A Discussion About The Choke on a Four Barrel Rochester Carburetor 

Your choke and fast idle cam is working right. The proper starting procedures for that type carburetor on gm cars from the manuals, was to at least push the accelerator pedal to the floor once or twice if necessary. But any of them once these cars were five years old on average required 5 times to the floor when they were cold. But even with your choke operating good,they wont start if your accelerator pump is bad

thanks for the info ! this is going to help me adjust my 1984 C10 which has given me nightmares. love your videos !

Very informative video . Thanks for sharing your knowledge and experience Blessings and more blessings to you and your family

on mine, the electric connection to the choke thermostatic spring often gets bad and needs cleaning. That causes the choke to not open, or open slowly. Also watching this, I realized my "heat riser" is missing. I never knew what that was and didn't think it was important! hahaha thanks!

If you disengaged the fast idle screw, the choke does not engage. I found I can always start my truck toyota 1977 20R engine. If it is a COLD DAY I keep my foot on the gas pedal till the truck warms up a little, even without the temp gage needle moving much. I back down driveway, stop at my mailbox by then she is ready to go. That way when I get to a stop light my idle stays nice easy comfortably my truck runs cool, if a lot of stops or stuck in traffic temp goes 1/4 not to hot. I will see what happens in hotter weather, but; I try to run in early mornings early afternoon now anyway since COVID.

I have a merceuiser 5.0L 305cu GM motor in my boat. With a Rochester QuadraJet carb. Every time it’s cold it’s super hard to start when I am trying to launch it at the boat ramp. Any time I turn it off out on the lake after it’s warm it starts up immediately. I have ethanol free gas in my tank and appropriate ratio SeaFoam additive. I need to else’s more about the carb choke. I have a black and purple wire that’s next to carb and it isn’t attached to anything.

Actually the vacuum break (or choke pulloff is what some call it) is what open the choke plate slightly upon start up. After that the choke unloader spring is responsible for opening the choke plate as it heats up

Thank you very much for such a great explanation!

Adjust your fast idle screw to release some tension on the fast idle CAM, this will allow the choke to close when engine cools.

Thanks for video going to adjust mine today on my 73 transam been having trouble starting on warm startups starts fine cold and hot

Hi Merry Christmas 2019. I have 1981 Chevy C10 305 8cyl w Quadrajet carb. I seen this video about a year ago was trying to get to start. Today I noticed you said about the throttle adjustments and you said if it stalls after starting to adjust the full throttle. That's what my carb does it stal after staring. Truck is old previous owner abused it. He had put a small wire around the secondary arms.

Mine dont want to relax on the idle screw. Shut it off it does. But id say it sticks cuz the car wont relax on idle screw... so witch was would i turn the thing thing. Counter or clock wize.

So what if my carb choke is stuck on and won't go down just stays choked. Runs at 1200 or so it sounds.

Quadrajets are so missundertood and so easy to tune.

nice wish u showed a carter 4bl afb choke setting with hot air adjustment

On a Quadrajet in colder weather is it better to adjust the choke rich clockwise than lean counter clockwise ? I have it on 1 notch rich sbc still cranks with like 7 pumps.

You are a lifesaver thank you

When it's cold, not as cold like where u live but southern California cold weather, my 84 chevy blazer 4x4 is hard to get started. I have to pump it about 7 to 10 times. Then idols high and won't kick down until it's been running for about 20min. My choke light never goes off at all also. Any ideas??

This is great info, i am having a problem with my 88 cutlass Supreme classic that maybe you can help me with, i just put a remanufactured carburetor on and my choke wont come off of fast idle. When it is cold the choke plate is closed just like in this video. But as it warms up it idles up higher and the choke wont disengage unless i flip the choke cam lever by hand and then it idles down where it needs to be and then as soon as i give it gas, rev it or drive it, it goes back on fast idle again. What is the problem? Thank you in advance.

The choke plate on my car us loose it doesn't move at all when started or when giving gas it stays open. The car stalls out. Is there a problem with that is the linkage messed up or somthing because when I touch the choke door it has no resistance it just flops around.

Hey I have a Rochester Dualjet 210 electric choke.. I really have no Idea what my friends did but when engine is warm and off my choke plate is wide open and I press on it the plate and it will not close and is about a good 1/2 inch open it feels like something is blocking it from going down. And whmm enjoy I hit the throttle it will slap shut

Hey man my choke doesn’t open or close it’s just open wide open I’m new too this whole carburetor family so is that a good thing or a bad thing ??? I need help because now my car won’t go past 30mph do you think that has to do with the carburetor ? And I don’t have a heat riser tube do I need it ??

I hold choke open with wired. An my foot is choke to keep it running. Until it warms up.

Thanks bro!

I noticed that u have 2 Belts and engine looks like there ant much on top of it u can actually c the top of engine.. did u cancel all the emissions junk n hoses ? If u did can u make a video on it . I have a Pontiac with a stock Chevy factory 305 all there n want to cancel emissions c if can breath better n give extra power..

Quick question my battery light and choke light is on and when I accelerate it goes off I have a 87 caprice Ls

I got black exhaust out my 87 caprice dirty carb maybe it came outta no where

After I adjusted the choke I had to crank down on the Fast Idle Screw so the engine didn't die. Hopefully on the next cold start the fast idle cam will be in its correct position. If not I am guessing that I will need to play with that screw or search for a Fast idle Cam adjustment.?

I loved the quadrajet carbs on a 350 engine with the 350 turbohydramatic transmission

Your fuken beast bro 💪🏽