Nuts!

[Rick RV-4]

Allright, another dumb question . . . what kind of hardware is everyone using to secure items onto the studs that are attached to the under side and back of a Lycoming engine?

More specifically, I need to know what type of nuts and washers are used to:

(1) Secure the carburetor to the bottom four studs on the bottom of the sump, and

(2) The nuts/washers used to secure the mags to the studs on the back of the accessory case.

(3) Secure the starter to the three studs on the fron bottom . . .

I believe all of these studs are 5/16"-18 (coarse thread?), but I couldn't find any nuts that match this description at the normal parts stores (Aircraft Spruce, Wicks, etc).

Losing hair by the minute . . .

 

[az_gila]

Aircraft Spruce - Lycoming

Lycoming calls then STD-1410 "NUT, 5/16 - 18 plain".

I think they are thicker than standard.... and are also Lycoming exhaust mounting nuts.

Aircraft Spruce hid them on this page.... $1.64 each...

http://www.aircraftspruce.com/pdf/2007Individual/Cat07301.pdf

The lock washers are STD-475 ... a web search of Aircraft Spruce finds them at 4 cents each...

The flat washers can be found the same way "STD-35" at an exorbitant $1.36 each...

gil in Tucson

 

[GAHco]

Nuts

The STD 1410 is the called out item in the parts manual.

A lot of engine builders purchase the MS51967-5, I suspect for similar purposes.

http://www.gen-aircraft-hardware.co...uts -> Nuts&menuID=122~123~123~124~124&id=126

Select the prefix ms51967
Select the suffix -5

See "Detailed Image"

This might help.

 

[Flying Scotsman]

Lycoming calls then STD-1410 "NUT, 5/16 - 18 plain".

I think they are thicker than standard.... and are also Lycoming exhaust mounting nuts.

Aircraft Spruce hid them on this page.... $1.64 each...

http://www.aircraftspruce.com/pdf/2007Individual/Cat07301.pdf

The lock washers are STD-475 ... a web search of Aircraft Spruce finds them at 4 cents each...

The flat washers can be found the same way "STD-35" at an exorbitant $1.36 each...

gil in Tucson

OK, somebody tell me...is there some magic difference between STD35 washers and regular AN washers? $1.36 each seems, um, a tad high...

Similarly for the other parts...what's special about the nuts? and the lock washers?

 

[Flying Scotsman]

OK, somebody tell me...is there some magic difference between STD35 washers and regular AN washers? $1.36 each seems, um, a tad high...

Similarly for the other parts...what's special about the nuts? and the lock washers?

No help?

If there's *really* a difference, I'll pony up the cash...but I'm a little loathe to pay a buck and a half for an AN960 washer, etc.

 

[N999BT]

Magneto Clamp Washer

The washer for the mag clamp is called out in the O-360-A parts manual as a STD-1727, Washer, Plain, 3/4" OD x 21/64 ID x 1/8 thick. It is NOT standard (except from Lycoming). You might want to call Lycon or somebody like that to order a package of nuts and washers. Compared to the price of other stuff you have to buy getting the right hardware is not that bad.

 

[Flying Scotsman]

The washer for the mag clamp is called out in the O-360-A parts manual as a STD-1727, Washer, Plain, 3/4" OD x 21/64 ID x 1/8 thick. It is NOT standard (except from Lycoming). You might want to call Lycon or somebody like that to order a package of nuts and washers. Compared to the price of other stuff you have to buy getting the right hardware is not that bad.

I'm not there yet, but I'll check on that one...

As far as I can tell, the nuts for the exhaust flange, for example, are simply Grade B nuts of the appropriate thread. The washers sure look like AN washers. If that is true, then they are grotesquely overpriced. I'm really not anxious to get ripped off, even for a modest amount. At a total of $3 for each nut/washer/lockwasher combination, that's $24 for the complete exhaust set, vs maybe a third of that at most.

 

[WenEng]

You are paying for ''certified'' hardware....

Gotta keep money in the till to pay claimswhen you sue for that defective washer.....

 

[osxuser]

I've seen certified lycs use all kinds of stuff. Even just off the shelf grade 5 stuff. (Grade 8 is tooooo brittle).

Use that little bit of info at your own risk. I go for the book hardware myself.

 

[rdamazio]

The lock washers are STD-475 ... a web search of Aircraft Spruce finds them at 4 cents each...

I found this thread while looking for possible alternatives for this washer, 'cause they're now...$1.95 each! Not a huge deal in absolute terms, but staggering to see the increase. (I also just paid $34 for ONE Lyc bolt to attach my starter...)

 

[wirejock]

Grade 5

I've seen certified lycs use all kinds of stuff. Even just off the shelf grade 5 stuff. (Grade 8 is tooooo brittle).

Use that little bit of info at your own risk. I go for the book hardware myself.

What he ^ said.
Grade 5 hardware.

 

[JDeanda]

Brass

Maybe a bit of an outrage here but Continental sells tall brass exhaust nuts that work great on Lycomings. https://www.aircraftspruce.com/catalog/hapages/manifoldnuts.php?clickkey=13943 They’re pretty spendy but they don’t rust themselves into place and can be removed easily when the time comes. (So much fun when you need to remove a pipe to change a gasket and the stud comes out of the head along with the nut.) I’ve used brass hardware store nuts and they’re fine. McMaster-Carr is a good supplier, too. I’ve also been known to drill out and tap one size smaller nuts to add a bit of clearance between the nuts and the exhaust pipe. BTW, a 1/4” drive universal socket (not a standard socket in a universal) on a long extension saves a lot of wiggling and looking for access angles.