Bolt Pattern?

[walter]

How do you determine SAE bolt pattern?

[xbirdone]

Is this a trick question?
-1 is the smaller one, -2 is the norm these days. early early Lycs were dash-1 as was 65, 85, 90, and  O-200 Continentals

[walter]

Okay maybe I need to be more specific! By looking at a crankshaft how does one determine which SAE bolt pattern it is?

[spy]

  just by looking at the crankshaft?  you cant?...the sae1 and sae2 are almost ,, almost identical.....your gonna have to consult the engine manufacturer.

[Gilbert DRIEUX]

Sure, you can determine the SAE bolt pattern by just "looking" at crankshaft.
Just to misure Bolt Circle diameter (and lug diameter):

SAE 1 is 4-3/8" (lug 5/8")  => external diameter (out of lug's holes) = 4-3/8" + 5/8" = 5".
SAE 2 is 4-3/4" (lug 5/8")  => external diameter (out of lug's holes) = 4-3/4" + 5/8" = 5-3/8".

==> SAE2 is 3/8" larger than SAE 1, with same lugs.
Cont. engines are SAE 1,
Lyc.   engines are SAE 2,  BUT O-235 can be SAE 1 or SAE 2.
My own O-235 has both patterns available on its flangue.

Regards.
PS : Have a look at Aircraft Spruce catalogue for more details.

[walter]

Thanks Gilbert! I knew the difference was a matter of measurements. Just not sure what the measurements were!

[Waiter]

ALSO - be aware that the SAE2 flange can also have different size bolt lugs;

7/16 or 1/2 (AN7 or AN8)  

Waiter

[Gilbert DRIEUX]

Exact,
 :oops: I didn't want to enter too much data upon big engines.

Lyc O-235 SAE 1 or 2    lud dia 5/8".
O-290 SAE 2  Lug dia 5/8".
O-320 SAE 2  Lug dia 5/8" or 3/4".
O-360 SAE 2  Lug dia 3/4".

From Spruce catalogue. Cann't check myself.

Jet ?  :roll:  :shock: ?? don't know            .:lol: