Snapped an idle mixture screw Carter AVS - HELP!!

[1968rt]

I have an AVS that the mixture screw was frozen and I snapped it. Drilled a pilot hole, tried heat and an extractor, no luck. The housing is OK not screwed up yet. What would you say to sending a mig wire in the hole and create a new head??

 

[PurpleBeeper]

Dang, I’ve been running Holleys for a long time…. Does that mixture screw have a “pointed nose” and stick into a precision hole or something??? I’m guessing it’s a precision screw/hole. If yes, I don’t think your idea would work. Maybe try a top quality EZ out and go nuts with the torch? What have you got to lose?

 

[nitro_rat]

Your hole looks pretty centered, I think I would continue stepping up drill size...

 

[pnora]

At this point I would drill it to the size needed to retap the hole. Drill it a little at a time until the tapered tip is loose and get it out of the hole. Thread the hole and get a replacement screw.

 

[QuickBpBp]

If it's a numbers carb for your car talk to Scott Smith at Harm's auto... I am sure he can help.

 

[1968rt]

At this point I would drill it to the size needed to retap the hole. Drill it a little at a time until the tapered tip is loose and get it out of the hole. Thread the hole and get a replacement screw.

I had a similar problem with a Holley and I did exactly that, but the Holleys needles were brass. These are steel WTF

 

[nitro_rat]

Patience...

 

[LowBikeMike]

Try a left hand bit when drilling it out. Might get lucky and unscrew it.

 

[turbine68rt]

If you have a 68 R/T an original carb would be a 4429 for an automatic. 4428 for 4 spd. All of the AVS's I've seen had the short brass screws behind the plugs. What number carb do you have?

 

[Some Car Guy]

The left hand bit idea is good. I’d try more and different penetrating oil. You’ll laugh, but Prolong is nasty stuff to put in your engine. However, it’s a great caustic penetrating oil. Try Amazon for a spray can. Can you spray the backside?

 

[Geoff 2]

I think it would be near impossible for the home mechanic to remove that screw. If you intend to drill it out,you would need to make a fixture to keep the drill on centre & not wander off. It would be easier to get another carb.

 

[OneWheelPeel]

I think it would be near impossible for the home mechanic to remove that screw. If you intend to drill it out,you would need to make a fixture to keep the drill on centre & not wander off. It would be easier to get another carb.

I say go for it even if it’s near impossible, you could get it right, I doubt the drill bits are a fortune so why not try?

 

[Bee1971]

4968 S

1971 440 HP Auto

 

[KozmicKuda]

You could try creating a small divot or ledge with a Dremel cutter in the face of the screw. I have a 1/8" diameter carbide ball that I'm thinking might work. Do it at the 9 or 10:00 position. Clamp the body of the carb to a bench. Heat the body around the screw with a small butane torch. Using a very small punch or a tool you make, engage the notch with the tool and carefully drive the screw down toward the bench concentrating on the left hand side of the screw. The goal would be to break it loose and it should unscrew after that.

Another idea would be to drill through the screw with a small diameter bit, maybe 1/16". Of course you don't want to go too deep. Then add a rust penetrant and let it soak. Or if you can figure out where that passage goes into the carb, you might be able to load it with penetrant from the backside.

 

[PurpleBeeper]

One last idea I had…..just start to tap the hole now & let the remainder of the screw get chewed up by the tap (?)

 

[pnora]

One last idea I had…..just start to tap the hole now & let the remainder of the screw get chewed up by the tap (?)

Not a good idea. That tap will run the needle tip into the seat and there is a good chance it will damage the seat.

 

[1968rt]

Im going to try what pnora suggested. Drill down just past the threads, then push out the needle from the butterfly side and then try a tap. I dont need the carb, but in working condition it should be useful to someone.

 

[bobsgtx]

Some later model carbs. had set screws to limit the mixture screw adjustment. I would remove the plug above the screw and see if there is a set screw or something to limit the removal of the mixture screw. I had to do this on a later model AFB.

 

[Orig69]

Im going to try what pnora suggested. Drill down just past the threads, then push out the needle from the butterfly side and then try a tap. I dont need the carb, but in working condition it should be useful to someone.

View attachment 1805564

As long as you don't drill all the way through it, the carburetor will still work.

 

[pnora]

As long as you don't drill all the way through it, the carburetor will still work.

Sure it will but how do you adjust it???