I have been trying to adjust the timing on my Stuart #4 and I still have a bit of a knock. I discovered it is coming from the rod moving a bit on the eccentric sheave. If I tighten the rod down a bit it seems to go away, but the engine turns much harder. How tight should it be? Do I have to accept a little knock?
You are up against the finer nuances of such adjustments I'm afraid. I think the proper condition would be to tighten until there is virtually no "slop", but just short of having any binding.
Of course, part of the equation is the quality of the machining, as slight roughness of the mating surfaces will require more tolerance in the tightening of the collar around the cam. A fairly heavy grease could offer some dampening of the knock, while adding lubricity so that increased tightening could also be achieved without too much added friction.
Ultimately, lapping may well be the answer if this is the case, so that the collar can be further tightened without producing undue friction.
Thank you for the help. The machining is very good. I think I am being too picky. I have is set on a plastic folding table that seems to amplify the sound. I am going to learn how to post a video so you all can see what I am talking about. I have been watching Keith Appleton’s videos for a while. He prefers that the timing be set so that there is a bit of early admission of steam or compressed air to cushion the piston. He also said on larger beam engines that the steam/air is retarded a bit to achieve slower running. What should I be aiming for? Early or late? I just don’t want to damage anything so I need your advice on this as well. Thank you all for your input and patience with me.
Video came through just fine and the knock is quite obvious at certain speeds. I agree that knock is more than you should need to accept on an engine that appears to be that well-built.
I wonder if you can slow the video down (slow motion) to get a more accurate idea of exactly where the knock is occurring?
Have you tried simply wiggling the various linkages with your hands under static conditions to see if you can detect excessive movement?
You say tightening the rod makes the knock go away, but also stiffens the engines rotation. However, even making the engine harder to turn, does it still turn over under moderate pressures? If so, perhaps that is what you need to do to get the engine to "wear in" and run quieter, which will probably also slowly free up the motion for the future!?!?
Perhaps the slightest dab of really fine lapping compound on the offending contact surfaces (if they have been truly identified), would be of benefit to the eventual elimination of the knock and the binding?
A beautiful engine like that deserves to run smooth and quite at all speeds, so hopefully you will find the combination of settings that will bring about that desired result!
I just adjusted the timing more “aggressively”. Meaning I moved the sheath round the shaft further. That seems to have eliminated the knock. I opened the steam chest to make sure the valve was in the center and it was. I decided that I wasn’t adjusting the timing enough. It has quieted down. I’ll do another video in a while.
Hey, that sounds like a far better approach/solution!
Great work!!!
Hummmm
Looks like it is more a case of lateral slack rather than circumferential slack. I wonder if the upper valve rod and lower valve rod are in true alignment. Perhaps the cam needs to be moved laterally along the shaft slightly if that is even possible.
It seems that the engine runs dry - you should oil all bearings with a good motor oil
such as SAE 40/50. This is what is used in old cars that still have bronze bearings.
The "Stuarts" need good and sufficient lubrication otherwise the bearings/shafts start
knocking.
Arnold
