mixture adjustment screws frozen

[odie1]

well i guess i screwed the pooch.....

I was going to do the shotgun cleaning on my carbs and all the mixture screws are frozen. with much PB Blaster and much more force I got 2 of the screws loose.

But the other two screws started to chip. The edges of the slot in the screw head is chipping. Well, it is soft brass.

Anyway, time for the "easy out" screw extractor...well the extractor broke off in the pilot hole I drilled in the head of the mixture screw....that thing is really frozen.:bang head:

Unless someone knows another way to remove a siezed mixture screw i guess I'm screwed....

Hopefully I can just leave it be and hope that the setting it's frozen at is adequate and that it's not clogged and plugged at the needle end cause I ain't gonna be able to clean that passage now.

 

[Saml01]

I was working on a TonyG's yesterday and he has a frozen mix screw as well. His didnt have a head left so I drilled it for an extractor and it threads in perfect but refuses to budge the screw. When it comes to brass, I dont think an extractor will work. Brass is soft and the extractor exerts outward force on the brass which just lodges harder against the cylinder its in.

 

[odie1]

I would have figured the pilot hole in the brass screw would have stripped out before the extractor broke. I'll see if I can get the other stuck screw free and probably clean what i can the best I can and see if it will at least run better.

don't the mixture screws just affect idle air/fuel ratio anyway? Are they not even a factor after you start to open the throttle a bit?

 

[gamorg02]

sean can get them out. not sure if he can with an extractor in it tho!

 

[gamorg02]

I would have figured the pilot hole in the brass screw would have stripped out before the extractor broke. I'll see if I can get the other stuck screw free and probably clean what i can the best I can and see if it will at least run better.

don't the mixture screws just affect idle air/fuel ratio anyway? Are they not even a factor after you start to open the throttle a bit?

they are a factor even at WOT, just not as much. but as high as 15%

 

[Saml01]

don't the mixture screws just affect idle air/fuel ratio anyway? Are they not even a factor after you start to open the throttle a bit?

Since all the circuits in a carb are cumulative as you open it up, if something isn't working its going to affect everything after it.

 

[tugla]

man that sucks. give sean a call but with you already drilling them its gonna be harder.

i spent a lot of time on one once, ended up drilling with a #60 bit but you cannot go all the way thru as the circuit is smaller then even a #60 bit. i drilled til the top of the mixture screw was gone and the spring/oring came out, the the #60 bit by hand to free up the rest of it and go tit out. got to be real care full and stay in the center.

 

[odie1]

well the tip of the extracor bit is stuck in the center. I'm trying to pick at it to pop it out so I can drill out the entire mixture screw.

I can try drilling around the broken bit but will probably end up cutting into the treads on the carb body...unless i can do it with a really really tiny bit.

 

[Saml01]

Not going to happen. Trust me. I have dealt with broken extractors in the past.

man that sucks. give sean a call but with you already drilling them its gonna be harder.

i spent a lot of time on one once, ended up drilling with a #60 bit but you cannot go all the way thru as the circuit is smaller then even a #60 bit. i drilled til the top of the mixture screw was gone and the spring/oring came out, the the #60 bit by hand to free up the rest of it and go tit out. got to be real care full and stay in the center.

This is a great idea, I didnt think to do this but it makes a lot of sense.

 

[odie1]

a previous owner had the plugs removed so I guess water has gotten it over time and caused the spring to rust....but the carb body is aluminum? and screw is brass and they don't rust.

 

[one2dmax]

Yea, I have a pretty good record for getting them out but it's not going to be easy with an extractor broke off in it. I've done it before and had luck but won't know until I try. It's easier if no one messes with them but I know most people want to try.

Sean

 

[tugla]

a previous owner had the plugs removed so I guess water has gotten it over time and caused the spring to rust....but the carb body is aluminum? and screw is brass and they don't rust.

the spring is metal and they corrode and stick to the aluminum a bit.

 

[odie1]

well I'm gonna mess with it a little more but most likely will have to bit the bullet and pick up a used carb or at least a used carb body and write it off as a lesson learned about mixture screws...

even if I get the screw out the threads in the hole will never be right again and I probably won't be able to correctly adjust the mnixture.

 

[Saml01]

How much does one carb go for?

 

[one2dmax]

The threads don't have to be 100% perfect. We do have a tap to run through the hole to clean up the threads. Even a small gouge up the sides of the threads haven't been too much of an issue before.

Sean

 

[one2dmax]

Right side is $150 bare. Left side is $75 (since they don't need to be replaced as often).

Sean

 

[sdt354]

Not going to happen. Trust me. I have dealt with broken extractors in the past.

+1 on drilling an easy out, very hard steel, that's why they're brittle. Might want to get to a good machine shop, they might get it out or drill a good center and drill right through if need be. I've seen carbs that had the lower part of the idle mix. wells ground away to get vise grips on. I'd do it IF I had to. Callling Sean is a good idea too.
Steve-o

 

[one2dmax]

not much sense in calling. Ship it here. I'm either going to fix it or screw it up well beyond repair. No charge if I screw it up (though I can sell you a carb body). $50 if I get lucky plus a new A/F screw ($5) and return shipping ($10).

Sean

 

[satariel666]

Yea, I have a pretty good record for getting them out but it's not going to be easy with an extractor broke off in it. I've done it before and had luck but won't know until I try. It's easier if no one messes with them but I know most people want to try.

Sean

I have 100% record for now LOL - found a very good way to do that - at the same time Im skilled a "little" with machining so cant say its easy.

May talk about it someday....

 

[odie1]

will have to see if I can even get it to run with the screw all dicked up. I don't think it budged at all. But I don't think I drilled all the way thru either so it prob not leaking air from the outside. I'll see about cleaning out all the other jets and ports and orifices on the rest of the carbs and put it all back together and see what happens.

what's really frustrating is it ran ok, not great...just OK, before i did the valve adjustment...just some intermittent high missing and stumbling....it was in storage for 3 years when i bought it. immediately after the valve adjustment i could not even get it to fire or start without lots of starting fluid...