FIXED - AFB 4bbl broken adjustment screw

[Dana67Dart]

Ok all,

Anyone ever recover from this situation. I've broken my share of bolts and screws but this time not my doing, I received the carb this way.
I have not cleaned the carb properly yet so not sure just how much of the screw is still in the hole.

It is a California carb so the adjusters were mechanically limited to rotation. My guess is that someone tried really hard to remove the adjuster (note the set screw is out)

I don't want to create more harm trying to remove the adjuster with my typical removal techniques

Cleaned so much wasp gunk out of the passages, but it is mostly there and in rebuildable shape.

 

[Dana67Dart]

Got brave and removed the other adjuster
Looks like I have the threaded lower section still in the bore.

I'm thinking about creating a threaded dowel and screw it into the upper threads. Use the hole in the center of the dowel as a guide to drill out the smaller portion of the adjuster till I get to the larger portion, then use an easy out or the like to remove it.

 

[Tooljunkie]

If it was a had to save it kind of thing, and not destroy threads i think your aporoach would work.
I could suggest the alum and water thing, but as of this moment i consider it a failure.
The smaller threaded parts are harder to save.

 

[Dana67Dart]

alum and water thing,

Is that a water jet cutter type of operation?
I was thinking of using a relativly large welding rod and kind of spot welding the rod to the top on the adjuster. I nixed that thinking i would probably weld the threads to the aluminum

 

[Tooljunkie]

I tried it on a very small broken tap. Heated it for 40 hours. Didnt work. Tap was probably very hard.

 

[Tooljunkie]

Welding rod idea,would take some testing.
Set amperage low and snap welder on/off. Might work. Or might be a disaster.

 

[Oldmanmopar]

Put the carb in a sonic cleaner at High temp for 40 mins. If the tab is still on it you will be able to turn it out with a needle nose pliers. Sonic cleaner waves will take out any corrosion on the treads to the bottom. The high temp will expand the aluminum body and the screw will get fairly loose. Been there several times with old carbs that some try to rebuild. You guys won't believe how well this works.

 

[65dartcharger]

I have a AFB carb with the same problem! What carbs had those limited adjusting screws?

 

[Dana67Dart]

What carbs had those limited adjusting screws

I know the CAP ( Cleaner Air Package ie Psyco California) carbs had them. there is a little set screw to the side of each adjuster ( may be covered with a lead plug - not sure about that)

I'm going to try the Alum method (thanks Tooljunkie, who will be held harmless if the worst happens) and see what happens. I'm not into this very much so if the worst happens I'm not out much. Wouldn't mind having an ultrasonic cleaner and trying that but car cash is tight right now.

 

[Dana67Dart]

Well I got brave or stupid and decided to try drilling out the adjuster.

Started out with a 1/16" down the center of the shaft, VERY VERY SLOW, so far so good, got down about 1/8" or so. Stepped it up to 3/32" and enlarged and lengthened the hole.

The dang adjuster started to rotate into the bore until it got past the threads. Now it is sitting slightly sideways and the tapered pin part can be seen from the bottom in the venturi.

I looked into the other bore and saw that the large plugged hole next to the adjuster makes a cavity large enough to remove the remains of the adjuster. So I drilled out the lead plug and luckily it can out in one piece except for the hole in the center I drilled. I thought about trying to pry it out but figured I would do more damage to things.

So after some additional drilling to make the remaining threaded part of the adjuster smaller it came out.

I thought the threads in the adjuster hole were stripped out but it turns out that they were just dirty. I will run a tap through and see how the existing adjuster fits. It does not look like there is any other damage so now I can start to rebuild it.

Some things I might have done differently:
1. I would use left hand drills (in my case it would not have come out as someone had screwed the set screw hard into the adjuster threads and messed them up good. If it had come out I would have had to helicoil for sure)
2. A drill press (to keep things parallel, centered and aligned)
3. drill the smallest hole as deep as possible (when i went to the next larger size bit, turns out my pilot hole was a tad off center and it caused the larger bit to walk out the side)
4. drill dead center on the adjuster (see above)
5. A 1/16" bit fit into the hole from the venturi side and could have helped keep the adjuster in place while drilling
6. Might have tried to use the set screw to hold the adjuster from rotating if I only had right hand drills

In the last photo the damage to the threads is the damage done by the set screw
All in all a good outcome.

I still want to try the ALUM method , I even bought some from the grocery store. I saw a different you tube video that looked like it would work

 

[Dana67Dart]

I have a AFB carb with the same problem! What carbs had those limited adjusting screws?

I PMd you about your carb

 

[Dana67Dart]

Well i found a local guy who had a parts carb with two adjusters. The needles are larger in dia but the rest is identical. They came off a 9000 series number carb