T

Tkitchen1

Member
Hello all, Where is the best place to get the small engine parts for Lycomings
such as Cylinder nuts, gears, cam bolts etc.

Thank you for all help
 
If it is a certified engine, it has to have Lycoming STD-XXXX nuts and bolts, and you can get them from aeroinstock or aviall. The part #'s for all nuts and bolts are all listed in the parts catalog for your engine. Believe it or not all of Lycoming bolts are grade 5. If its experimental, just use AN or good quality Grade 8 stuff. Obviously that's better than what Lycoming supplies for their engines. Now if its something like an STD-2209 crankshaft bolt, get that from aeroinstock.com.

You can choose to spend $300+ on OEM nuts and bolts, or buy something better from a reputable hardware supplier like Fastenal, and have better hardware. Again only if its experimental.
 
Internal 12 pt nuts on narrow deck

Is there an option to use something other than the internal 12 pt nuts that are used on the O-320 b3b narrow deck?
 
Not necessarily!

rocketbob said:
Believe it or not all of Lycoming bolts are grade 5. If its experimental, just use AN or good quality Grade 8 stuff. Obviously that's better than what Lycoming supplies for their engines. Now if its something like an STD-2209 crankshaft bolt, get that from aeroinstock.com.
Click to expand...
AN? OK. I wouldn't use a grade 8.
A grade 8 bolt is more brittle than a grade 5.
 
Mel said:
AN? OK. I wouldn't use a grade 8.
A grade 8 bolt is more brittle than a grade 5.
Click to expand...

More good advice from Mel. Grade 5 bolts (500 MPa ultimate tensile strength) are only case hardened. Grade 8 bolts (800 MPa ultimate tensile strength) are through-hardened and as such they are more brittle and therefore more prone to stress fracture.

Fastener technology is a science in itself and it completely freaks me out when I hear of builders using "intuitive" judgement as a basis for substituting specific fasteners as recommended by an engine manufacturer with some alternative fastener.

In the case of bolt grades....more is sometimes less.
 
Last edited:
Tkitchen1 said:
Is there an option to use something other than the internal 12 pt nuts that are used on the O-320 b3b narrow deck?
Click to expand...
The reason they use the barrel nut, is clearance issues between the cylinder barrel and the nut. If you were to use something else, you might have clearance issues causing the nut to not fit up against the cylinder flange as it should.
Good Luck,
Mahlon
?The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."
 
You must log in or register to reply here.