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Engine basics => Engine set up tips => Topic started by: Dan McEntee on June 14, 2021, 09:21:23 AM
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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.
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.
Just posting this here as he is busier than a one legged man at a butt kicking contest trying to get things straightened away for the NATS and I'm trying to help him out.
Thanks in advance,
Dan McEntee
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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
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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
Remove the head and tell David that it somehow fell off during the 2400 mile trek to Muncie. ;D ;D ;D
Dennis
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Hi:
Eleven inch pounds is correct for a 4-40 screw and an aluminum hole.
Good luck,
Frank
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Inch Pounds or Inch OUNCES ! Id say In. Ounce . about 1/4 or 1/3rd of a full fingertip push ! Farmers fingers . Bout 1/2 a city fingertip push . S?P H^^
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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.
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.
Just posting this here as he is busier than a one legged man at a butt kicking contest trying to get things straightened away for the NATS and I'm trying to help him out.
Hi Dan
Use 10 in lbs for the head, and about 8 for the backplate, the shims should start at 15 thousands, that is the stock setup. The head bolts are 4-40 x 5/8 and need to be a high strength bolt, please do not use stainless as some have
The PA has a T flange sleeve so there is no bending of the lip of the sleeve
any other questions just ask or email
Randy
Thanks in advance,
Dan McEntee
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Inch Pounds or Inch OUNCES ! Id say In. Ounce . about 1/4 or 1/3rd of a full fingertip push ! Farmers fingers . Bout 1/2 a city fingertip push . S?P H^^
Inch-pounds
Brett