[marco]

Hello all,

When you are going to put in new pistons and the old ones can be trown away there is another trick which I used succesfully on a Cadillac 346 flathead Chaffee engine (after many alternatives failed):

Select a piston of which you are sure it is stuck.
From the top, drill a hole about 6mm diameter at the edge of the piston at a safe distance of about 10mm from the cilinder wall.
You might have to make an extension for your drill bit to have sufficient reach.
Drill as deep as you can get checking carefully not the hit the cilinder wall.

Once your through, replace the 6mm drill with a slightly larger drill and repeat the job, again checking carefully not to hit the cilinder wall.

The trick is to try to drill a hole as large as possible.
At a certain moment the wall of the piston is weakened enough to remove the tension between piston and cilinder wall.
Try to turn the crankshaft to see if it is coming free.
If not, pick out another stuck piston and repeat the job.

The method seems quite unconventional, but if done accurately it really works.

Marco