harleyKmodel

This post is inspired by the request from wb56 for a 24810-52 upper crankcase stud. Looking through some drawers I came across four crankcase studs. One shorter and three longer studs. The parts book calls out a 4-5/16" length for all K models. The bottom one in the picture had acorn nuts on each end and a 1/32" copper washer for both sides. This one measures exactly 4-5/16". I am assuming this is an original K Model stud. The other three are the same diameter but are 4-9/16" long with a short machined area on one end. They are both 0.278" in diameter. I have a bare set of early K Model cases. Across the cases where the stud goes measures 3-7/8". When I put the 4-5/16" stud through there with 1/32" washers on both ends you only have 3/16" of usable thread sticking out of each end. That's not very much. With the longer studs if you bottom out the acorn nut on the machined end and stick it through the cases with washers you get 9/32" of usable thread sticking out. That seems more acceptable then the 3/16" with the shorter stud. I believe these longer studs would work fine for a K Model application.

A major question I have is, has anybody else seen this type of stud? Was this a revised part without a part number change? Could they have changed when in 1956 they added the 27434-56 carb. support nut?

If anyone has any insight or comments on the subject would love to hear them.

Stan

Looking at the parts book, it calls out 4-5/16" length however, my 56 KHK has the 4-9/16" length stud with machined end.

I believe your image has a 24810-57 stud on top and a 24810-52 stud on the bottom. The slightly longer -57 stud would be needed for the XL engine where the K Model bore of 2.75” was increased to 3.00” for XLs. The K Model stud should be ¼-28 thread and the XL stud should be 5/16-24.

The -57 stud is approximately 5" and is larger diameter, .310" or so.

wz507, that's what I thought at first to and I actually gave them to Roger. We figured out that the 57 stud is a completely different diameter and length. (See Promod117 pictures) Roger sent them back. Thanks Promod117 for the great pictures.

Stan

Attached are a couple of pictures showing what sticks through the case when you bottom out an acorn nut on one end of 4-5/16" and 4-9/16" stud. In my mind the short stud would have required an assembly worker to have had to center the stud in the cases to get the same amount of threads sticking out both sides. And even then you only got 3/16" of usable thread. Bottoming out an acorn nut on the 4-9/16" machined end and slipping it through the case would have given a consistent 9/32" sticking out the other side. With that being said, I find it hard to believe that they used that short length stud for very long. Maybe they used the short stud on the 1952s and quickly figured out that the short stud was not a great engineering design? This is all conjecture on my part because I don't know any better at this point. As I mentioned before, did the length change in 1956 when they started using the carburetor support adapter? My guess is it changed earlier then that. If someone has a 1953,1954 or 1955 K motor that they have access to the upper stud it would be great to hear what length stud is in it. Jerry R., you've been around many K motors in your time. Any insight????