Ok guys I have tore into a mid 1925 engine. that has low compression. was going to check the valves and as I went to remove them I found that the Valve stem was threaded. This caught me off guard. they have a lock nut that screws on the stem and has a threaded cap which meets the tappet. so these are adjustable but I have not seen a set like this. not a threaded valve stem anyway. I am sure these are not original for 1925.
Threaded valves may have been sold as accessories back in the day for easy valve adjustment when you didn't want to cut the seat deeper to decrease the lash. Installing adjustable lifters takes more time and work.
Here threaded valves are discussed combined with another more exotic accessory, multi lifts: http://www.mtfca.com/discus/messages/118802/154162.html
I wish someone would sell dies for cleaning up the threads on tire valve stems!
Larry, Good auto parts stores have a small tool that has the inner and outer tap and die for tire valve stems. I've had one for years, think it is a 4 way tool. I'll have to take a look to see if the is a makers name on it.
Milton makes about any quality air chuck, valve stems, four way tools or any thing in that line. KGB
Here is the tool that Tim was talking about, mine has no maker's marks that I could find.
Is everybody reading carefully?
Yes Steve, simply a little thread drift. KGB
It's all Larry's fault! I just followed along with the drift...
That tool could make it have low pressure ( Compression ).
That's the tool. Sorry Steve. Add another black mark for me.
Keith, that last one was horrible! We need to chase you out.
Spent yesterday chasing threads all over my shop, damn they sure are fast little devils. Never did get em' all
Larry, do you mean the larger threads on the outside of metal stemmed valves?
Allan from down under.