Intake tube torque spec

[TheTurtle]

one of my intake tubes has a loose nut.  I cant find an exact torque spec for it. 

I did find in the lycoming overhaul manual on the service table limits section for all bolts and nuts listed by size of bolt/nut.

http://www.expaircraft.com/PDF/Lycoming-OH-Manual.pdf   page 142

7/16 = 50 ft/lbs

1/2 = 75 ft/lbs

what I wasnt sure of is it says thats the thread size.  So is that NOT the size of the socket Im using and actually the size of the threads?

[Guest]

1 hour ago, TheTurtle said:

one of my intake tubes has a loose nut.  I cant find an exact torque spec for it. 

I did find in the lycoming overhaul manual on the service table limits section for all bolts and nuts listed by size of bolt/nut.

http://www.expaircraft.com/PDF/Lycoming-OH-Manual.pdf   page 142

7/16 = 50 ft/lbs

1/2 = 75 ft/lbs

what I wasnt sure of is it says thats the thread size.  So is that NOT the size of the socket Im using and actually the size of the threads?

The intake tube hardware is usually 1/4-20 NC thread and torqued to 100"lbs.. An easy way to figure out bolt size is to take the wrench size in 1/16's less 3/16" to arrive at bolt diameter.

Clarence

[TheTurtle]

Just now, M20Doc said:

The intake tube hardware is usually 1/4-20 NC thread and torqued to 100"lbs.. An easy way to figure out bolt size is to take the wrench size in 1/16's less 3/16" to arrive at bolt diameter.

Clarence

So I think the socket size for that bolt is 1/2".  1/2" - 3/16" = 5/16  (pretty close to your 1/4")  The book says 1/4 = 96 inch lbs.

looks like your math checks out   thanks!!

[Guest]

3 minutes ago, TheTurtle said:

So I think the socket size for that bolt is 1/2".  1/2" - 3/16" = 5/16  (pretty close to your 1/4")  The book says 1/4 = 96 inch lbs.

looks like your math checks out   thanks!!

In 30 plus years I've never seen anything but 1/4"-20 NC on an intake.

If it has a nut which requires a 1/2" it may be the exhaust stacks you're looking at.  If so these are 5/16-18 NC threads.

Clarence