M74B screw size

[ldfly112]

Yesterday I was adjusting the low speed needle on my 1961 Panhead . I noticed that I was only turning the screw at the top of the low speed needle the needle was not moving only the screw . I removed the entire needle to inspect and sure enough I dropped the screw on the floor looked for 2 hours no screw to be found. Can anyone tell me the exact size and thread of this screw so I can find a replacement . And for future reference what keeps screw and the needle tight to prevent this again should I use thread locker or just tighten the screw and hope for the best THANKS if you can help

[dukekleman]

IDFLY,

Here's a few images for you. The one image is of an original screw along side a replacement screw from a kit I put together.
The other image is the full description for the replacement screw from my kit box I assembled.
IMG_20260810_065800614.jpg
IMG_20260810_065729957.jpg
I hope this helps,

Duke Kleman

[T. Cotten]

For some reason, Idfly,

The forum will not let me quote you!

Original screws were cad, and average ~.300" or so, just shy of 5/16"

More important is that it was secured to the knob with a split-lock washer that averaged close to .070" in thickness, which is uncommon for modern hardware. (A thinner washer would preload the spring slightly more, but still seems to function to protect the needle tip, when due care is taken with assembly.

....Cotten
PS:
Another common complication is using the proper spring, as some suppliers confused the tighter-wound detente spring with the proper one on the right, when they became scarce.

SPRINGS.jpg

You want to regrind all points, and avoid this:
PTCONTCT.jpg
PPS:
If anyone can decipher the Parts Book numbers for these individual parts, we all would appreciated it.