If that is the case, then change this dimension.
The other dimensions above will still work.
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View attachment 163864
Hi green twinThis is what a typical D-valve looks like.
I did a flat design for you.
You really don't need a domed design like is shown in this picture.
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View attachment 163861
In my engines case
How is the d valve attached to rhe rod?
On the pic you got threads and nuts
I got a blank round.
Regards chris