Franklin Engine 6A4-150-B3, B31
and 6A4-165-B3 Service Bulletins
Service News, Service Letters, Service
Information and Overhaul Information
by Larry Westin

The Franklin Service Bulletin page was first created July 28, 2009, Last updated 12/09/22.

This page has the Franklin engine Service Bulletins, Service Letter and Service News in Adobe Acrobat PDF format. Each of these scans for Service Bulletins 27 to 69 are from the original Franklin Service Bulletins which were published by Frankli. They were written and published by the Franklin Service Department between February 8, 1946 for Service Bulletin 27, through August 17, 1948 for Service Bulletin number 69. That is followed by Franklin Service News between January 16, 1950, Service News 6, through June 5, 1952, Service News 19, and Service Letter 70-1 Revision A dated March 1971.

IMPORTANT I don't have ALL the Service Bulletins, Service News or Service Letters. Service Bulletins 28, 29, and 33 have one or more pages mimeographed - which makes scanning a challenge. What I present here are copies of the information which I do have.

Most of this information was written when the engine was new. However several times recently I've received information about Stinson 108's which have been found in a barn or field, not flown for more than 50 years. There is a chance some of these Service Bulletins, Service News or Service Letters have not been incorporated in all Franklin engines as used in the Stinson 108.

One of the Service Bulletins directly relate to an Airthworthiness Directive still current today. The Service Bulletin which applies to an Airthworthiness Directive are marked with red letters saying Airthworthiness Directive.

Each Service Bulletin is it's own PDF file. You need Adobe Acrobat Reader to view.

If you don't have Adobe Acrobat Reader click here to get the free Adobe Acrobat Reader. This is a big file, about 40 Meg in size, you really should have a high speed connection to download it.


Franklin Engine Models 6A4-150-B3,
6A4-150-B31 and 6A4-165-B3 Service Bulletins

Franklin Service Bulletin Index - List of current Franklin Service Bulletins currently active, dated 5/1/56. My thanks to Charles Sullivan for this Franklin Service Bulletin Index. About 310K. Added 02/06/10.

Franklin Service Bulletin 27 - Advance Information Coverging Engines 6A4-150-B31 and 6A4-150-B3 used in Stinson 150 Voyager, dated February 8, 1946. About 345K. Added 07/28/09.

Franklin Service Bulletin 28 - Generator Gear Absorbers and Hub for Stinson Voyager 150 aircarft, dated April 8, 1946. About 165K. Added 07/28/09.

Franklin Service Bulletins 29 and 30 - No information

Franklin Service Bulletin 31 - Oil Cooler Reinforcements for 6A4-150-B3 engines, dated May 21, 1946. About 280K. Added 07/28/09.

Franklin Service Bulletin 32 - Effect of Primer On Engine Operation on Model 6A4-150-B3 engine as used in Stinson 150 Voyager, dated May 24, 1946. About 122K. Added 07/28/09.

Franklin Service Bulletin 33 - Diagram of Installation of High Tension Ignition Wires as used on model 6A4-150-B3 Franklin engines, dated June 4, 1946. About 174K. Added 07/28/09.

Franklin Service Bulletin 34 - 25 Hour Check on Oil Cooler Reinforcement Tension Band Nuts -- Model 6A4-150-B3 Franklin engines, dated August 15, 1946. About 95K. Added 07/28/09.

Franklin Service Bulletins 35 through 37 - No information

Franklin Service Bulletin 38 - Oil Seepage at Valve Rocker Covers and Lifter Rod Tube Packings on 6A4-150-B3 Franklin engines, dated October 14, 1946. NOTE see also Service Bulletin 43 below. About 128K. Added 07/28/09.

Franklin Service Bulletins 39 through 42 - No information

Franklin Service Bulletin 43 - Oil Seepage at Lifter Rod Tube Packings on 6A4-150-B3 Franklin engines, dated November 21, 1946. About 91K. Added 07/28/09.

Franklin Service Bulletin 44 - Loose inlet plugs in inlet manifold on 6A8-215-B8F & -B9F Franklin engines, dated September 21, 1953. My thanks to John Guilmette for this Franklin Service Bulletin. About 258K. Added 12/09/22.

Franklin Service Bulletin 45 - No information

Franklin Service Bulletin 46 - Suggestions for Cold Weather Operation on Franklin Engine Model 6A4-150-B3 and 6A4-150-B31, dated January 14, 1947. About 238K. Added 07/28/09.

Franklin Service Bulletin 47 - No information

Franklin Service Bulletin 48 - Fuel Pump Installation on 6A4-150-B3 and B31 engines as used on Bellanca Cruisair, dated February 8, 1947. About 217K. Added 07/28/09.

Franklin Service Bulletins 49 through 53 - No information

Franklin Service Bulletin 54 - Bendix-Scintilla Magnetos model S6LN-21 as used on Franklin Engine models 6A4-150-B3 and 6A4-165-B3 engines in Stinson Voyagers, dated May 27, 1947. About 167K. Added 07/28/09.

Franklin Service Bulletins 55 through 60 - No information

Franklin Service Bulletin 61 - Accelerator Pump Kit, Part A666-581, for engines with the Marvel-Schebler MA-3-SPA Carburetor, dated October 27, 1947. About 127K. Added 07/28/09.

Franklin Service Bulletin 62 - Drilling Moisture Drain Holes in Scintilla-Magneto Breaker Covers, dated 10/27/47, revised 6/1/55. My thanks to Charles Sullivan for this Franklin Service Bulletin. About 103K. Added 02/06/10.

Franklin Service Bulletin 63 - Fuel and Lubricating Oil as Used in Franklin Engines, dated December 10, 1947. About 86K. Added 07/28/09.

Franklin Service Bulletin 64 - No information

Franklin Service Bulletin 65 Revised - Magneto Shock Absorber Drives on Franklin Engine model 6A4-150-B3, 6A4-150-B31 and 6A4-165-B3, dated March 2, 1948. About 142K. Added 07/28/09.

Franklin Service Bulletins 65 through 68 - No information

Franklin Service Bulletin 69 - Cylinders Used on Model 6A4-150B3 and B32 Engines inthe Early 11,000 Serial Number Series on Stinson and Bellanca Installations, dated August 17, 1948. About 247K. Added 07/28/09.

Franklin Service Bulletin 70 - Ground Spring and Ground Wire Assembly as Used on Bendix-Scintilla Magnetos on Franklin Engines, dated 12/10/48, revised 6/1/55. My thanks to Charles Sullivan for this Franklin Service Bulletin. About 217K. Added 02/06/10.

Franklin Service Bulletins 71 through 78 - No information

Franklin Service Bulletin 79 - Carburetor Distributor Zones as Used on the Model 6A4-150 and 6A4-165 Engines, dated 2/23/50, revised 6/1/55. My thanks to Charles Sullivan for this Franklin Service Bulletin. About 163K. Added 02/06/10.

Franklin Service Bulletins 80 through 90 - No information

Franklin Service Bulletin 91 - Magnaflux Acceptance Standard for Connecting Rods for the 6A4-150, 6A4-165, 6V4-178 and 6V4-200 Engines, dated 3/10/53, revised 6/1/55. My thanks to Charles Sullivan for this Franklin Service Bulletin. About 291K. Added 02/06/10.

Franklin Service Bulletins 92 through 95 - No information

Franklin Service Bulletin 96 - Connecting Rod Bolt and Nut Torque Limit, dated 9/15/53, revised May 20, 1960. My thanks to Charles Wirt for this updated Revision B Franklin Service Bulletin. About 295K. Added 02/06/10, updated 02/21/10.

Franklin Service Bulletin 97 - No information

Franklin Service Bulletin 98 - Cylinder Assembly-Inspection of Hold-Down Washer Spot Face Area, dated 10/27/53, revised 6/1/55. My thanks to Charles Sullivan for this Franklin Service Bulletin. About 268K. Added 02/06/10.

Franklin Service Bulletin 99 - Connecting Rod Modification, dated 1/10/56. My thanks to Charles Sullivan for this Franklin Service Bulletin. About 268K. Added 02/06/10.

Franklin Service Bulletins 100 through 102 - No information

Franklin Service Bulletin 103 - Material for oil pump gears. Old gears 19373 and 19377, and for new type gears 19886 and 19887, dated Nov 1, 1961. My thanks to K. Alan Uhler, Jr. for this Franklin Service Bulletin. About 96K. Added 06/01/12.

Franklin Service Bulletin 104 - No information

Franklin Service Bulletin 105 - Removal of a specific lot of PiN 19751 Connecting Rods from use, dated May 15, 1963. My thanks to Charles Wirt for this Franklin Service Bulletin. About 112K. Added 08/16/09.

Franklin Service Bulletin 106 - No information

Franklin Service Bulletin 107 - Inspection of Carburetor Zone for Cracks, specifically for the 6A4-165 engine, dated December 1, 1964. My thanks to Charles Wirt for this Franklin Service Bulletin. About 151K. Added 08/16/09.

Franklin Engine Models 6A4-150-B3,
6A4-150-B31 and 6A4-165-B3 Service News

Franklin Service News Index - List of current Franklin Service News documents currently active, dated 5/1/56. My thanks to Charles Sullivan for this Franklin Service News Index. About 408K. Added 02/06/10.

Franklin Service News 1 and 2 - No information
6A3-150

Franklin Service News 3 - Crankshaft and Camshaft Gear Timing Marks, dated June 24, 1949, revised April 15, 1957. My thanks to Charles Wirt for this Franklin Service News. About 277K. Added 08/16/09.

Franklin Service News 4 - Franklin Aircraft Cylinder Reconditioning on 6A4-150, 6A4-165, 6V4-178 & 6A8-215 engines. dated November 1, 1949. My thanks to John Guilmette for this Franklin Service News. About 134K. Added 12/09/22.

Franklin Service News 5 - No information

Franklin Service News 6 - Factory Major Overhaul and Franklin Engine Overhaul-Exchange Program, dated January 16, 1950, revised June 2, 1952. About 567K. Added 07/28/09.

Franklin Service News 7 through 9 - No information

Franklin Service News 10 - Crankcase for Model 6A4-165-B3 Franklin Engine. AIRTHWORTHINESS DIRECTIVE - this Service Bulletin has compliance details for Airowrthiness Directive 51-15-02, dated December 21, 1950, revised June 3, 1952. About 302K. Added 07/28/09.

Franklin Service News 11 through 13 - No information

Franklin Service News 14 - Exahust valves used in 6A4-150, 6A4-165, 6V4-178, 6V4-200, and 6A8-215, dated 3/8/51. My thanks to Charles Sullivan for this Franklin Service News. About 111K. Added 02/06/10.

Franklin Service News 15 through 18 - No information

Franklin Service News 19 - Modification Of Franklin Model 6A4-150-B3 Engines to Provide for use of an Oil Control propeller, dated June 5, 1952. About 224K. Added 07/28/09.

Franklin Service News 20 - No information

Franklin Service News 21 - Use of Shell T.C.P. Concentrate in 6A4-150, 6A4-165, 6V4-178, 6A4-200, 6V4-200, and 6A8-215 Series Engines, dated 10/8/52, revised 1/25/54. My thanks to Charles Sullivan for this Franklin Service News. About 384K. Added 02/06/10.

Franklin Service News 22 through 34 - No information

Franklin Service News 35 - Regrinding of Nitrided Crankshafts, dated 10/27/53, revised 12/16/55. My thanks to Charles Sullivan for this Franklin Service News. About 148K. Added 02/06/10.

Franklin Service News 36 - Recommended Special Tools for Franklin Model 6A4-150-B3, 6A4-165-B3, 6V4-178-B32 and B33, 6V4-200-C32 and C33 Engines, dated 12/17/53, revised 2/8/56. My thanks to Charles Sullivan for this Franklin Service News. About 377K. Added 02/06/10.

Franklin Service News 37 through 38 - No information

Franklin Service News 39 - Engine Overspeeding, dated 2/2/54. My thanks to Charles Sullivan for this Franklin Service News. About 133K. Added 02/06/10.

Franklin Service News 40 through 41 - No information

Franklin Service News 42 - Inspection of Throttle Body to Bowl Gaskets on Marvel Schebler MA-4-5 Carburetors on Models 6A4-165, 6V4-178, 6V4-200 and 6A8-215 Engines, dated 3/24/54, revised 3/1/55. My thanks to Charles Sullivan for this Franklin Service News. About 142K. Added 02/06/10.

Franklin Service News 43 - No information

Franklin Service News 44 - Oil Cooler Thermostat for Franklin Models 6A4-150 and 6A4-165 Engines, dated 12/21/54. My thanks to Charles Sullivan for this Franklin Service News. About 115K. Added 02/06/10.

Franklin Service News 45 - No information

Franklin Service News 46 - Valve Lifters for Model 6A4-165-B3, 6V4-178-B32 and C33, 6V4-200-C32 and C33 Engines, dated 12/29/54, revised 4/12/55. My thanks to Charles Sullivan for this Franklin Service News. About 153K. Added 02/06/10.

Franklin Service News 47 - No information

Franklin Service News 48 - Electric Tachometer Drive Kit for Model 6V4-178 and 6V4-200 Engines, dated 11/25/55. My thanks to Cy Galley for this Franklin Service News. About 62K. Added 08/31/12.

Franklin Service News 49 - Identification of Model 6V4-200C32 and 6V4-200C33 Engine Configurations, dated 12/13/55. My thanks to Cy Galley for this Franklin Service News. About 57K. Added 08/31/12.

Franklin Service News 50 - Approved Spark Plugs for Franklin Aircraft Engines, dated 12/14/55, revised 3/19/56. My thanks to Charles Sullivan for this Franklin Service News. About 138K. Added 02/06/10.

Franklin Service News 51 - No information

Franklin Service News 52 - Approved Changes and Modifications, dated February 15, 1959, revised March 5, 1959. My thanks to Charles Wirt for this Franklin Service News. About 313K. Added 08/16/09.

Franklin Engine Models 6A4-150-B3,
6A4-150-B31 and 6A4-165-B3 Service Letters

Franklin Service Letter 70-1a Revision A - Recommended Time Between Overhauls (TBO), dated March 1971. My thanks to Rich Preiser for sending me a copy of this service letter. About 160K. Added 07/28/09.

Franklin Engine Models 6A4-150-B3,
6A4-150-B31 and 6A4-165-B3 Service Information
and Overhaul Changes

Franklin Service Information I-1 through I-2 - No information

Franklin Service Information 3 - Replacement of Cylinder Liners on Models 6A4-150, 6A4-165, 6V4-178 and 6V4-200 Engines, dated 08/21/51, updated 07/01/55. My thanks to Cy Galley for this Franklin Service News. About 28K. Added 08/31/12.

Franklin Service Information I-4 through I-7 - No information

Franklin Service Information 8 - Connecting Rod Assy 0 - Instructions for Replacement of, dated May 25, 1950. My thanks to Charles Wirt for this Franklin Service Bulletin. About 255K. Added 08/16/09.

Franklin Overhaul Change 8 - More information about Connecting Rods. My thanks to Charles Wirt for this Franklin Service Bulletin. About 227K. Added 08/16/09.

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