[700rpm]

I had a similar problem with an engine rebuild four years ago. Car would overheat and lock up when stopped, until it cooled down. Tried different rings. Checked ring clearances. Reassembled. Still stuck. After much discussion with the machine shop (very reputable), we determined that in spite of boring and honing to mfg specs, the pistons and rings were too tight. We pulled the engine for the third time, rehoned and increased the piston to wall clearance to .0045. Problem solved. Pistons and rings were from Snyder’s. Not their fault, the mfg specs were to tight.