Are you going to run on steam or air and if so will the engine just run for display or will you want it to work.

In most cases filling with JBWeld should do but if working hard at high pressure then a Sleeve may be the better option and that can be slipped in with Loctite 648

You will have to either remachine the inlet slot which now looks like it is too wide compared to the good one and may have a job getting a crisp edge to the JBW in which case machining out the whole valve chest deeper and inserting a plate would be the best cure

Also what's going on with the exhaust slot, that looks to be over length for part of it's depth so you may need to widen the valve to get a good seal at the edges or see plate mentioned above

Look at the second photo the slot is much wider than the other as either the cutter has been wobbling about or more likely gone in beyond the parallel flute length and started cutting where it tapers out to the shank diameter so will be a tapered slot and need to be remachined.

I would bore slightly oversized and sleeve the cylinder.

If you haven’t made the valve yet you can make it oversized to cover your ports.
The limit on flow will be the (presumably to do) drilled holes from the ports to the ends of the cylinder, so the imbalance in slot sizes shouldn’t affect the running much.

Dave

By the time you've machined a recess, fitted a plug bored out the cylinder, made and fitted a liner, you'd have made a new cylinder from a lump of iron bar. If you are making a new one make the valve chest a loose piece, then you can see what you are doing when machining the ports

Duncan I totally agree with you but the original poster didn’t mention buying or re making a replacement, he wanted suggestions to repair what he had messed up, I just offered an idea to put both the mistakes right. I would certainly favour a separate steam chest, makes life so much easier.

If you have a look in my album you will see some photos of a similar situation. I had bought a Stuart 10V which had been well butchered. I had to machine out the inlet and exhaust ports and then machined a brass block which was JB welded into place. This worked very well.  The solution was shown in my Resurrecting a Stuart 10V series of posts.

Colin

Edited By Colin Heseltine on 27/09/2021 20:36:06

Edited By Colin Heseltine on 27/09/2021 20:36:42

I think the problem with that will be that once the individual plugs are slotted you will have some quite thin walled oval tubes which may crumble. Would be easier to mill out a rectangle and bond in one single block say 3mm deep.

Also when you come to mill the new slots check you don't have too much cutter sticking out of the collet as that may have been part of your initial problem trying to reach down into the chest, a long series cutter would be safer.