Leaking Quadrajet

[67RS/SSx2]

The quadrajet on my 402 is weeping around what I think is a pressed in plug. It is right where the screwdriver is pointing. Doesn't leak a lot but will begin a slow drip after a few minutes of running. This is keeping me from driving the truck.

What is the best way to fix this? I was thinking maybe put a hole in the center of the plug then work it out of the carb. Not sure where I would get a replacement. I doubt O'Reillys or AutoZone carry them. Any words of wisdom?

[HotWheelsFan]

Yes, it is a plug that is pressed in. If you remove it, you can epoxy it back in, get a repair kit, or new plug.

Been awhile since seeing one leak, so I can't remember doing any particular repairs other than using epoxy.


Bob

[Steeveedee]

^ Yup. I've never seen one leaking, and I've worked on vehicles for many years. Lucky you! BTW, in the area just forward of the primaries (and the choke plate) you appear to be missing the idle vapor vent valve.

[67RS/SSx2]

I am afraid the plug will be ruined by removing it. Where can I get a repair kit or replacement plug?

Thanks!

[geezer#99]

I’d jb weld it.
Had one on a Holley did that.

[Getter-Done]

This stuff works for years.


(Seal-all is the adhesive mechanics and hobbyists trust for all their automotive and garage repairs. It Adheres with superior strength to most substrates and resists gasoline, oil, paint thinner, and solvents. Seal-all does not require mixing or heating and will not become brittle.)

Link:https://www.autozone.com/sealants-gl...628dc95255514b





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[mr.mud1]

I have seen them leak as well as several other plugs in the carb body.i doubt you'll ever be able to buy a new plug and if could,you won't be able to install it like factory.i epoxy them all or JB weld when I do an overhaul whether they have been leaking or not.you might have to remove the carb to make it easier to work on but as mentioned some 5 minute epoxy or JB Weld is your best bet.

[67RS/SSx2]

Originally Posted by Steeveedee

^ Yup. I've never seen one leaking, and I've worked on vehicles for many years. Lucky you! BTW, in the area just forward of the primaries (and the choke plate) you appear to be missing the idle vapor vent valve.

Have to do a little research. I do not know what that is.

[mr.mud1]

What number is your carb?it's vertical on the driver's side of the carb.if your truck is a 72 and an automatic, it should be 7042208 and there is no vent on the front of the air horn.early quadrajets had a piece of linkage hooked to a round rubber plug that lifted up to expose a vent hole.if you have round vent opening in the air horn,you have the wrong carb or the wrong air horn (top) on your carb.

[68Gold/white]

JB weld will not hold. There is a product called JB weld marine, will hold. You may to have a parts store order it. I get mine from Napa.
Don’t try to take the plug out.

[racerface]

Go to cliffshighperformance.com you can e-mail him, buy kits from him or send your carb to him. I am lucky enough to live a hour or so north of him and took a carb to him. Wound up spending 3 hours there and he showed me a lot about Quadra Jets and how today's fuel tears them apart. he's the only carb guy that I have seen make a Quadra jet run like fuel injection and that was before I knew who he was.

[Steeveedee]

Originally Posted by mr.mud1

What number is your carb?it's vertical on the driver's side of the carb.if your truck is a 72 and an automatic, it should be 7042208 and there is no vent on the front of the air horn.early quadrajets had a piece of linkage hooked to a round rubber plug that lifted up to expose a vent hole.if you have round vent opening in the air horn,you have the wrong carb or the wrong air horn (top) on your carb.

True about not having the idle vapor vent, except I think that that only applied to SBCs, because they got the EEC from the fuel tank to the vapor canister, and BBCs didn't. He could still have a mutt carburetor, but the idle vapor vent isn't necessarily wrong. I went out and looked at the (original, '70) carburetor on my truck, and based on the angle of the picture, his carburetor may not have the idle vapor vent. You can see the holes on the left, and they look the same on my carburetor, but I don't have that vent. We'll need to see more of it before we can determine what it really is, but it could well be correct.

[MySons68C20]

Originally Posted by 68Gold/white

JB weld will not hold. There is a product called JB weld marine, will hold. You may to have a parts store order it. I get mine from Napa.
Don’t try to take the plug out.

What do you do with the marine stuff to keep it from leaking?
I'm not doubting you just want to learn the method.

[geezer#99]

Appears plugs are available. Not sure what size you need. A link just in case they’re needed.



https://quadrajetparts.com/expansion...y5-p-2734.html

[68Gold/white]

The Marine JB weld is just a different formulation of JB weld. A 2 part epoxy, just like regular JB, mix it 50/50 and apply it to the clean/ dry surface, let it setup or, 24 hours.

[BigBird05]

You should take the carb off and check the bottom side of the float bowl. The area between the the throttle plate and the bowl. There are two more plugs there that are known to leak. That leak is very common. GM even had a bulletin about it. If your carb has not had a rebuild done to it, you probably need it done anyway. Todays gas is very hard on the old style gaskets, seals and the accelerator pump.

[vics stuff]

Originally Posted by BigBird05

You should take the carb off and check the bottom side of the float bowl. The area between the the throttle plate and the bowl. There are two more plugs there that are known to leak. That leak is very common. GM even had a bulletin about it. If your carb has not had a rebuild done to it, you probably need it done anyway. Todays gas is very hard on the old style gaskets, seals and the accelerator pump.

I have to agree with you 100%
Vic

[HO455]

Those plugs are usually steel disks that were set into specially machined holes in the casting. Then the casting was punched with an arbor to crimp the pot metal around it, sealing the hole. Unfortunately the disks and the pot metal casting have slightly different expansion rates when heated. Over time the disks will distort the pot metal and leaks occur. If the engine/carburetor was badly overheated at some point the distortion will be greater.
When repairing the obstacles to a permanent repair are large.
First there is no gasoline proof epoxy, only gasoline resistant epoxy.
The epoxy, the disk, and the pot metal will have differences in their rate of expansion and contraction.
The area the you apply the epoxy to must be absolutely clean and like paint it has to have the proper surface preparation for the epoxy to grab the disk and the casting.
The above problems mean that a permanent repair is not likely to happen but getting 20 or 30 thousand miles is not out of the question
If you decide to remove the disk careful grinding of the crimped area is the way to go. Think Dremel. Not a die grinder, or a bench grinder, or drilling it out. You don't want to crack the pot metal. Too much shock or localized heat can cause micro-cracks which are next to impossible to seal.

[BROWN 70]

hi, I have a 7041211 that leaked at that spot. I used marine tex. resists gas big time. cliff ruggles might have a plug. or, take the plug out and thread the casting for a allen plug with marine tex on the threads. good luck, BROWN 70

[67RS/SSx2]

Picked up some "Seal All" from Autozone. Cleaned the plug and surrounding area with steel wool, then scotchbrite pad, then rag and blew off. Used the seal all (two coats) and I think I am good to go.

When cleaning the plug I noticed material that was dark gray or black coming off the plug. I am thinking something (JB Weld or similar) put on there before to seal it and it eventually became brittle and flaked off, causing the recent leak.

Below is a pic of my carb and a pic of the carb number. I am not sure you can see the number from the photo but it appears to be 7042218. My eyes aren't what they used to be.

Thanks to everyone! I think I am good to go for the time being. Later I may pull the carb for a rebuild.

[BigBird05]

When I was young ( in the 50's ) my father used a product called Gasahall. It was red and worked real well. Turned your fingers red for a week. I don't know if its made anymore or if you could even find any.

[mr.mud1]

Originally Posted by mr.mud1

What number is your carb?it's vertical on the driver's side of the carb.if your truck is a 72 and an automatic, it should be 7042208 and there is no vent on the front of the air horn.early quadrajets had a piece of linkage hooked to a round rubber plug that lifted up to expose a vent hole.if you have round vent opening in the air horn,you have the wrong carb or the wrong air horn (top) on your carb.

hi,glad to hear you're making progress.i was mistaken when i said your carb should be 7042208,i had my finger on the incorrect key.a 7042208 is a 350 carb,402 should be a 7042218 and that's what you have,although a 7042206 shows up as a 402 carb as well.i could see by your latest picture,there is no vent in the air horn,and that's the way it should be.

[68Gold/white]

When you get ready to build the carb, give Cliff a call (1-740-397-2921). He will be the one answering the phone.
He quit building carbs, a year ago, or so. He’s just selling parts now. You get more parts inside one of his kits, than any parts store kit! He has 3 different types of kits.
Don’t scrimp and buy an eBay kit! Cliff can set you off up with new jets, metering rods and all parts you SHOULD really replace or a build, specifically for your engine. Today’s gas is so very different, even from gas 20 years ago. He knows how to compensate your carbs calibration, for today’s gas!
The biggest plus, when you buy his stuff, you get awesome tech support!!!
www. Cliffs high performance.com

[Steeveedee]

I bought Cliff's book and a kit from him a few years back. I got the cam for the secondary metering rods in the kit. Mine had broken, and fortunately it's nylon and made it through the engine without causing damage. That's the only one I've ever seen broken, and I've rebuilt dozens of carburetors. I took the baseplate to a local-ish shop for the bushing installation. The guy wasn't too happy that he didn't get the whole rebuild. But I try not to spend money when I don't have to. Cliff was as surprised as I was that it was the original carburetor.