Accelerator Stop Screw Stripped

[Button]

Here's a bit of a problem. After successfully installing a new intake boot to repair an air leak, I wanted to set my idle properly. My spider was idling around 500 rpm which is low for a 5spd. Using Brad's guide I fully set the idle screw, but when I went to tighten the accelerator stop screw to raise the idle, I found that either the screw or its housing is partially stripped. The bottom 1/4 inch will screw will hold against the spring pressure of the throttle, but beyond that, the throttle will push the screw straight through the threads.



This photo is my best effort at illustrating my problem. I had tightened the screw to the point where the lock nut was flush with the housing, but when the throttle pressed against the screw it "popped" back to this position.

I'm hoping that it is the screw that is bad and not the housing, because that seems like much less of a hassle. Does anyone have a good suggestion on where to source a replacement screw? Any thoughts on what I should do if it's the threads on the housing that are bad?

[wizard124]

Looks like you have room on the stop end of the screw to fit a jam nut. Easiest work around I think.

If the flange is stripped, drill out and tap the next larger size. A bolt could have its end ground down to make the stop.

[Button]

Thanks for the suggestions! I didn't know what a jam nut was and was puzzled for a minute, but then I remembered that Wikipedia knows almost everything:

Jam nut

This may be a bit of a first grade question, but how can you tell if a nut is threaded in such a manner that it will be compatible with your existing bolt?

[johnsje6]

Take your bolt to the local hardware store, or home supply big box store, they can fix you up with a correct sized jam nut, or a tap and a larger bolt.

[Button]

I've installed a new accelerator stop screw, and it appears to fit well.

I went to the local home depot and bought a new bolt and nuts that compared well to the dimensions of the original bolt and nut. The bolt I bought was sized 6mm-1.0 x 25mm and seemed quite close to the original size and thread spacing.

The install was relatively easy using 10mm wrenches and sockets. I can now start the car when it's cold and have the engine idle high enough to keep running, although I'll have to wait until the weekend to get her warmed up to properly set the idle.

[KevAndAndi]

So which threads were stripped? Or was it a combination of both the bolt and the hole?

[Button]

It appears that the threads on the original bolt were the problem. They wouldn't hold in the hole, but the new bolt does. So far I'm going to try using a nut on either side as a bit of a "belt and suspenders" approach to keeping the new bolt in place, and some of the pressure off the threads.

[KevAndAndi]

It appears that the threads on the original bolt were the problem. They wouldn't hold in the hole, but the new bolt does. So far I'm going to try using a nut on either side as a bit of a "belt and suspenders" approach to keeping the new bolt in place, and some of the pressure off the threads.

That sounds prudent. And one shouldn't have to make frequent adjustments to the idle stop screw - if one does, then there's something wrong.

(As an aside, I do have something wrong and have to make adjustments to that screw. The RPMs plunge a few seconds after starting, and so I move the idle stop to keep it idling. After it warms up, it's fine, and I return the idle stop to the normal position. I could just rev the engine with the accelerator, but I'm lazy. Anyway, that's why I was curious about the fragility of the threads.)