Replacing Quadrajet Needle & Seat

[@brianwilson415]

Your attention to detail is impressive! Nice work.

[@76vette]

Thank you for watching! 😊👍🏻

[@me9303]

Very nice carburetor/ dinner plate clean.

[@Rattdogg4q2]

I noticed the baffle on your accelerator pump well is missing ....nice video

[@76vette]

Thank you for watching! 😊👍🏻

[@satamanschmidt3428]

I see below that you said you sealed the well plugs with epoxy but that's not a sure bet. They way to tell if they are still leaking is detailed in Cliff's book and involves blowing compressed air into the jets and seeing if air bubbles form on the well plugs when soaked with soapy water. The epoxy fix doesn't always work. You might want to have to remove the plugs (best tool for this job is an old school dent pulling slide hammer with a screw on the end of it) and drill and tap the holes and epoxy set screws into them. That almost always gets the job done.

[@76vette]

So far the epoxy seems to be doing the trick, but you’re correct about the set-screw fix being more permanent. 😊👍🏻

[@franciscotrujillo4961]

hello, at minute 15:10, remove the needle seat, I have a problem with my rochester quadrajet carburetor and it is that I think the needle is hooked to the holes on the sides of the needle seat and that is why it is sticking It floods a little, do you think that is the cause? both needle and seat, float, everything is new. Do you think that the position of the needle that you show at minute 16:32 is better and would at least remove my doubt that that was what happens? greetings and thanks for the video

[@76vette]

Hi Francisco, As you probably know, diagnosing something like this from a distance is impossible. I am not clear as to why you think the needle is “hooked” to the seat unless one of the components was damaged and probably something that you would be able to see and feel just by testing its movement. As far as the windowless seat, I think that design is far better to help keep fuel in the bowl. But that’s it. My advice is to have someone familiar with Quadrajets inspect the carburetor to ensure all the components are installed and operating correctly. And I would also double check the level of the float. That could be the cause of the flooding. Good luck snd thanks for watching. 😊👍🏻

[@franciscotrujillo4961]

@@76vette thank you very much greetings

[@76vette]

@@franciscotrujillo4961 You’re welcome! 😊👍🏻

[@alexjandroarias7768]

K tal.. saludos desde México!... la forma segura de sujertar la aguja de gasolina principal es : colocarla entre los orificios del flotador... porque asi como la colocas se puede ser la causante de ahogamiento .... y consumo de combustible...

[@76vette]

Thanks for watching! Gracias 🙂👍

[@jacerichard8067]

What is the brass plug in front of needle an seat ? With the two flats on it to unscrew it ? I took mine off while cleaning carb an do not know if it needs to bottom out or back off so many turns ? It has a spring in it

[@76vette]

I think you are talking about the APT screw (Adjustable Part Throttle). Before removing it, you have to count the number of turns in (until fully seated) since they are calibrated at the factory. If you did not, Quadrajet Power has an excellent video on how to adjust the APT correctly. They also sell the right tool and every other Qjet part you may need. kzbin.info/www/bejne/jKLbiXmtoLloa8k

[@jacerichard8067]

Thanks greatly appreciated

[@rustyvanthoff9549]

Did this fix work on the drain back?

[@76vette]

My carb no longer has a drain-back issue. 😊👍🏻

[@donames6941]

If the bowl is dry after a day are more its the cups under the needle jets leaking and some times they get so bad it floods the motor in as little as 5 minutes of non running replace them or JB weld them

[@franciscotrujillo4961]

One more question friend, I'll tell you, I have a Rochester Quadrajet carburetor and I want to change the primary nozzles along with the primary needles, and since there are different numbers of nozzles and primary needles, I have to deduce that depending on the number of nozzles, I must set the needle number equal to the nozzle number? I mean, if I put number 0.72 primary nozzles, should I put number 0.72 primary needles? I understand that in this way, the idling engine has the primary nozzles blocked with the primary needles, since they are of the same diameter, and that when accelerating and losing vacuum, the primary needles begin to rise, allowing fuel to pass to the primary jets, is that correct? all the best

[@76vette]

Hello Francisco, Your question is a bit confusing. I think by primary nozzles you are referring to jets. The Quadrajet fuel nozzles are inside the venturis and, as far as I know, they cannnot be changed. I guess they could be drilled, but I don’t think that would be a good idea. Also, if by needle sizes you mean metering rods (sometimes they are referred to as needles), I always use whatever size/taper is standard. Quadrajets are calibrated by engineers for specific applications and that’s why I keep mods to a minimum to avoid affecting performance. Something as basic as using a different air cleaner, for example, will affect carburetor calibration and performance. The idling circuit is quite complex. At least to me. And the transition from idle to primary circuit is well above my limited level of understanding, especially since it involves maintaining the ideal air to fuel ratio which is why I rebuild Quadrajets to factory standards. Having said that, your description of the basics of idling to primary circuit operation sound good to me. All the fuel delivered to the primary main nozzles flows past the jets controlled by the metering rods connected to the power piston. BTW, the primary metering rod size does not mean you should get equivalent jet sizes. I believe the number and letter indicate taper diameter. I really wish I could answer your questions with more detail. Unfortunately, I can’t so I hope this makes some sense.

[@rebeccadykshorn9700]

Where did you get the rebuild kit?

[@76vette]

Either quadrajetpower.com or quadrajetparts.com Both are responsive, have parts in stock, ship fast, and know Quadrajet carburetors. 😊👍🏻

[@franciscotrujillo4961]

Q fallo daba el motor ? Inestabilidad , sonido grave , mala aceleración, ....

[@76vette]

Nothing wrong with the engine. It was time to rebuild the carb.