How to adjust your QuadraJet's Fast Idle

In this video I demonstrate how to adjust the fast idle on the choke of this Rochester QuadraJet. The same procedure should work on most QuadraJets no matter the GM division it was used on.

[@nickstewart3725]

I seen Rocket 350 and had to subscribe!...my name is Nick and I'm from Michigan and I own a 1978 Delta 88 with a 350 Rocket as well...its a super easy project car I picked up after my wife passed away January 7th of this year...I was a Technician at a Oldsmobile from the mid 90s up until General Motors decided to drop Olds for good then we switched to a Buick dealership...I still work at a ASE master automotive technician at a independent shop now and restoring cars and building engines is my hobby...so I'm glad to find another Oldsmobile enthusiast like me and I look forward to your videos!

[@f119045]

Hi Nick, Nice to hear from another Oldsmobile enthusiast. Sorry to hear about your wife, but happy that you have found a project car to keep you busy. Best of luck with your Olds and I will keep making videos….Dan

[@nickstewart3725]

@@f119045 I really appreciate your condolences!...I absolutely love the car but some parts are hard to find like wheel well trim...emblems...etc...but doesn't stop me from the hunt!...I'll stay tuned for more videos!

[@20alphabet]

*saw

[@glennmanchester5696]

I lost my wife a yr ago and im definitely an olds pontiac fan from way back always dusted the small block chevy guys who had big money engines with my boneyard engines they hated me lol sorry I only spent 200 on my engine and you spent 2000 and still lost the race dummass

[@TheOutlawGeneralBacon]

Just got an 82 Rivera 307 with 35k original!!! Needs some love.. but beautiful.. anyway.. I have a fast idle.... Hopefully after this video, I won't.. 🤷🏻‍♂️

[@theusconstitution1776]

Very good explanation for something that is very difficult in real life to see touch and adjust and filming it must make it two or three times more difficult at best thank you very much for all your effort and I will now go out in the garage and see if I can make mine work❤️‍🔥🇺🇸

[@f119045]

Glad you enjoyed it!

[@justinwatch]

I put one of those carburetors on my brother's Mustang with a Mr. Gasket spread bore adapter and Ford sent me a cease-and-desist letter.

[@glennmanchester5696]

Lol

[@slewfoot6608]

😂😂😂

[@fishonnelson2353]

Great job and thank you for the education!

[@f119045]

Thanks for watching!

[@kennethrollerson4898]

Thank you very much ! Very helpful

[@f119045]

Glad it helped!

[@greatdane145]

Are you sure that you are supposed to block that vent on the choke Vakuum?😅

[@slewfoot6608]

thanks for the info!

[@TheyreStillOutThere]

That fast idle cam makes my throttle stick open on my 73 Vista Cruiser. I have to blip the throttle to get that choke linkage to release and then my throttle unsticks. Any tips on adjustment?

[@f119045]

I would say from the description I don’t see a problem. Blipping the throttle to knock the choke linkage off high idle sounds pretty normal. If that’s all that is wrong your carb its working pretty good.

[@TheyreStillOutThere]

@@f119045 I should’ve been more clear-I can’t give it a couple squirts before trying to start the car without the throttle sticking wide open and the choke blade sticking open too. It doesn’t want to start with no preliminary fuel squirts, but squirting fuel means I stick my throttle open and the choke blade opens, so it just won’t start. It’s not a throttle cable issue, it’s purely just a linkage problem. It’s a bone stock 100% original Quadrajet. The throttle even sticks open while driving sometimes, which is terrifying.

[@f119045]

Sounds like the return spring(s) are not doing their job. The throttle not returning or sticking needs to be addressed ASAP. I have not seen that issue before but for sure the return spring needs to be examined and or sticking throttle plate needs to be freed up by examining its operation more closely. Once that’s fixed you can return back to the choke issue.

[@TheyreStillOutThere]

@@f119045 Throttle operates completely normally and does not stick when engine is completely warmed up to full operating temp, which takes a solid 20-30 minutes of idling. Anything before completely warmed up to full operating temp, the choke linkage locks the throttle open, even if it's more than sufficiently warmed up. It's a bizarre issue and I have found nothing online remotely similar to this to try and diagnose. Pulling my hair out. Don't want to keep bugging you, just thought I'd reach out to see if you had any ideas. Cheers.

[@f119045]

@@TheyreStillOutThere Well this is making more sense to me now. If you have the hot air choke like the one shown. That black plastic round dial control how hot the engine gets before releasing the choke i.e. the throttle. To control that loosen up the three screws that hold the tension. That dial should want to turn clockwise releasing the bi-metallic spring pressure. That spring pressure is keeping the choke running high and not releasing the throttle until the spring is very hot. By unwinding the spring you are releasing the throttle earlier and letting the idle down quicker. Let me know if that helps you out.

[@Oak690]

Does this procedure also apply to an electronic quadrajet?

[@f119045]

I never worked on an electronic carb but if it has the same adjusters available as mine it should.

[@rwb7651]

I have a ‘68 Cutlass S with an after market carburetor and filter. What would the original look like? I can’t seem to find one.

[@f119045]

My original would have been a 2 Barrel Rochester carburetor.

[@itspurgatory]

So are you turning it to the right?

[@f119045]

Yes like I am tightening the screw.

[@rickaitchison3695]

Bad Idle, My Problem wasn't with my 1978 1/2 ton Chevy Cheyenne that ive owned since DEC of 1979, My 4B Rochester PN/17057202. had a bad Idle, I rebuilt it, same Problem, took it to a machine shop, they deck it, i had minor leak from the base to the Main, still bad Idle, the Problem wasn't in the Adjustment or the Carburetor, after 3 weeks of Trouble shooting and watching my truck rock like a boat at Idle. This Problem was caused by the Original Automatic Transmission Vacuum Modulator. The Original Automatic Transmission Vacuum Modulator Rubber Diaphragm of 43 years of driving finally wore out, the intake manifold acts as a vacuum cleaner and was sucking up Automatic Transmission fluid through the metal hose and dispersing it to my 8 cylinders causing fouled Plugs "Bright Read" and dirtied my oil, For $38 Bucks a New Modulator New AC R45TS Spark Plugs, New Oil Filter, 10/40 Oil Pennzoil, My Problem Solved.

[@ronclifford3336]

I bought a rebuilt hot air choke quadrajet off ebay for my 78 Chevy c30 wrecker with a 350. Turned out mine was a what you are calling divorced choke setup (had the coil in the manifold) so I put the one I bought off of ebay in the closet and went and got another one that had that type of setup. They called it a Manual Choke system. The sales add for the hot air choke carb said it would work on my wrecker but it didnt? At least the choke part didnt? Everything else worked on it. Same bolt pattern, accelerator linkage and all, just didnt have a way to hook the hot air choke up? That could be a 350 manifold? I know the engine in my wrecker is a 350 and it has that type of choke (Manual/Divorced)? I love the older cars, course I grew up with them, but I have several. They are a lot easier to work on. My first car was a 54 Ford Customline.

[@f119045]

Manual chokes are operated like the name states manually usually by a pull-out lever. When the engine is warm you must shut the choke off yourself. A divorced choke just means that coil that runs the choke is separate from the carburetor. Usually sitting on the manifold connected to the carburetor by a metal rod. My choke coil is on the carb but for that system to work it needs manifold heat information from a vacuum operated tube that is inserted inside a space in the intake manifold. I do not have a space for the full tube. So, I modified mine to use a part of the tube it still pulls heat/air from proximity to the manifold. Its not as accurate but it gets the job done. BTW I like 54 Ford Customline’s too😊

[@grand73am]

If you haven't resolved it yet, I suggest buying an electric choke coil from a q-jet parts supplier like cliffshiighperformance, my go-to q-jet guy. It's not hard to convert the hot air choke to electric choke. And then all you need is to connect the electric choke wire to an underhood wire that is only hot when the key is on. There's normally a wire like that connected to the wiper motor, so use a test light to find that wire on the wiper motor, and splice into that wire for the power to the electric choke. Works great and dependable. Much more convenient than trying to make old hot air tubes fit and work. Plus it sounds like your intake is not for a q-jet with the hot air choke on the carb, but instead is for the divorced choke, so it doesn't even have a provision for hot air tubes for the hot air choke mounted on the carb. 78's normally have an intake that is for the hot air choke on the carb, since they started using those in 73. But since you have a truck, maybe it's an exception. Or maybe the engine (or at least the intake) was replaced at some point with an earlier year engine/intake that used the divorced choke setup. But regardless, installing the electric choke into the hot air choke housing cures that mismatch of parts.

[@Avenged188]

At 1:36 there's a hose with a screw in it.. what's that supposed to go to?

[@f119045]

This carb was from a later car I think a 74 Cutlass with most likely more options. That is a full vacuum port that I have no need for on my car so I took a vacuum line and screw and plugged it. Otherwise it would leak vacuum and make the car run poorly.

[@Avenged188]

@@f119045 TY!!! my 76 has the same thing, hose with a bolt I didn't know what it was haha

[@grand73am]

@@Avenged188 Yes, it's just a way to cap off an unneeded port without buying caps. You can buy a pack of assorted vacuum port caps from an auto parts store. I prefer the colored vinul ones. The vinyl caps last much longer than black rubber ones.

[@RoninAvenger]

@@grand73am yeah I’ve replaced the rubber ones twice in 2 years on my Rocket 350’s quadrajet

[@20alphabet]

Things like can be expected when you have the wrong carburetor on the manifold.

[@f119045]

I know what you mean.

[@Schlipperschlopper]

Sadly soon all gas cars will be banned in EU and most states of USA and CANADA!

[@info-iho2870]

Until then, enjoy your car. They can ban anything they want, but they can't really do anything about, it is just talk.

[@brianwilson415]

That totally sucks!!

[@Schlipperschlopper]

sadly the want us to only use e bikes and scooters @@brianwilson415

[@georgesabol459]

Why didn't you just replace it with an electric choke? It drops right in to that housing. All you need is a GM 12 volt version of that heat from manifold unit. 1 wire from the ignition start & run, a full 12 volts of course.

[@f119045]

That is a good idea, I guess that never crossed my mind.