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Carburetor sillyness?

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100DashSix

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My SUs seem to have some funny looking idle screws. One is a flathead, and the other is a stripped (how the P.O. did this is beyond me) Phillips head screw (photo included), each of them stuck through nuts. I don’t know why they’re setup like this, as the nut doesn't seem to stop the screw from being pushed upwards, which un-synchronizes the carburetors. (And which has thwarted today’s tune-up attempt!)

Do the proper screws include springs to keep tension on the screw (like my Healey’s SUs), or is the idea of having a nut the right one? What is the proper thing to replace these with? I’d really enjoy screws that stay where I screw them to.
 

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Dan, if you have the HS4's, they had the tension spring on the idle screws. I'm not sure about the HIF's.
Looks like your DPO got creative.
Jeff
 
I suppose I should've mentioned that. They're HIF-4s. The Moss Motors online catalog describes jam nuts for the idle screws, but the small illustration makes it look like another screw.
 
I have that idle on my carb. The screw needs to be threaded into the plate on the bottom and the jam nut holds it in place. There should be one like that on the high speed idle adjustment, too.
 
So the nut in the photo is correct? I'll look for a similar screw then, one that isn't stripped. I can see how it should work, the nut putting pressure on the screw so it can't wiggle loose, but it doesn't seem to work well. I'll try it tomorrow, though.
Thanks.
 
Definitely a lock nut. Make sure you hold the screw steady with a screwdriver (if it isn't beyond that particular tool already) then loosen the nut with a small wrench. Make your adjustments and then repeat process to tighten. Pretty common setup on old Ford carbs.
JC
 
After you've got it set the way you want, go "find" some nail polish, colour of your choice, and dab a *bit* on the screw/nut/lever as insurance and tell-tale... it'll melt off with thinner or acetone, and is less trouble to break loose than LocTite.
 
Ah, in my defense I posted the picture of the idle screw that was the correct one for the car to have. It turns out the one with the stripped head works fine with the jam nut, but the one on the other carburetor is just a standard metal screw with a useless nut on it.

Can't wait for a tiny packet of screws and nuts to get here from Moss Motors!
 
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