Home    Stinson    Aeronca                                                                                                                  ... by John Baker

Parts for the 150 and 165 HP aircraft engines in our Stinsons are becoming hard to find.   For those in need of a crankshaft, one solution that falls short of a complete engine conversion is the installation of the crankshaft from the 220 HP PZL-Franklin in the 165 HP engine.  Unfortunately, now that PZL has discontinued production of Franklin engines, availability of the 220 crank will be limited. But it is an option for those with access to whatever stock remains.

The 220 crank has a different bolt pattern on the prop flange (with a 4" bolt circle instead of the original 5.25") so it requires a different prop.  Bruce Junes of the International Stinson Club has installed the PZL crank in his airplane and provided the following information that appeared in the April 1999 issue of the SWSC "Skywriter", courtesy of SWSC president Dennis Dow:

The crankshaft substitution is covered in Franklin Service Letters 72-1, 72-2, and 72-3. When the new crank is installed, the 6A4-165-B3 becomes the 6A4-165-B4 and can be operated with either a McCauley 1A170 SFC propeller or a Sensenich M74DC.   The 6A4-150-B2 becomes the 6A4-150-B4.  The only STC involved may be the one Univair holds on the new backing plate and bulkhead required to adapt the spinner.  This information is confirmed by FAA Designated Engineering Representative Carl Gerker.  Details on this crankshaft substitution are sprinkled throughout several of Gary Murdock's articles in the "SWSC Technical Corner" compiled by Rich Fischer.  See page 113.

Further information on Sensenich propellers for the 220 Crank in the F-165 is available on the Sensenich web site at:

http://www.sensenich.com/misc/frank165.htm

Bruce Junes owns a 1946 108 Voyager, N97713, based in Eagle River, Alaska.  He has installed an F-165 from a wrecked 108-2 in his "straight" 108.   He provided the following additional information by e-mail:

As documented in Gary Murdoch's Technical Corner letters the prop will extend 1 inch further forward and require 1/2 inch AN-8 bolts with AN locknuts.  The spinner parts from Univair will come undrilled and need work before installation.

For short field work, Bruce suggests installing 8:50 or larger tires (wheel pants will no longer fit) and installing a McCauley propeller, model  1A175SFC80/43 or 1A175SFC80/44 with a 337 form.   Bruce can provide a copy of the 337 for those planning this change. This prop is a seaplane prop from a Cessna 170 on floats with an O-300D Continental engine.  New price is approximately $3000, used price about $1700.  Used ones can be found in Canada.