Franklin 6A4-150-B3, Service Manual

Page 1: ...SERVICE MANUAL FRANKLIN AIRCRAFT ENGINE MODELS 6A4 150 85 851 6A4 165 B5 4IRCOOLID MOTOIS II SYRACUSB HEW YORI V I A C A La ADDRES AIRCOOLED ...

Page 2: ... 6A4 150 B5 B51 6A4 165 B5 NOT LIABLE FOR ACCURACY AND EFFECTIVENESS OF ORIGINAL TEXT Air Service Caravan Co Inc INSPECTION MAINTENANCE AND OVERHAUL INSTRUCTIONS C LLEGt FI 0 JST I LTECH OLOG AIRCOOLED MOTORS INC SYRACUSE 8 NEW YORK ...

Page 3: ..._ 33 Starter Gear Assembly _ ____ ___ ___ 34 X I Cra nkshaft _____ ______ ____ _ _______________ _ ________ 15 Crankshaft Bearings___________ ____ _ ________ 16 XXII Ignition __ ________ __ _______ _____ _ ____ _ _ __ _ 35 Cra nksha ft Oil Seal __ ______ __ __ __ ________ 16 Magnetos Principles of Operation 35 1m ulse Starter on the LA 6 and XII Ca mshaft ________ _________ _____ _ _ __________ __...

Page 4: ...sued as it becomes available Please keep us advised of your current mailing address to insure prompt receipt of this material To insure that your best interests be served and satisfaction be guaranteed we recommend tha t replacements be made with genuine Franklin parts only A list of authorized Franklin distributors together with shipping instructions appears on page 7 Please address all technical...

Page 5: ... c e c en Ai ...

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Page 8: ...eto 6A4 150 B3 6 B3 1 6 4 5 3 5 335 cu in 7 1 2600 150 HP at 2600 RPM 500 to 600 Clockwise Clockwise 1 1 520 F Maximum Spark Plug 230 F 30 to 50 PSI Maximum 10 to 20 PSI Minimum 8 Quarts Free Air Temperature Viscosity Above 40 F SAE 40 Below 40 F SAE 20 25 Hours More often if condi tions warrant 040 Cylinders 1 4 5 2 3 6 28 Degrees BTC Champion J 10 014 to 018 80 Nonleaded Aviation 7 1 12 PSI Maxi...

Page 9: ...e Connecting Rod Piston Pin Piston Pin Plug Cylinder Liner Extension Below Cylinder Flange Cylinder Barrel Piston Pin End Clear Cylinder Barrel Piston Skirt Cylinder Barrel Piston Topland lands between grooves Piston Ring Gap All Rings Piston Top Piston Ring Side Clearance Piston 2nd Piston Ring Side Clearance Piston 3rd Piston Ring Side Clearance Bushing Valve Rocker Pin Mfg Min 0008T 00lT OOOST ...

Page 10: ...Gear Hub Crankshaft Ta ch Drive Driven Gears Backlash Tach Drive Connector Tach Driven Gear Ta ch Connector Sleeve Tach Drive Connector Tach Connector Sleeve Tach Drive Housing Generator Gear Hub Generator Drive Driven Gears Backlash Crankcase Dowel T iming Case Ti ming Gear Case Crankcase Dowel T iming Gea r Case Mag Adapter Timing Gear Case Sta rter Timing Gear Case Generator 001T 001T 003 003T ...

Page 11: ... 5 16 24 Starter Mounting Nut 3 8 24 145 180 Spark Plugs 14MM 180 240 Magneto Nut 7 16 20 240 300 VIII OVERHAUL PERIODS AND PERIODIC INSPE TIONS TOP OVERHAUL MAJOR OVERHAUL The time at which a top overhaul will be neces No definite period is set for a major overhaul sary will vary considerably with the type of opera Most engines will require an overhaul after 600 to tion and the care taken of the ...

Page 12: ...i Ifer Cops C h ck fo n i sk e r T ig h t ess S a fety ng G a et Condition x x x Cooling Air Baffles Check for Obstructions Leaks x x x Filters Strainers Sumps Inspect Clean x x x Compression Check Check all cylinders by pulling through Propeller x x x 7 _7 Manifold Equalizer Pipe Hose Connection Check condition of Hose and Tightness of Clamps x x x Magneto Breaker P o in ts ibut r C ck co nd it i...

Page 13: ...left case half also includes pads for the oil pump a nd oil by pass plate The cra nkcase when assembled as a unit has a top machined face to take a cover and a bottom machined face on which the oil pan is mounted On the model 6A4 150 B3 a nd B31 eng ines a n oil seal is obtai ned between the halves at the nose section by two 135 145 di ameter synthetic rubber packi ng strips These pack ing strips ...

Page 14: ...RA 1 5 When assembled with mating ha lves the crank shaft main bearing hole is bored to 2 406 to 2 407 and the camshaft bearing hole is bored to 1 1245 to 1 1250 Each of the six cylinder pods are studded at the proper locations as follows Four studs 7 16 14 NC stud end 7 16 20 NF 3 nut end driven to a height above pad of 1 1 8 Four studs 3 8 1 6 NC stud end 3 8 24 NF 3 nut end driven to a height a...

Page 15: ...he crankshaft gear starter gear and accessory drive gear The crankshaft runout token with the shaft sup ported on its main bearing journals should not exceed 002 total indicator reading The crankshaft of the 6A4 165 B3 engine is drilled at the front main journal to provide a pas sage for propeller actuating oil from the crankcase to the hollow propeller shaft The aluminum plug closing the end of t...

Page 16: ...r is pressed on to a distance of 1 034 to 1 036 from the fl ange face As the I D of the two timi ng gears is differ ent it is necessary to consult the Parts Book to determine the proper gear to order for either shaft XIII TIMING G AR CASES The case enclosing the accessory gea r train con sists of two a luminum a lloy castings the front timing or front accessory case and the rear accessory or rear ...

Page 17: ...n the throw which is nearest the flange end of the shaft The lower bushing is of the steel backed split type and the halves are interchangeable When assembling the lower cap to the rod cylinder posi tion numbers on the bosses should be on the same side of the rod The 2 4 and 6 rods have the finished rel ief surface on the top cap towards the front of the engine while the reliefs on 1 3 FIG 8 Conne...

Page 18: ...oronce 19 holes permit oil to spray upwa rd against the cyl inder walls and pistons To lubricate the piston pins and piston pin bushings three holes are drilled in the upper end of the connecti ng rod and piston pin bushing The piston pin bushing is a press fit in the 1 0375 to 1 0385 hole of the connecting rod After installation it is bored to 9847 to 9849 The bushing must be installed with the t...

Page 19: ... on the inside diameter of one face around the circum ference of the ring The ring must be installed with its undercut facing the top of the piston See Fig 11 for the diagram showing the proper ring positions 1 2 3 LJ FIG 11 Piston Ring Installation 1 Top Compression Ring 2 Middle Compression Scraper Ring 3 Oil Control Ring The middle ring is a compression scraper ring with a width of 0930 to 0935...

Page 20: ... hp model have different valve guides from the 1SO hp model and an addi tional shot peening operation has been performed on the cylinder base to provide added strength It is therefore most important that a cylinder originally mahufactured for the 1SO hp engine MUST NOT be token from stock and assembled on a 165 hp engine All cylinders for the model 6A4 1 65 B3 engine have shot peened bases During ...

Page 21: ...6 VALVE SEAT INSERT EXHAUST The exhaust valve seat insert is of stainless steel See Fig 16 2 This material has been found highly resistant to the corrosive action and high temperature of the hot exhaust gases thus reduc ing wear and warpage The exhaust valve seat insert is installed in the same manner as the inlet valve seat insert and the aluminum cylinder head material rolled over it The seat in...

Page 22: ... The cylinder is a ttached to the crankcase by using four 7 1 6 20 and four 3 8 24 hex nuts with special washers having rounded edges and safetied wi th palnuts The nuts should all be pulled down evenly to assure a good seal at the crankcase cylinder pod CYLI DER FINS Inasmuch as the cylinder cooling depends on the maximum flow of a ir over the cylinder fins it is imperative that the entire cylind...

Page 23: ...ole Turn but do not press down on the mandrel and screw the insert all the way into the spark plug hole Fig 18 3 until the end of the top thread of the insert is a half turn inside the top thread of the spark plug hole 4 Removing the Helicoil Tong 24 Break off the tang wi th a pair of long nose pliers Fig 18 4 Insert the expanding tool 18295 and torque to 120 in Ibs Fig 18 5 5 Torquing the Expande...

Page 24: ...rts On the model 6A4 150 B3 and 83 1 engines the valve spring force when compressed to the indi cated lengths is as fol lows Spring compressed to 1 5 8 46 to 52 Ibs and at 1 1 4 108 to 116 Ibs These measurements a re made wi th the spri ng da mper removed With the valve and va lve springs assembled in the cylinder the valve should support a weight of SO to 60 Ibs before t he valve sta rts to leave...

Page 25: ... Piston S Lifter Body 3 Retu rn Spring The hydraulic lifters have proven to be dependa ble through years of usage The ill ustrated views in Figure 22 shows the simplicity of construction together with the few pa rts that comprise the as sembly of the Johnson Products lifter and Figure 23 shows the Wilcox Rich lifte r 3 FIG 23 Wilcox Rich Hydraulic Valve Lifter 1 Plunger Assembly 2 Cylinder Assembl...

Page 26: ...ter valve assembly and the leak down rate which is controlled by the clear ance between the piston and the lifter body Install the valve assembly and piston without the return spring in the lifter body Place the uni t on a bench and tap the piston head sharply wi th the forefinger If the unit is in good condition the piston will rebound sharply due to the cushion effect of the air in the lifter bo...

Page 27: ...for the sa me reason The rockers See Fig 25 2 3 may be identi fied by the part number which is stamped on each piece Some rockers have only the last number of he pa rt number sta mped on the piece thus the Inlet rocker is stamped with a 7 and the exhaust rocker is stamped with an 1 8 mgs dependi ng on engine seria l number All of the forged type rockers both intake a nd exhaust have a drilled oil ...

Page 28: ...r After passing through the cooler the oi I is returned by an ex ternal line to the by pass plate It is then directed through two drilled passages running the full length of the left crankcase half The lower gallery furnishes oil to the left bonk of hydra ulic lifters The upper gallery furnishes oil to the main rod a nd ca mshaft bearings A drilled passage from the first mentioned gallery through ...

Page 29: ... 1 2 long When the oi I pump is removed from the case the location of the various screws should be noted It is essential that the screws be reassembled in the same loca tions from which they were removed The threaded hole for the cap screw on the crankcase pad where the oil pump is attached and which is nearest the second cam lobe should be checked carefully after the screws are assembled The com ...

Page 30: ...oil pressure has stabil ized the spring tension will control the valve posi tion to maintain normal pressure within specified limits The relief valve plunger and spring on early engines are located in the oil pump cover itself Inspection of the oil pressure relief valve plunger Fig 29 4 and spring can be made by removing the rear hex nut on the by pass pla te housing Inspect the plunger and bore f...

Page 31: ...her The equalizer pipes a re joined together in front of the engine by a fabric reinforced composition hose 1 1 4 inside diameter 2 1 2 long secured by two adjustable hose clamps A clamp attached under the head of a front oil pan screw and tightened with a 10 32 screw supports the weight of the front equalizer pipe assembly The hose connection on the model 6A4 165 B3 is 1 inside diameter by 2 1 2 ...

Page 32: ... impulse does not snap the magneto gear should be removed and the gear and gear spacer checked When the gear is assembled against the shoulder on the magneto drive shaft without the rubber shock absorbers in place the spacer on the shaft should protrude 001 to 007 beyond the face of the gear The permissible backlash with the drive gear is 006 to 010 GENERATOR DRIVEN GEAR The generator driven qear ...

Page 33: ...0 F to as with the crankshaft after assembly The maximum semble it on the crankshaft The end of the crank permissible runout is 016 total indicator reading 2 0020 diameter crankshaft end It is necessary starter gear should be checked for squareness XXII IGNITION To 5 Cyl To 5 Cyl Bottom Plug I To 6 Cyl Top Plug To 6 CyL I I Top Plug To 3 Cyl I I To 3 Cyl Bottom Plug 4 Cyl Top Plug f_ l To fl I rTo...

Page 34: ...r which is Incorporoted in the magneto to the spark plugs by 7 mm high tension cable containing 19 strands of tinned copper wire The ignition for the model 6A4 165 B3 and a few of the later model 6A4 150 83 engines is supplied by Bendix Scintilla S6RN 21 magnetos The Bendix and the Eisemann magnetos are similar in principle of operation and the descriptive mformation below appl ies to both Wiring ...

Page 35: ...in order to suppress contact arc ing when the pri mary current is interrupted The high tension d istributor consists of a jump gop type of rotating switch properly geared to the magnet rotor This serves to d istribute the high voltage surges to the proper cylinder at the correct t ime 26 28 High Tension Terminal Magnet Rotor Distributor Cam Breaker Assembly Pinion Gear Condenser Breaker Condenser ...

Page 36: ...tion Loosen sl ightly the two section to pull it straight back from the main hous screws which secure the brea ker assembly in the ing until dowels distributor rotor a nd coi l con end pla te and by means of the brea ker adj usti ng tactor are in the clear before attempt ing to swing eccentric Fig 37 27 set the contact for a it to the side sepa ration of from 019 to 021 See Fig 40 Wipe out any acc...

Page 37: ... to the crankshaft position by moving the points through the eccentric adjusting screw It is always good practice to check the breaker points maximum opening as outl ined in the section on minor inspection Page 37 before checking the magneto timing See Fig 40 On the model 6A4 150 B3 and 831 engines a 2 tolerance is a llowed on the igni tion timing so that 28 to 30 before top dead center is permiss...

Page 38: ...n Next turn the rotor in reverse direction to normal rotation to avoid engaging the impulse unit until the center line mark on the rotor gear is indexed with the punch mark on the breaker com gear The distributor rotor electrode is now in the 7 o clock position and is in position to fire 1 cylinder See Fig 38 Install a gasket on the magneto pod of the rear timing case and install the magneto adapt...

Page 39: ...e needle out slowly to the richest mixture that will not cause the engine to roll or run unevenly This ad justment wil l in most cases give a slightly slower idle speed than a leaner mixture adjustment with the same throttle stop screw setting but it will give the smoothest idle operation A change in the idle mixture will change the idle speed and it may be necessary to read just the idle speed wi...

Page 40: ...because of too lean a mixture STARTING COLD ENGINE At a ir tempera tures of freezing or above two or three strokes of the throttle should prime the engine sufficiently for easy starting When the engine is cranked with the starter and with the throttle cracked slightly open it should start immediately At temperatures below freezing down to about 10 F three strokes of the engine primer in addition t...

Page 41: ...r and trom the armature shaft The voltage regulator is a device that regulates the generator current and vol tage output to the battery and electrical units It protects the genera tor from overload and the battery from overcharg ing See Fig 44 It also acts as a reverse current relay to prevent battery current from flowing bock through the generator when it is not operating causing the battery to d...

Page 42: ... shaft The commutator end head supports a bearing and four brush holders and brushes The Bendix drive is an automatic clutch that engages the 4 Drive Shaft 5 Bendix Drive cranking motor with the engine flywheel when the motor cranks the engine and disengages when the engine starts It consists of a threaded sleeve fastened to the armature shaft through a drive spring and a pinion mounted on the thr...

Page 43: ...front fla nge Figure 47 shows a production type holding fixture used for engine build up Place the crankshaft with the propeller flange end down on the holding fixture base Insta ll a matched set of connecting rods on the crankshaft placing the machined surface on the rod bolt boss towards its adjacent or nearest main bea ring journal on the crankshaft Oil the cran shaft journa ls prior to install...

Page 44: ...cylinder head end of the lifter tubes Slip the tubes through the holes in the top cylinder flange with the inside wire ci rclets towa rds the crankcase Install rubber pack ings aga inst the bead on the lower end of the tube Now oil the outside diameters of the lifter tube oil seals Using a piloted driver tap the lifter tubes into position so tha t the outer end of the tubes come flush or below flu...

Page 45: ...re then torqued down evenly At the same time the two 3 8 16 x 1 hex head cap screws on either side of the case are torqued Shakeproof washers are used throughout On some engine models the pilot tennan is omitted and the two cases are al igned by means of two special hollow dowels on either side of the case Two special heat treated 1 4 28 x I through bolts machined to 2495 to 2505 diameter with fla...

Page 46: ...s of two 1 4 20 x 2 1 2 hex head cap screws as well as by the center stud at the rear end of the crankcase through the oil pan flange Torque the cap screws and use shakeproof washers Now install the rear connectmg pipes between the zone and the manifolds IMPORTANT In assembling the induction system extreme care must be exerted to see that all gaskets and packings are properly installed so as to el...

Page 47: ...fitting on t he oi l by pass pla te The pipe elbow nea r the bottom of the cooler is the oil into cooler fi tti hg a nd should be connected d irectly to the oil out of engine or rear fitting on the oil by pass plate Special formed t ubing and composit ion hoses with hose cla mps a re used for the oil cooler hook up The engine is now ready for insta lla tion on the test block or in the aircra ft de...