Cylinder distortion, 1971 2.2T

[67R69S]

I just received a call from my machinist with a concern about cylinder distortion. He measured the cylinders to be round when unstressed, and when he torqued them down under a torque plate he found they were distorted out of round by up to 5 thou of an inch. He is concerned that this is too much. Torque used was 23ft-lbs. We are going to attach the cylinder to a case half using a head to torque it down and we will measure the distortion, if any. Have any of you fellows come up against this and would you consider it normal?

Thanks for any help you can offer, this is kinda out of my league.

Cheers

[docrodg]

Never tried with a 911 engine. Can state with much experience on watercooled engines that distortion occurs rather interestingly, cylinders try to become a pentagram around the 5 headbolts on chevy engines for instance.

Interesting to find out what you measure with it installed on the case, as the spigots and heads could affect it. There was discussion here recently on using a torque plate. With the spigot on one end and the head sealing on the cylinder lip on the other it is much different stresses than an engine that has a flat surface for the head.

Even more interesting would be how they were straight from the factory. Did the factory torque plate them? what were the measurements?

Many years of excellent knowledge on here, especially Henry, Grady, John Walker, Steve, etc. etc. etc. If they chime in it will be very educational as always