Spook's reply to the recent 30mm NUT post started me thinking about how to apply the high torque to a crankshaft nut required to tighten it to spec.

One way to provide counter-torque to prevent the crankshaft from turning is to insert a length of rope through the spark plug hole with the piston about halfway up on the compression stroke. As the torque is applied to the crankshaft nut, the shaft will turn until the rope prevents the piston from completing the compression stroke. It effectively locks the piston, preventing the crankshaft from turning so that torque can be applied to the nut.

I used this technique recently on my B230 engine with no problems. But I'm wondering how risky it really is, expecially on a 960 engine. I've heard an urban legand that the rope can become jammed in the cylinder wall, requiring the removal of the head. Does anyone know with certainty of any real hazards of using this technique, such as cracking a piston or such?

Thanks,

Robert