This is from Stoddard Areo Service , Dated 14 June 1973.
Camera does not work so here it goes.
Instructions for the following 0-320 series engines in a Piper PA-12, PA-14 Airplane (0-320-A1A,A1b,A2a,A2BA2c,A3A,A3B,A3C, C2A,C2B,C3A,C3B)
(Includes Basic 0-329) USE M74DM Sensenich Propeller, Minimum51 Pitch
1.Remove engine, mount etc. from firewall forward, saving only muffler, (If PA-20 or PA-22 exhaust system is to be used) Cowling., carburetor air box and in case of the PA-14, the muffler heat muff, if in good condition.
2. Install Stoddard Areo Service Engine Mont, Model 501, using the original bolts or new bolts of the original length.
3 Install 0-320 engine using 4 AN8-44 Bolts. Engine will be baffled and have oil radiator as installed on Piper PA-18-150 as follows, Lycoming P/N 72150 inter-cylinder. (2) 71610 hook, (2) 71611 bracket, (1 each) 14439-00, 14440-00, 14455-00, 14456-00, 14452-00, 14467-00 and (2) 14513 tie-rods, oil radiator is a Harrison ( Piper P/N 455168.)
4. Install PA-18, PA-20 or PA-22 cross over exhaust system.
5. Modify carburetor air box by carefully cutting opening in top left rear of the box to accommodate the lower part of the carburetor accelerator pump. Make opening fit closely to prevent entrance of large amounts of unfiltered air. Install air box. Cut carburetor heat and mixture control wire to proper length and connect. Adjust and connect throttle control, connect generator wires, oil pressure line, oil temperature bulb and magneto ground wires. PA-18 air box and filter may be used as optional installation.
6.Modify the nose cowl by adding oil radiator adaptor ( P/N 13717-00). Clamp nose-cowl to starter gear support using 1/2" spacer blocks for clearance. Cut equal amounts from each end of the channel braces that support nose- cowl. Cut top of cowl to fit ( if baffle felt does not fit tightly against top cowl, replace felt with wider strip), Cut approximately 1.5" from the front of the side cowls and trim to fit.
Rear of side cowling will not need to be cut. Remove air scoop from lower cowl and move air box opening rearward approximately 1.5" or until it properly fits the air box.
Slit the bottom cowl down the center from the front of the cowling to the air box opening and overlap to remove excess fullness. Rivet neatly with a row of aluminum rivets spaced about 1" apart. Reinstall air scoop. Provide opening in top cowl for oil filter.
7. Connect primer and fuel lines, fill with proper grade oil and test run. Engine mount is (3") shorter than standard mount so be shure to use new arm when figuring weight and balance. refer to engine spec. for weight difference. Complete FAA Form 337 stating that installation was made in accordance with STC SA 83 Al.
8. Approved in land plane, sea plane and ski plane configuration.
Normal category only.
Amended Date 14 June 1973
This is what I have pertaining to the O-320 Instructions for my aircraft that was modified back I the 70;s or 80's.
This was written as Stoddard sent .
Hope this helps someone out.