Leak down thoughts, manometers.

Well Ted lapping the flats of the rings of course. Grinding the OD of the rings to match the ID of the cylinder bore with a torque plate in place. We also experimented with Surface texture and the face angles until we found what we liked.
I’m not a fan of barrel faced rings. Even in a perfect world they leak on initial pressure and vacuum. The engine will be smoother because of that but blow by is up slightly and power suffers full range due to compression leakage and lack of intake vacuum.

Best, WP
 
Well Ted lapping the flats of the rings of course. Grinding the OD of the rings to match the ID of the cylinder bore with a torque plate in place. We also experimented with Surface texture and the face angles until we found what we liked.
I’m not a fan of barrel faced rings. Even in a perfect world they leak on initial pressure and vacuum. The engine will be smoother because of that but blow by is up slightly and power suffers full range due to compression leakage and lack of intake vacuum.

Best, WP
Maybe you misspoke about the ring to cyl grinding... that is the job of the surface finish by a hone on the bore. In the old days it was not uncommon for somebody to dump a container of comet cleanser in a motor to re - hone the cylinders so they thought.
 
Thanks for the observation CH but the statement is correct. We built a fixture to hold the rings with the gap closed and ground them to exact size on an Cincinnati Cylindrical Grinder. This allowed us to adjust the surface texture and contact angle of the ring face. Many builders have had these fixtures for decades. Waiting for the cylinder surface or toilet bowl cleanser to finish the ring seating process is not my idea of a high precision engine build.
Back to Ted's question, after the rings are ground we file fit their gap. An aluminum bore .003" the IC or metal bore .004". After 700 laps they would be in the order of .006" gap with little to no cylinder ware. Keep in mind this is in the old Briggs flat head engines. All this fine precision is for nout if the block has impurities and air pockets in the casting which was common in these industrial purpose engines.

Best, WP
 
Thanks for the observation CH but the statement is correct. We built a fixture to hold the rings with the gap closed and ground them to exact size on an Cincinnati Cylindrical Grinder. This allowed us to adjust the surface texture and contact angle of the ring face. Many builders have had these fixtures for decades. Waiting for the cylinder surface or toilet bowl cleanser to finish the ring seating process is not my idea of a high precision engine build.
Back to Ted's question, after the rings are ground we file fit their gap. An aluminum bore .003" the IC or metal bore .004". After 700 laps they would be in the order of .006" gap with little to no cylinder ware. Keep in mind this is in the old Briggs flat head engines. All this fine precision is for nout if the block has impurities and air pockets in the casting which was common in these industrial purpose engines.

Best, WP
thanks. i will lay awake half the nite thinking about all this.
 
It must have been quite a project to build a fixture to hold rings to machine them to the required precision. Would you mind sharing a photo?
 
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