Idle Screw screwing out (3 Viewers)

[faalkinaey]

So I once again need the help of this forum, (huge thanks to the forum) my fj60 carb Idle Mixture screw (not idle speed) keeps screwing out, it’s perfect at 4 turns out but after driving the setting gets messed up. I’ve read that applying blue loctite to the threads of the screw is a solution but I was thinking wouldn’t it get sucked into the passages and gum things up? I also can’t seem to find a replacement screw (or spring). What are some advisable solutions to keep it from turning out?

 

[bhsdriller]

I assume it has the spring on it?

 

[Spike Strip]

I dunno - loctite, blue or otherwise, is the last thing I'd want on a mix screw. I suppose it could migrate to the idle circuit passages, then you'd be f'd.

It's most likely backing out because the spring is broken or missing. The NAPCO Carb kit will have a new spring, though the mix screws included won't work. The Keyster doesn't have the spring.

Kits are available on fleabay from Indonesia or Middle East sources.

 

[faalkinaey]

I assume it has the spring on it?

Yes, probably just lost tension. Would any generic home depot spring kit work fine? These springs don’t need a “certain” tension for it to work right?

 

[mattressking]

Post a photo of the mixture screw in use and spring. USA 80-87 is different from the ROW carb mixture screws and only one I have found works in place of it.

 

[faalkinaey]

Post a photo of the mixture screw in use and spring. USA 80-87 is different from the ROW carb mixture screws and only one I have found works in place of it.

 

[faalkinaey]

Maybe a lock washer sitting between screw and spring could do it?

 

[mattressking]

Measure length of spring and measure overall length of mixture screw.

The mixture screw is correct, just easier to confirm all of the dimensions.

 

[cps432]

I dunno - loctite, blue or otherwise, is the last thing I'd want on a mix screw. I suppose it could migrate to the idle circuit passages, then you'd be f'd.

It's most likely backing out because the spring is broken or missing. The NAPCO Carb kit will have a new spring, though the mix screws included won't work. The Keyster doesn't have the spring.

Kits are available on fleabay from Indonesia or Middle East sources.

Loctite is essentially cynoacrylate with additives to prevent adhesion at different torque loads. In laymen’s terms it’s retarded superglue.

Once it cures it’s solid. If you add a dab to the threads and let it set up it will never move or migrate.

If you know that 4 turns out is where you want it and it’s happy then loctite it and back the screw out to where you want it and let it set up for a half hour and you’ll be 100% fine.

 

[cps432]

View attachment 3949859

Clean that thing up nice and try loctite. Get the heavy gel type stuff if you have qualms about it migrating while you’re getting it setup. If you know 4 turns is it then loctite it. Set it. And forget it.