I'm asking for a friend who needs some information. We would like to know what the torque value is for the head bolts on a PA-75. I think they are a 4-40 but I'm not sure. He has one of those small tools for setting such fasteners, just has never needed to use it before.
That is a Randy question for sure, but a little research and I found a typical range of around 10-11 in-lb. That appears to be based on how much elongation/tension you get in the bolt. Sounds a little high to me for tapped aluminum - I would certainly not exceed that. Part of the tension is going to be supplied by deflecting the head, since there is some unsupported length.
Also, what are the thicknesses of the head shims that most PA-75 operators use? I have the tools and materials to make them but would lie to know what thicknesses are typical.
.003, .005, and .008 are typical shim dimensions, you want more, stack them. As to what you need, it depends on how you set up everything else. We should be out at the field on Sunday, hit David up for that.
David's airplane will be in my van Wednesday afternoon, I will remove the head and measure it for you., and maybe "help" him out by adjusting it...
Just kidding, of course.
Brett