Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

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?

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!

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.