Tuesday, February 25, 2020

Resealing Quadrajet Well Plugs | Part 2

Carburetor wells were sealed by the manufacturer with aluminum, brass, or lead plugs depending on the date of manufacture. Plugs were intended to keep gasoline inside the carb.

Once the plugs fail, fuel leaks down into the intake manifold and—at least in my case—makes hot-starts an unpleasant and difficult task.

The engine turns and turns until it finally sputters to life, only to run horribly for 30 seconds or longer.

Not cool.

As I chronicled in Part 1, you must take your Quadrajet apart to properly seal all the well plugs. I mean, if you're going to disassemble the carburetor you might as well reseal everything.

I read somewhere that Rochester found an effective fix for the leaking well plugs issue and implemented it in 1975.

However, my '76 Corvette rolled off the assembly line in October of 1975 and the original Quadrajet plugs leaked, so I am not sure if the fix I read about was implemented at a later date or if it's fiction.

Anyway, the photo below shows the primary well plugs after I scraped some of the old Epoxy that was used to seal them when the carburetor was rebuilt a couple of years ago.

After a while, the Epoxy failed and they started leaking.


The problem is that carburetors get pretty warm while the car is running, and regular epoxies will only seal the leaking well plugs only for a while. A combination of heat, vibration, and ethanol-blend fuels ensure an eventual failure.

A better alternative to regular epoxy is marine epoxy, which is not only waterproof but also chemical and petroleum (fuel) resistant.

My original plan was to use MarineWeld. However, while visiting my local O'Reilly Auto Parts store, I came across a J-B Weld product that looked even better for the job: J-B Weld Dark Grey TankWeld Gas Tank Repair.

The product is a putty that you knead and then spread over the area you want to seal.

Working time is five minutes which is plenty for small jobs like these, and TankWeld fully cures in one hour.

I started by sealing the primary well plugs so I sliced a small piece of TankWeld off the roll and removed the outer protective plastic. I then kneaded the material with my fingers ensuring it was fully mixed. At this point, it is ready to be applied to the target area.


As the photos below show, TankWeld adheres nicely to the carburetor well walls and it can be spread smoothly and evenly over the area. And since it is a putty, you can spread it as needed and provide thick coverage in key areas.


However, it is worth noting that carburetors are built to tight-tolerances, so it's not hard to add too much TankWeld. Ask me how I know.

The fix is easy though as once the stuff hardens it can be filed just like you would a piece of aluminum, for example. The stuff hardens like a rock!


So I carefully and lightly filed a couple of areas where the TankWeld was interfering with the base plate. This took care of the excess and the gasket and base plate fit perfectly.


Once all the well plugs were sealed, I started reassembling the Quadrajet, but to make my life easier, I compiled a Reassembly Sequence list that covers each and every step I followed to reassemble my carburetor.

The first part I installed was the security lockout lever., followed by the choke assembly.


Reinstalling the choke can be a little challenging since it also must be connected to a small keyed lever that fits in the well behind the electric choke assembly (red arrow below).


The photo below shows the lever and actuating rod in place to illustrate how they fit inside the well.


And this is the small lever that the choke shaft connects to so the choke flap can operate properly.


As you can see in the picture below, the red arrow points to the shaft that is keyed to the lever, so the choke assembly and the lever must be aligned correctly for the parts to be connected properly.


The tricky part is finding a way to position the lever inside the well at just the right angle (as shown below), so when you push the choke assembly in, the shaft and the lever will be lined up so they engage properly.

Probably the easiest way to get the lever hooked up is by using a thin magnet as shown in one of the videos listed in Part 1. Unfortunately, the magnet I have is just too thick and it doesn't reach far enough into the well, so I had to improvise...


...and this is what I came up with. Not the prettiest solution, but it worked, and that's what counts.


I was able to reach into the well while positioning the lever in such a way that I could insert the choke assembly so it would sit correctly. You have to take your time and use as much patience as you can muster in order to get this part installed.

As you hold the lever in place and its keyed portion aligned with the hole (red arrow below), you have to somewhat align the choke shaft while gently pushing the whole assembly into place. Once everything is aligned properly, it just drops in place.

The back of the assembly has a hole that secures the secondary lockout lever (blue arrow below) between the carb body and the choke assembly body. And as I mentioned earlier, the lockout lever has to be in place before you reinstall the choke assembly.


Once all the components are in, you can reinstall the screw that secures the choke assembly body in place (red arrow). At this point, a tug of the needlenose pliers will release the lever.


The photo below shows the choke assembly shaft engaged with the lever (red arrow).


In order to connect the actuating rod to the lever, you can gently push it to the side with a flathead screwdriver while you connect the rod (photo below).

One important thing to remember is that even though these systems can be a little tricky to hook up,  you must NOT bend any of the rods to make them fit. Once they're out of whack, the systems they operate will no longer work properly.


And this is how the actuating rod and the choke flap lever should look when installed correctly.


Next, the check ball and screw are reinstalled, followed by the primary jets.


In Part 3 of this series, I will have a video showing the complete reassembly of my Quadrajet carburetor.

In the meantime, feel free to download the PDF file of my reassembly sequence if you find it helpful.

Thank you for following my '76 Vette Blog!



Product Links... (#sponsored)

J-B Weld MarineWeld Marine Epoxy - 2 oz.
J-B Weld Dark Grey TankWeld Gas Tank Repair
Gumout Carb and Choke Cleaner | Spray 16 oz.
Rochester Carburetors by Doug Roe
How to Rebuild & Modify Rochester Quadrajet Carburetors by Cliff Ruggles

ACDelco Carburetor Repair Kit: Ball, Clips, Gaskets, Screws, and Seals




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