How are Lycoming bolt lengths measured?

[digidocs]

Let's say the parts manual calls out P/N LW-31-1.16 which is a 5/16" diameter bolt, 1.16" long. Does that mean:

A) The bolt measures 1.16" from the underside of the head to the tail (longer)
B) The bolt measures 1.16" total from the top of the head to the tail (shorter)

I think the answer is A, but I want to be sure before I do anything silly.

Thanks!
David

 

[BillL]

Some lengths are obscenely expensive.

Let's say the parts manual calls out P/N LW-31-1.16 which is a 5/16" diameter bolt, 1.16" long. Does that mean:

A) The bolt measures 1.16" from the underside of the head to the tail (longer)
B) The bolt measures 1.16" total from the top of the head to the tail (shorter)

I think the answer is A, but I want to be sure before I do anything silly.

Thanks!
David

I will add to the pretty sure category for A.

I looked up all of the available lengths when doing FWF and just ordered the cheapest sizes from Spruce. The commonly available sizes (like 1/4" increments) are the least. Honestly, if it was too long I just cut the end off, added a washer, or just left it (depending).

Kinda shade tree, but I believe that a grade 8 hardware bolt in an oil sump location provides no structural compromises what so ever. Make up your own mind about that.

 

[6 Gun]

Bolts

Lowes grade 8 bolts for case and mounting accessories not for anything that rotates .
Bob