A curious noise coming from an overhauled engine

[Shvegel]

It sounds like you found the right mechanic.  I am a mechanic by trade and that was a very strange problem to have.  Happy motoring.

[watson2]

Yess , Shvegel, it seems so . Thank you for the support.

I get to conclusion.
Before ordering the pistons we made a test to check if the reality was matching the theory  .

The mechanic installed the valves with springs to obtain a good sealing.
Then he got some oil into a syringe and carefully filled what was remaining of the combustion chamber .
We were glad to verify that the quantity of cc was exactly 35.

This time the overhaul was really complete and the valve guides were the only details that were conserved .
They were new and in good conditions. Every other detail was changed.

The engine runs smooth and silent and when I look at the front of the car it seems to be smiling.

I hope all this can be useful .
 

[watson2]

During this two years of troubles , I read , I investigate and so I found that , especially on cars coming from the United States,
very often were used these pistons. Probably the meaning of the particular shape is always the same.

We preferred the type of shape we used to have a good and uniform propagation of the flame front.
On the contrary the top of the two inclined surfaces seen in this picture could be an obstacle.

[Cees Klumper]

Thanks for letting us know the final resolution, sorry you had to go through all that extra trouble (and no doubt expense). It reinforces the importance of selecting a rebuilder who truly has the expertise to do these engines properly.