Question about the RR-1 Valve

It should, not really a load bearing part. I was more concerned about the hole for the crank pin wearing.

If it ends up lighter you may see a performance gain.

Cribbs74 wrote:It should, not really a load bearing part. I was more concerned about the hole for the crank pin wearing.

If it ends up lighter you may see a performance gain.

This is a very nice piece of machining and is to be commended.

The "hole" will not be an issue. I have use aluminium, duralloy, nylon, ptfe................. for disc valves. They become an extension of the crankshaft and the lighter they are the less stress there is around the hole. Not that there is much around the hole anyway.

However (there is always a "However"), the Cox valve is a rotary valve and rotates around and against the "bearing" on the tank. Dependant upon the grade of aluminum, the aluminium usually "work hardens" but this is the area to be wary of.

The RR1s I have repaired look as if the damage (pin breaking off, breaks around the hole in the valve) has been caused by a seizure with the valve to tank contact.

"aluminum is much easier and nicer to machine" - Not really! It may appear so because it is quicker but a very fine finish straight from a lathe is difficult.

I ALWAYS buy a known grade of aluminium. My material of choice is HE 30 TF............ 6082 T6 or T4. It machines beautifully but requires the cutting tools ground to special angles and I use paraffin (kerosene) as a lubricant. Other grades of aluminium "stick" to the cutting tool and don't machine freely. The finer the cut the harder it gets.

Perservere with free cutting steel. Practise makes perfect!

ian1954 wrote:

Cribbs74 wrote:It should, not really a load bearing part. I was more concerned about the hole for the crank pin wearing.

If it ends up lighter you may see a performance gain.

This is a very nice piece of machining and is to be commended.

The "hole" will not be an issue. I have use aluminium, duralloy, nylon, ptfe................. for disc valves. They become an extension of the crankshaft and the lighter they are the less stress there is around the hole. Not that there is much around the hole anyway.

However (there is always a "However"), the Cox valve is a rotary valve and rotates around and against the "bearing" on the tank. Dependant upon the grade of aluminum, the aluminium usually "work hardens" but this is the area to be wary of.

The RR1s I have repaired look as if the damage (pin breaking off, breaks around the hole in the valve) has been caused by a seizure with the valve to tank contact.

"aluminum is much easier and nicer to machine" - Not really! It may appear so because it is quicker but a very fine finish straight from a lathe is difficult.

I ALWAYS buy a known grade of aluminium. My material of choice is HE 30 TF............ 6082 T6 or T4. It machines beautifully but requires the cutting tools ground to special angles and I use paraffin (kerosene) as a lubricant. Other grades of aluminium "stick" to the cutting tool and don't machine freely. The finer the cut the harder it gets.

Perservere with free cutting steel. Practise makes perfect!

The finish won't be an issue. I intend to polish the "bearing surface" of the part today. We have a tool for polishing crankshaft journals. Should do the trick!

And here it is!




Installed it both ways and everything turns freely and smoothly. Hopefully will get a chance to test it out soon.

Looks like a winner!

Let us know how it runs, or better yet get video