

[slowboy]

found original 1/8th inch rod for choke...will see what happens in the morning

[slowboy]

1/8th inch rod wasn't original, but after I took a picture of carb this morning, I saw that rod was too long, and hitting choke linkage at the top. This was preventing choke from closing. After modifying rod, [had to shorten it about 3/16ths of an inch] I noticed that choke still wasn't closing completely. Took choke coil and put it in freezer for 10 minutes, then put back on truck. Choke worked perfect, and truck fired right up. Probably work fine if it was winter time. I guess now the choke thermostat coil is going to have to be replaced. Must be wore out and lost some tension.
Checked with Eckler's, and can't believe they're wanting $25 for this thermostat. Anyone know of cheaper place to get one?
Might try junkyard. Don't know if I can find one, or the right one. Probably end up paying $25 anyways. Hope it's free shipping. Ain't a tightwad...on Social Security Disability and have limited income. Have to watch my pennies.

[slowboy]

Ok...bought new thermostat coil and put it on.
I've been trying to hook my divorce choke up on Qjet. It seems that if I make the rod that goes from thermostat coil to choke linkage short enough to close choke flap all the way, when engine warms up, the choke flap won't open all of the way. And vice-versa.
How do I fix this problem? I'm no expert on Qjets, and need help please.

Also...what are y'alls thoughts on using port behind choke pull off for vacuum advance?

[geezer#99]

Even though your home built coil cover looks nice maybe you need to install a factory one. JMHO

[slowboy]

where can I purchase this choke coil cover to fit my truck...

[GASoline71]

You can't... they aren't available.

But I have the factory cover and choke coil from my ol' '71 El Camino. Should be the same thing that came on the trucks. You can have it if you want it.

Send me a PM.

Gary

[406 Q-ship]

Edelbrock sells the coil, cover, and rod. I just put one on my 67 C10 that has an engine from a 1974 passenger car.

S/B Chevy Performer manifolds (Divorced Choke) 1931