Roundhouse valve timing

[Big Jim]

My Billy has misbehaved the last twice I have run him. It is absolutely gutless. The first time I thought that the link to the regulator had slipped and so it wasn't opening far enough. This was adjusted but it appears to have made no difference.
There is plenty of pressure on the gauge and plenty of exhaust steam but no oomph.
How far out would the timing have to be to cause an issue?
One crank appears to be ever so slightly out? I am talking about a gnats whotsit.
I don't really want to go for a full strip down as I really haven't got the time, but I suspect I might have to.

[TonyW]

If the wheels are going round without any obvious dead spots (struggling to pass a particular point in rotation) then it is almost certainly not valve timing. More likely to be regulator or superheater problem.

If the wheels do have a dead spot then the answer to your question is: Not much.

[Keith S]

The guy who makes the "Slomo" device has some videos on YouTube, in one of which he shows a great way to adjust timing and get it perfect. You should watch it.

It doesn't have to be out too much to deliver poor performance. If the cylinders aren't in sync, there will be some point in the wheel's rotation where they are working against each other, or at least not helping each other...

Also I find the sound of poor timing unbearable, like a square wheel.

[pandsrowe]

I had a very similar issue with my Billy a while back which seemed to have suddenly happened. There was me thinking total rebuild or returning to R/H for complete overhaul etc. Turns out that I had inadvertently knocked one of the trim tabs on my transmitter and even when the stick had been moved to regulator fully open there was virtually no steam getting through to the cylinders.
Although if your Billy is a manual version this idea is not going to be much use!

[DLRdan]

Is there any beat to the exhaust or is it constant flow of steam ?

[Big Jim]

Hmmm.
Not sure about that Dan but it has got me thinking. If it was a flow rather than a beat that would suggest timing.

[laalratty]

If steam appears to just be blowing up the chimney with poor performance then it could be the piston rings.

[DLRdan]

As Christopher has said, a flow from the chimney would suggest either the piston rings are no longer sealing or for some reason a valve has got stuck off its face. As the valve chest covers are readily accessible on a Billy checking to see if the valves are off the face or the timing is out shouldn't take more than a few minutes.

[artfull dodger]

If Billy has lots of hours of run time, it might be time to refresh the cylinders. Roundhouse has a kit for this that isnt very costly and includes all the necessary bits to do the cylinder refresh. And they are correct, its a quick check to see if the valve timing is correct once the top plates are off the cylinders. To me is sounds like blow by inside the cylinders, poor sealing in either direction in the cylinder bore would make the engine gutless. Mike

[artfull dodger]

You can test without tearing down, put the valve gear in neutral and open the throttle, if steam goes up the chimney, then the slide valves are not seating (or timing is slightly off and one or more ports are uncovered) and allowing blow by. If Billy passes that test, then its most likely worn pistons and a refresh is in order. Also if Billy has lots of run time, check how much "slop" there is in the motion. Over time the side rods and valve motion will wear out and need replaced as well. This is why we all love Roundhouse...parts support so we are not afraid of running our little beasts to our hearts content. When I reset the timing on my Sammie that I put normal valve gear on instead of the slip eccentric. I take the top covers off and put them back on with just the two outside screws keeping the internals of the slide valve open to view. This keeps the valve chest in place on the cylinder, and the top plates from laying on the bench and picking up grit and grime. I then adjust slide valves so I have equil views(uncovering)of the ports in the valve block when I rotate the drivers. I do one side then the other. Once both sides are equil, reassemble everything and then raise steam and see how model performs on blocks first, if all seems ok, try on the railway, first with just light engine, then with a load. If the cylinders are healthy, you should have enough power to stall Billy and slip the drivers. If not, then its time to remove the cylinders from the model and refresh them with the kit from Roundhouse. If any valve motion or side rods have excessive play, its time to refresh them as well. Just like the real beasts, an overhaul is needed from time to time if run enough. Mike

[Big Jim]

I may have sorted the problem out. I had a good look at everything and ran it on blocks. It seems that the regulator was still not opening enough on the RC. This may have been due to the O ring one the spindle not being seated properly. So although there was enough movement on the arm, the O ring was still restricting the passage of steam.

[GTB]

I may have sorted the problem out. I had a good look at everything and ran it on blocks. It seems that the regulator was still not opening enough on the RC. This may have been due to the O ring one the spindle not being seated properly. So although there was enough movement on the arm, the O ring was still restricting the passage of steam.

FWIW. When I had r/c fitted to my Bertie based Hunslet, I found the o-ring on an r/c regulator had a tendency to stick if the loco was left for a while between runs and would then be pulled off the tip of the spindle when it was first opened. I started leaving the regulator half open when putting it away and this seemed to improve things.

Regards,
Graeme