Wanting to be reasonably "correct" in reassembling my 1915 roadster, I've been looking at manifold and valve cover studs and bolts.
Here they are. Manifold stud: 3/8-24 x 3 3/16"; Valve cover stud: 3/8-24 x 2 29/32"; Valve cover bolt: 3/8-24 x 2 29/32". You can see that the studs are the same except for the length and the amount threaded. If you have extra manifold studs and need a stud for your valve cover, it's easy enough to adapt one.
Now we get to the "correct" part.
Lang's shows the manifold stud for 09-25, with a bolt for 26-27; Chaffin's shows 09-27 for the stud; Mac's, stud 09-27; Snyder's, stud 09-27; Birdhaven, stud 09-27; Bob's, stud 09-27. Obviously, the stud works for all years. I'm assuming that the bolt is correct for 26-27 but most don't carry it. Am I right? Can you cite a source to confirm your information?
Lang's shows the valve cover stud for 11-24, with a bolt for 24-26 and another bolt for 26-27 (a couple of those running changes, no doubt); Chaffin's shows only a bolt for all years; Mac's, one bolt 12-24 and nothing else; Snyder's, nothing; Birdhaven, stud 12-20 and bolt (capscrew) 21-27; Bob's, stud 12-20 and bolt (capscrew) 21-27. Again, I'm assuming that all will work. But what's correct for what years? Can you cite a source?
That’s fairly easy…
Evolution of 3066
3066/T516 was used on the 09-11 @3-5/16” long
3066/T516 (no revision but was probably 3066B) was used on the 11-24 @3-1/4” long
3066C/T516B was used on the 24-26 @ 2-5/8” (used with gull-winged clamp)
3066C2/T4882 was the bolt version used on 27 @2-5/8” from the bottom of the bolt head
Evolution of 3112
3112/T654 was used on the 11-20 @ 3-5/32” long
3112/T654 (no revision) was used on the 20-27 @ 2-29/32” long
As to source, the shown dates are based on Bruce best guess when I set up my database. (Bruce shared his research listing with me when I started the project. How he arrived at his conclusions is much better than I can surmise yet I'd take the source as reputable, realizing that Bruce was always open-minded if and when new evidence came to light.)
The valve cover stud and nut was changed to a bolt in 1920.
Excellent. Thanks, gentlemen. I'm saving this one for future reference.
I've been through that. There are a number of them out there. When you see them, buy them, and worry about the length when you get home! The later T's have a shoulder at the base, so there is no guessing how far you need to screw it in.
One other tid-bit to add to your file.
The 3112/T654 (no revision) was actually a bolt as R.V. points out. I went back and re-looked.
There was also a 3011B used in 26-27, but it was labeled as 3011B/T436 and was a bolt. (The 3011 may be a typo for 3112??) I don’t have a length on that one. (It may be the one that Larry mentions as the T-number is different also?)