Firestone 1952  5 hp, Getting it Running Again

   One thing that I want to convey here is that I write only on motors that I have actually worked on, and over a period of MANY years, consisting of many THOUSANDS of hours, and then more in maintaining/updating these pages.  These articles are usually motor specific, HOWEVER if you are having a diagnosis issue, my Trouble Shooting article covers MANY more aspects that may help you diagnose your issue.  CLICK HERE for access to that article.

     What Do We Have Here? ;   The motor we will be discussing here was a non running (like possibly for 25 years OR MORE) was a 1952  5 hp Firestone motor that was donated to me by my Son-In-Law that was given to him by a cousin as a result of it not being sold at a garage sale.  This motor was made by Scott-Atwater as describe below.

  C.E. Scott and H.B. Atwater owned a small tool making and punch press operation.  They had started the business in 1932. In 1935 a gentlemen named DuMonte approached them to build a small outboard for him to sell.  The motor was put on display at a New York exhibit.  Report has it that several hundred of the outboards were ordered.  Before the motors were turned over to DuMonte they installed some decals of the name CHAMPION. They were still doing their tool and punch press operation as well as building outboards.

  In 1939 DuMonte landed a contract with Firestone to sell the CHAMPIONS in their tire stores.  This forced both C.E Scott and H.B. Atwater to start building outboards full time.  In 1941 Scott and Atwater with their CHAMPION outboards were the second largest outboard manufacturer in America.  At that time only Evinrude was larger.  This relationship with DuMonte and the CHAMPION outboards went from 1935 until 1942.  World War 2 had forced most machine shops to doing military work and Scott and Atwater were no exception.  After the war, DuMonte decided to build his own motors. Firestone still wanting outboards stayed with Scott and Atwater to supply their motors.

  In 1946 FIRESTONE and SCOTT-ATWATER outboards hit the market.  They offered a 3.6 hp in 1946, adding the 7 1/2hp in 1947.  By 1949 their line had grown to a 3.6, 4, 5, and 7 1/2 hp.  The 4 thru 7 1/2 outboards were available with full shift F-N-R.  Making them the first outboard company with a line of full shift motors.  

 

   1950 offered in addition a 16 hp shift motor. 

 

   In 1951 they added a 10 hp along with being the first manufacturer to utilize the single line fuel system.  This brought their line in 1951 to a 3.6, 4, 5, 7 1/2, 10 and a 16 hp.  This same year brought the speed designations on the line of outboards.

 

  The numbers that have been seen on the cowlings were for a speed rating, like. 1-12 would be a 3.6 hp. It would push a boat from 1 to 12 mph.  This speed designation was only used in 1951 and 1952.  You can check the Scott-Atwater Year Locator to see all the models and years as well as the speed designations.

  In 1952 the 4 hp was dropped from the line. 

  1953 brought on the Golden Pennant.  A dark green bottom and a gold top.  This was only used on the 7 1/2 and the 10 hp.  This new color scheme with the addition of the two outboards being a thin motor with a band and a cowling that split down the middle didn't sell as well and was only run that one year.

 

  In 1953 the cowling design was changed and the remote single line fuel system was introduced.

  In 1954 the invention of the Bail-A-Matic was introduced on the 5, 7 1/2, 10 and 16 hp motors.  This feature would allow you to drop a small unit in the bottom of a boat and a hose would lead to the outboard where it would bail out water.  In these early years most boats were wood and as we all know had the tendency to leak a little water.  This feature didn't win the population over.  It had its share of problems (being they relocated the water pump and a second pump for the Bail-A-Matic up under the powerhead which caused cooling problems when things got worn).  The Bail-A-Matic was no longer advertised as a top feature.  But the water pumps still stayed in the upper non-ideal locvation.

  In 1955 they introduced their 30 hp outboard.  In 1956 it was changed to a 33 hp.  Their line for 1956 was a 3.6, 5, 7 1/2, 10, 16 manual start, 16 electric start and a 33 hp.  This same year Scott-Atwater was approached by McCulloch to buy the outboard operation.  Scott-Atwater did sell out this same year.  1956 also saw the last year of the Corsair outboard.  An outboard that Scott-Atwater had produced since 1946.  (I will list the other outboards Scott-Atwater produced at the bottom of this page.)

  In 1957 the 33 hp became a 40 hp.  Although the name Scott-Atwater was still on the cowling they called themselves Scott.  Also in 1957 the fiberglass cowling appeared on some of the outboards.  1958 saw the beginning of their new 60 hp that was a 3 cylinder.  The name on the outboards eventually became Scott and Scott-McCulloch.  By 1964 all of the motors were changed to McCulloch.  Because I am a Scott-Atwater fan while Cliff Scott and Bruce Atwater owned them, I only follow the years from 1935 to 1957.  All I really know about McCulloch is that sometime in the mid to late 60's they stopped producing the outboards.  I hope this has allowed you to learn more about these outboards and the two early pioneers in the outboard industry.

  This list is of the outboards that Scott-Atwater produced.  Some of these models were picked up by other companies as with the case with Firestone.

Champion outboards    1935-1942

Scott-Atwater                1946-1959

Firestone Outboards     1946-1957  (may have been into 1958)

Corsair Outboards        1948-1957

Hiawatha                       1956-1959  (may have been into 1960)

Wizard                           1959-?     This was only added because in 1959 and or 1960 the Bail-A-Matic feature was on some of these outboards that McCulloch produced for Western Auto.

 

This page above was copied from http://www.scottatwater.com

 

 

   Statistics For These Motors :

 Specifications on this Firestone motor are -- Stock number 10-A-73  Code number 133-2-1725  Serial number1725-4861 which the 25 equals to Scott-Atwater's year of production and hp code AFTER 1951 being, being  (3725 but 1725 for Firestone) which represents 1952.   The 3 (or1) meaning Scott-Atwater, 7 equating to the 5 hp and the 25 is the year written backwards.  

 

These are Water Cooled, twin cylinder, 2 cycle motors which the develop 5hp  @ 4200 RPM
Bore diameter       1.6875" 
Stroke                    1.6719"
Displacement         7.48  CI
Starter                   manual recoil rope type
Bearings,               Ball & Needle roller bearings throughout

Carburetor -          Tillotson MD

High speed jet -     Adjustable
Idle jet     -             Starting point 1 turn out
Fuel capacity  -     Integral 1 gallon fuel tank
Fuel Shut off -       Valve attached directly to front bottom of carb
Fuel mix  -             Per gallon of gas, SAE-30  Oil 1/3 pt.   50-1 Ratio

Wico Magneto -     Point gap of .020"
Spark plug  -          Champion H10 gap .030"
Flywheel key -       ??
Flywheel nut  -     7/16" X 20 NF, -- 5/8" wrench size
Shaft length -        Short -15"
Water Pump -        Rubber impeller

Gearbox  -             Forward/Neutral/Reverse

Gearbox oil -         Hypoid 80 /90

Shear Pin -            None -  Slip clutch
Gear Ratio -           ??

Prop -                    7 1/2" X 6 1/4"  2 blade RH 
Prop nut  -            1/2" X 16 NC  -- conical nose Brass  -- 13/16" wrench

Prop Nut cotter pin -  3/32" X 1 1/4"   stainless steel

Weight                   46#

Retail price -         When new: $169.95

  Then trying to find much info on the internet proved that not a lot was available.  However I did download a 697 page pdf factory service manual (for a cost of $5.95), which was a bargain, but even though it showed all the models of a 10 year span (1946-1956.   It was very helpful, however just trying to understand their code system and to pick out the right one was an issue (remember almost 700 pages and who knows how many models/sizes).

     Inspect It ;   This motor was intact, but many parts were very close to being seized, but the starter rope pulled the engine over, the tilt and swiveling of the clamping bracket were barely operational and it was covered with what appeared to be salt air type corrosion mixed with fine sawdust.  The paint, (a light metallic green) was not the best as it appears there was no primer coat, nor an overcoat of this paint job.  The steel gas tank was intact with no dents, but had some surface rust on the top, and with a lot of salt air type corrosion on all of the lower parts, will need to be addressed, OR just clean it up and enjoy the outcome.

    First off, I removed the starter unit, then the side covers, exposing the bare powerhead.  This one seemed to be built more reliable than other makes for the same years that I have seen.  This recoil starter appears to be built very substantial, as in many of the other brands of this era, the starter ratchet engagement dog spring systems are woefully lacking good long term engineering.  This one is also very accessible, where the complete unit being attached onto the top of the gas tank using 3 screws.  In the photo below on the left, you can see the spring loaded ratchet dogs that engage the unseen notches in the spool of the cage mounted on top of the flywheel.

 

Here we see the recoil starter system

   Disassembling It ;   In disassembling this motor, the stamped steel gas tank is bolted onto 3 anchor arms attached to the block, one at the front and 2 on each side just slightly forward of the center of the flywheel.  These (2) aluminum spacers are 3/4" OD X 9/16" long and with a 1/4" hole in the center, which go the front 2 bolts as spacers off the block.  To this, the rope recoil starter is attached using three screws.  The 2 cast aluminum side skirts are attached to the block, each with 2 more screws.  At the front sides a carrying handle is bolted onto the front of the side of both skirts.  At the RH rear this skirt is short at the rear, using a smaller separate cover that can be removed to access the spark plugs without removing the side skirts.  Again 1 more aluminum spacer is used on the LH skirt's rear screw.

  My next thing was to check compression.  The spark plugs (Champion H10) looked brand new on the inside.   Then squirt some motor oil into the spark plug holes and rotate the flywheel a few times to distribute the oil.  Now by using a rope as a starter, winding it onto the flywheel, pull it over fast about 3 times for each cylinder.   Compression was not bad, 72# on the top with 90# on the bottom.  Not being close to equal as recommended, but at this stage, I will accept that maybe it will improve after it has ran a bit.    Fast Forward --  after running this motor on the lake, the compression went up to equal the bottom, both are now 90#.  Quite respectable for this old motor.

      Electronics ;  Next, I pulled the flywheel to inspect the points, condensers and coils.  The only thing obvious was slight rust on the steel coil metal surface that comes near the flywheel for magneto operation.   The coils looked good, with no cracks in the outer covers.   While there, I ran a thin strip of 220 grit sandpaper between the points contacts to remove any oxidation.  I did not check them for settings, as they looked pretty close to .020" to my experienced eye.  I had my Son-In-Law hold the spark plugs to ground as I pulled the flywheel over rapidly using a rope.  We got spark on #2 wire, but #1 was totally dead. 

   OK, more re-checking needed under the flywheel.  My guess was that there may have been a loose or corroded wire connection.  When there, the second time, upon CLOSER inspection I did find that the spark plug wires leading from the coils were simply pushed into and pinched over in the hole of the metal contact lug of the coils.  I soldered both connections like they should have been, and replaced the flywheel.  BINGO, I now have spark to both spark plugs. 

    Now, this brings up the question, was this the condition as it came from the factory?  And if so, possibly since it could only have been running intermittently on one or both cylinders, that may have been why it appears to have just sat in a corner collecting dust and rust for all those years?

Here you see under the flywheel, which is very clean, the coils, points & condensers

 

      Carburetor ;   These Tillotson carburetors are rather simple and a very common basic model used on many small outboards in those years.   This one was relatively clean on the inside, indicating that the fuel line had been shut off and the motor had been ran until it died because of lack of fuel.   But it had a light salt air type corrosion on the outside, so an overnight soaking in carb cleaner was in order to sure it was clean.  A nice thing about this carburetor is that it has on the bottom fuel inlet fitting from the tank's line, a neat shut off valve knob accessible from the front outside (as seen on the photos below). 

   Another impressive item, was that the adjustable main-jet knob (the large black knob in the center of the LH photo below) also works as an independent choke, if you push the knob in at any rotationional position.  This is accomplished by the outer edge of the knob coming in contact with the looped wire shown in the LH photo, which in turn activates the choke arm on the left.

  As a side note, after soaking the carb and before I got it back together, I slipped, almost fell and lost the idle needle in 4" of loose snow of my sidewalk.  It being brass, a magnet would not be of any help in locating it.  After what seemed like hours of looking, I gave up (never did find it).  Now what??   BINGO, this carb was a Tillotson, and in my pile of old (resting) motors there was about a 1946  2 1/2hp Elgin in VERY BAD CONDITION (lots of parts broken or missing) that I had salvaged 40 years ago (during an elk hunting trip) from a illegal, dead end Weyerhaeuser logging road garbage dump (I don't consider myself a hoarder, but you just never know when you will use things like this).  This carb was the same make and model, but just a simpler version.  And this idle needle fit, so now it has found a new home in my Firestone carburetor.  

    In the photos below, you can see the fuel tank shut off valve.

Here is the carburetor from the front	Here is the carburetor from the RH side

     Anti-Kick Up ;   Here, the factory's design to prevent motor kick up when in reverse was solved by the shifting lever activated a sliding sleeve riding over the steering column, all of which being exposed.  As the shifting lever is moved rearward, which slides the sleeve down and over a lug on the transom pivot at the bottom of it's travel, securing the exhaust housing/lower unit to the steering column/clamping bracket.  In the photo below, the shifting slider is not shown not quite all the way down in order to show the upward protrusion that the slider can move farther down to lock it.  The actual shifting rod is attached to the lever unit and resides inside this steering column tube.

 

Here we see the simple shifting reverse interlock

 
  Trim Lock ;  This motor's trim lock (trim to the transom angle), uses a 5/16" Ell shaped pin that has a spring detent on the long end.  The mounting bracket has 4 adjustment holes as seen in the photo above.  However to make any adjustment, there is a 1/4" horizontal cross bolt (also as seen in the photo above) that needs to be loosened in order for the front pivot bearing surface to realign if using a different hole.

   Tilt Lock ;  This motor does not have a automatic tilt lock, however there are (2) horizontal 5/16" holes on the upper inner mounting bracket (again as seen in the photo above), that when the motor is tipped all the way up, by removing the trim pin and installing it in these upper holes, this will lock the motor up during traveling.  And during this traveling, there is really no need for it in the trim position.

     Pivoting Swivel ;  Here the rotational friction adjustment is governed by a single 5/16" bolt (1/2" head) that is located at the top front of the motor mount.  It is more accessible by tipping the motor up and accessing the bolt head from up underneath.

      Fuel Tank ;  The gas tank had some evidence of evaporated dried gas, along with a slight amount of rust, as this tank was made from stamped out sheet steel.  Here, my method of cleaning the internal parts of the tanks was for some time to use paint stripper and triangular abrasive tumbling stones.  HOWEVER I must have gotten a different brand this time, which was thicker, so I tried to dilute it with water.  BIG MISTAKE.  As this mixture now turned into a sticky-hardish gel coating the whole bottom and slightly up the sides before I dumped it all out.

 

Here you see the result of my screw up

    So my next move was to use Acetone, AND again the handful of triangular abrasive tumbling stones, and every time I pass by it in my shop for a number of days now, pick it up and shake it vigorously in all directions.  The Acetone helped loosen the dried crud, and the stones abate both the crud and the rust in the tank by the shaking.   It took considerably longer to get this crud loose. and by using a long screwdriver, break more loose, then with a long 4 pronged mechanics pickup tool, I remove bits and pieces of the hardened crud.  I got what appears to be about all out, and if I didn't, WELL?  This method removes enough to ensure clean fuel going into the carburetor because of a fine screen inside the tank at the outlet.

   While the tank was soaking, a thorough examination of all the rest of the moving parts was done.  Like check the steering, which was really tight.  By squirting WD-40 on/in numerous locations, which did wonders.   I found a 5/16" bolt head protruding from the front top of the pivot column.  Loosen it a couple of turns and now it moves a lot easier.

    In my examination, I noticed that this motor does not have a thermostat, meaning (in all probability) that the head gasket was engineered (having holes strategically located) to restrict/control the cooling water flow.  This design was used on a 1947, 2 1/2hp single cylinder Elgin motor that I have owned/rebuilt since about 1960.

    Here is an excerpt from the factory service manual.  WATER PUMP  Check the water discharge when the motor is running.  At high speed the water should be discharged in a steady stream.  At idling speed the discharge will be
broken up into a fine mist by the exhaust relief.  The temperature of the water discharged should not be so hot that you can not hold your hand under it.  If it is too hot, not enough water is being circulated, and the water pump and all water lines should be checked.

   Here, also in a cost saving  situation for the Firestone motors, this motor uses a separate aluminum plate as a anti-cavitation plate as compared to having it cast into the gearcase or lower exhaust housing.

   Water Pump Repair ;   Here is an excerpt from the factory service manual.  SHIFT MODEL WATER PUMP  The water pump is a positive rotary vane type impeller made of special synthetic rubber, which rotates in a stainless steel cavity.  Both the impeller and the cavity are replaceable, but this is seldom necessary.  Operation in even the most sandy water will not appreciably wear down the cavity.  When installing a new impeller, make sure that it does not bind over the pump drive pin on the driveshaft.  If the impeller binds, the edges of the pump pin should be filed slightly to allow the pump to float on the shaft.  The lower pump seal should be replaced when installing a new cavity and the cavity should be held in place with Duco cement

Since this motor is now 70 years old and has sat for a unknown number of years, the condition of the water pump impeller being unknown and replacement parts are not readily available.  AND whereas water flow is critical on all water cooled outboards, it seemed prudent to replace this impeller while I now have it apart.  There is one person who caters to these motors, but he only offers an exchange of the old impeller (reusing your old hub).  To accomplish this, I ferreted out his name and sent an e-mail, then got this simple reply the next day.  He can be reached at   'Baron0418@att.net'

,  Send me your old impeller, $27 Cash, check or Postal MO to Brian Wilcox 9231 Stone Rd. Algonac, Mi  48001. 

    I sent him $30 cash and got the new impeller within 10 days.

This obsolete water pump impeller #493-5100 uses 6 vanes, with dimensions of the pump liner being 1/2" hole, .500 thick and the liner being 1.500" ID.   While measuring the new impeller, it was .593' thick and 1.600" OD.  This impeller has key slots on both sides of the hub at 180 degrees to each other.

   In the photo below, this badly deformed impeller is probably the original to this motor.  Here the vanes have taken a set to where it would be unwise to rely on it, as the vanes now do not have enough of a diameter to even contact the widest part of the cup, very badly restricting the proper functioning.

Here we see a  very badly deformed impeller	Here we see the new replacement impeller

    OK, now disassemble the lower unit and get into the water pump.  This lower unit is different than the many others that I have dealt with in the past 50 some years of outboard motor tinkering.  These lower units have a nose cap for the gearbox that is screwed on, using 3 machine screws (2 small #10 on the sides and a 1/4" on the bottom).   This cap is the front part of the gearbox, so in removing it, you also expose all the gears AND the gear oil as well, if you have not already drained it.  It was pretty obvious that this oil was probably original, as it looked more like BLACK tar.

    Shifting ;   The shifting mechanism works vertically and is located in the front of this cap.  It has a small metal fork that slides into a round threaded 1/4" connector button on the bottom of the shifting rod.   This button, being threaded can be adjusted, but on this one, the bottom of the button was flush with the bottom end of the shifting rod, which is what the manual lists.  This button has to be removed to allow the shifting rod to slide up and out of the lower unit.  This button has 2 slots (one on each side) that mate into the fork sides horizontally, making an easy slip in connection to remove the cap.  

    I did not take dimensions when I had it apart, and I think the threads were 1/4 X 28 NF.   To make one, you could braze/silver solder 2 nuts together (on a bolt for thread alignment) then file slots in the center on each side to allow the shifting fork to slide into.  Note -- it is limited to overall height, otherwise the rod will not raise high enough to engage the gear.

Here we see the shifting connection in the gearbox nose cap visible just above the screw bosses	Here is a blown up view of connector button

 
     Gearbox ;   Now to remove the gearbox, which was by removing the (2) 5/16" nuts (1/2" wrench) off the studs mounted in the lower exhaust housing and under the cavitation plate.  This allowed the gearbox to be slid down and supposedly off, as the driveshaft is withdrawn down and out of the exhaust housing exposing the water pump.   This one did not allow the upper driveshaft to come down and out, which complicated reassembly.

   So, to access the internals for further disassembly and to get the impeller off, I had to clean this old gear oil out, because on this model the lower end of the driveshaft, being square, engaged the square hole in the drive gear and was held in place by a horizontal cotter pin through the gear and the shaft (hid in the gear oil).  This would have been about impossible to detect without referring to the service manual. 

   Disassembly, with the nosecone off -- (1) Remove the prop and pull the prop shaft and gears out toward the front.  (2) In order to get the driveshaft cotter pin out, you have to rotate the driveshaft AND drive gear enough to be able to close the ears of the spread out cotter pin, located in the upper base of the drive gear.   You can not rotate the shaft fully because there is not enough clearance behind or sides for the extra length now of the cotter pin.   So move it back AND twist off both tails of the cotter pin.  Now rotate it 180 degrees and using pliers, pull the now broken off/shortened cotter pin out by it's head. 

   If you could raise the top wear plate and the impeller on the drives shaft, with the prop shaft out, you should be able to drop the driveshaft, BUT NO, because of the impeller key/pin is too large to pass through the top stainless steel impeller plate, so it is locked in place.  So with the drive gear off the shaft, separate the parts enough to remove the impeller key.  Now the gearbox can be removed.

   Since replacement parts are virtually non existent, the gasket between the gearcase and the front nose cap had to be made out of bulk gasket material. 

    While this motor this far torn down, it may be wise to see if I can also replace the propeller shaft seal.  Partly because of it's age and then when removing the prop, there was over 12" of old cuttyhunk line imbedded into this seal.  Upon close inspection, I find a name and part number on the rear of the existing seal.   Victor 62004, which now gives me the chance to cross reference it to a more common brand used currently.  Thus another trip to my friendly local auto parts store, but no cross-reference was available.  So I measured it, the prop shaft was .500" with the OD of the seal being 1.000" and as close as I could measure while it was still pressed into the housing was about .312" thick.  This was probably common 70 years ago, but now most all bearings and seals are metric.  I did find one that had the main dimensions OK, but a tad bit thinner, which should not be an issue.

    On final assembly this motor, it is better than some others, in connecting the water outlet from the water pump to the tube leading up to the powerhead.  There is no blind guessing of fishing up inside the exhaust housing here for tube connections, as the outlet is built into the housing whereby there is no guessing when everything bolts together.  A plus here.

     Shifting ;   On many motors the clutch dogs on the slider are rectangular, fitting into a slightly larger rectangle hole in the forward/reverse gears.  This makes for a solid engagement, BUT (if the motor is not running) and you try to shift, your chances are slim that they will engage.  This also causes broken shifting handles if the owner does not read or understand the situation.   It also causes the leading edges of these dogs to (over time when shifting while running at a higher RPM) to become worn, creating a situation where they will not hold securely and the motor can jump out of gear if under load.    However on this motor, the dogs are a type of ratchet, making for smoother shifting at any position, and minimizing chance of wear.

    Reassemble It ;  You will note that there are some hardened bronze thrust washers inside the gearbox.  These has "ears" to engage corresponding notches in either the gears or housing.   These bronze thrust washers in front of the needle roller bearings have projections that must fit into slots in the housing to prevent the thrust washer's turning.   If improperly installed, damage will occur to thrust washer and bearings.  The front and rear washers are different as explained below.

    In reassembling of the gearbox,    (1)   Install the shifting rod grommet in the appropriate hole in the cavitation plate, slide this plate  onto the drive shaft (2) Slide the top wear plate onto the drive shaft, (NOTE) the word "TOP" on it.  Clean and re-install the water intake screens in the front of the housing.  (3) install the stainless steel top water pump cover (TOP) side up.   (4)   install the water pump impeller onto the drive shaft, and slide them up out of the way.    (5)   Install the rear thrust washer engaging the 2 outer ears that do not extend all the way into the center prop-shaft hole (TIP HERE, grease the rear surface with trailer axle grease) which helps stick that thrust washer so it will not slip during the other process and you can later then install the prop shaft easier.   (6)   Now the impeller can be pushed down, aligning on it's drive pin (.092" X .565").     (7)   Now with the drive shaft down enough to install the drive shaft thrust washer and drive gear in position the bottom square of the driveshaft, (aligned to match the shaft cotter pin hole.    (8)     Put in a new cotter pin (3/32" X 1 1/4"), rotate the gear and spread the cotter pin tails into the groove of the drive gear.  (9)   Then rotate the impeller vanes in the proper RH rotation into the water pump  housing and slide the upper water pump plate and cavitation plate up against the exhaust housing.     (10)   Slide the lower unit assembly up into the exhaust housing, feeling for the crankshaft spines with the driveshaft.  You may have to rotate the flywheel slightly before you get them, aligned.  Once the shafts are aligned, (you can tell by with it in gear, buy turning the flywheel), the gears will be turning    (11)   Install the (2) 5/16" nuts on the exhaust housing studs     (12)   Install the reverse gear bronze thrust washer (centered), these ears are shorter, not going all the way into the center prop shaft hole ( grease this washer with boat trailer grease to help hold it in place while you work on the rest) to ensure this washer stays in place, if the washer gets out of place, you may well have to go back, disassemble and then reposition the thrust washer. (13)   Install the reverse gear.  (14)  Install the prop shaft.   (15)   Install the forward gear.  (16)  Then finish installing the forward bronze thrust washer in the nose cap, again, smearing some boat trailer grease on the front mating surface to hold it in place).    (17)   Install your new nosecone gasket onto the nosecone (cemented by using #2 Permatex).    (18)   With the shifting lever in neutral, and the nosecone as close as possible to the gearbox, make final minute alignment of the shifting rod connector nut (you may have to move the shifting lever slightly) to make this alignment.  Slide the nosecone tight against the gearbox and install the 3 screws (be sure that the shifting rod connector nut does not rotate and not connect with the nosecone shifting fork).     (19)   Add the 90 weight gear oil by adding it to the bottom (GREASE) fill hole and until it starts coming out the vent hole.  Replace the vent hole FIRST, (by doing this, you block the vent hole, creating a slight vacuum so the new gear oil doe not ruin out as fast before you get the fill plug screw in)  then remove the oil pump and replace the fill plug.

    In the LH photo below, you see a simple lathe operation being performed to facilitate installing the prop-shaft if the inner bronze thrust washer is slightly misaligned.  This edge was very slightly chamfered to help facilitate reinstallation of the prop-shaft.  While in the lathe, I also polished the shaft's seal area with 400 emery cloth (seen in the LH photo below as a dull 3/16" ring).

 

Here we see the sharp shoulder edge being slightly broken to a taper on the outer edge	Here is the relationship of the nosecone/rear gearcase  (the hub between the parts is only for the support of the nosecone for the photo)

 

   The gasket between the gearcase and the nose cone was made from .025" thick gasket material, by laying the material on the nosecone,  getting a good impression (best when there was a slight amount of old gear oil) then judiciously cutting away what was excess with scissors and a sharp knife.  Just before final assembly it was Permetexed onto the nosecone to maintain it remaining in place adding to it's stability.

    Propeller ;   Here is an excerpt from the factory service manual.   SLIP CLUTCH PROPELLER The hub of the propeller contains the Saran slip clutch.  Should an underwater obstruction be hit, the clutch allows the propeller to slip, instead of cutting the shear pin.  It has been pre-set at the factory to slip when the twisting force acting on it exceeds the specified torque for the particular horsepower size.  Ordinarily it will require no further attention. Adjusting lt is however, simple.  Instruct your customer to consult his Owner's Manual for adjustment. ??

 

    As additional protection to the drive and propeller shafts and other mechanism of the motor, a stainless steel shear pin is used to position the propeller on the propeller shaft. If this pin shears, the motor will run as if in neutral, regardless of what gear it is in. The motor should be shut off immediately, the propeller removed, and the pin replaced.

 

    This motor uses a shear pin in the front of the propeller, but while looking at the service manual, it mentions 2 different prop slip clutch types for this year.  So next was pull the prop and see which one this motor has.  The manual mentioned an adjustable clutch was used from about 1950 on, but if the motor was used in salt water, this adjustable unit could become seized if not inspected frequently.  It did also say the LATE 1952s used their simpler "Salt Water" version of this clutch, which is what I find is what this motor has.  GOOD DEAL for me here.

   This clutch was simply 2 opposing hardened aluminum cones (male/ female) with a .056" plastic sleeve that fit between the inner cone and outer (being the inner part of the prop).  Just tighten the prop nut for your slip adjustment.   However, in the short time that I had this apart, this plastic showed signs of deterioration (like chunks falling off if even slightly bumped).  Here I ordered a 12" square X 1/16" (.062') thick piece of Delrin, which I then made a template out of thin cardboard of a similar thickness to fit in between the two, then transferred those dimensions to the Delrin, providing a start for a new slip clutch.

 

    Before starting, both the male and female cones were cleaned and sanded down with 220 grit sandpaper.

 

   This process had to be done in steps.  Working this plastic was accomplished by cutting the material out using a metal bandsaw, heating the material somewhat using a electric heat gun to get the new material bent enough to get it into the female part (the prop).  Then by heating everything, (the material, prop and inner cone, again with the heat gun), I pushed the material deeper into the prop.  And again pushing it deeper as it took shape into the prop to get better final alignment as I pushed in the inner cone.  Once there, then heat it all again, and let them set for a while until they cooled off.

 

    As seen in the LH photo below, the dimensions are 4" overall tip to longest tip, 3 3/32" for the shorter overall, and 1" for the vertical width of the part.   With this standing up on edge the overall height from the lower tips to the center highest point of the arch is 1 1/2". 

 

    One suggestion is leave the overall length of the ends slightly longer by 1/8" or so for your final fitting.

Here we see a light cardboard fitted pattern & the layout on new material	Here are the old plastic clutch, and the new one

 
  The good one thing here, was even as I had to get this new clutch material a bit thicker, or the original had been worn down (.007"), or if placed differently in the prop, the prop nut cotter pin was an easy fit because the hole in the prop shaft was not a single hole but a slot clear to the rear of the threads on the shaft.  Thereby making for an easier cotter pin alignment if the new clutch took up more space because of it's slightly thicker material.

 

     Convert to a Flushing System ;

  While I have it this far, after reading the service manual, which gave diagrams/dimensions on how to modify the lower unit to use a modern threaded adapter to flush/run the motor using city water and a flushing adapter to a garden hose, seemed like a good idea, but alter it to use the 3/8" threaded adapter currently used on many motors to flush them.  From the service manual, it gives the exact location to drill/tap/modify the lower unit below the water pump intake to where I am able to utilize the later screw in flush adapters on this motor.  After inspection of this gearbox housing, the factory recommended location for drilling for this adapter is in a drain cavity for the water pump to keep it from freezing (and breaking the housing) during COLD weather.

 

   Mercury sells a flushing adapter that uses a 3/8" National Course bolt thread on one end and a female garden hose end on the other, as seen in the photo below.

 

    Mercury's Quick-Silver part number is  # 24789A1 for the brass version @ $26.68 with the actual name being "Flushing Device".  Also OMC Johnson/Evinrude uses the same adapter to back-flush for many of their outboard motors made from 1993 to 2007, but for some reason it is not readily located on their parts listing.   These adapters also fit about all of the Japanese outboards that use a back-flush system.

 

Mercury Outboard Flush Device  #C-24789A 1

 

   In the photo below, you can see the small drain hole directly below my new threaded plug.   This plug was made from a stainless steel  3/8" X 3/4" hex head bolt that was modified in my lathe for a lesser protrusion and a screwdriver slot then cut.  The threads were also shortened to about 3/8".   And there probably needs to be a thin Nylon washer under it, not to seal the cavity, but to keep the plug screw from loosening.  OR, you could purchase OMC drain/vent plug and washer, or the Sierra Marine equivalent #18-2387 - Drain Plug Slotted, and #18-4248 - for the Washer.

 

Here we see the flush modification

 

    Finished Product ;   I was glad that the powerhead was still in good enough shape that I did not have to delve inside it on this project.  A very welcome situation.

 

    The good part about this whole project was that I never broke off any stuck/seized bolts.  The design was simple but effective, as to producing a high grade, economical product. (Which in some cases can be too simple and frail).  And it just proves that even at my age of 85, and with many of these restoration projects under my belt, I still learned a few things.

 

   Now the question is do I try to find a matching paint AND new decals?  The paint should not be a real issue, however the decals are another story as this size and year if motor appears to be very specific to itself.  And there are probably not a lot of these motors out there, especially in a good enough condition to copy the decals from. 

 

   Therefor, I finally decided to leave it as is, It does not look bad from a distance, but up close she shows some evidence of it's 70 years of age (a few wrinkles, but no broken bones), mainly the paint shows it's age and some rust on the top of the fuel tank.   But by and large, a good representation of years gone by.  And it will push my also restored 1968 12' aluminum skiff along nicely just the way it is.  It may even bring back memories on a sunny afternoon on a local lake.

Here we see the finished project

R Recommended Fuel / Oil Mix :   The reason for mixing oil with the gasoline is to lubricate the inside of these 2 cycle motors.  The formula for the ratio was/is governed by the internal construction of the bearings, mostly the connecting rod bearings.  In early years all bearings were bronze, and requiring more oil in the fuel mix.  As time and engineering improved, the rod bearings transgressed to needle bearings.   The main bearings also changed to either ball or Torrington caged needle roller bearings, which could be slid onto the top and bottom of the crankshaft.  The bug here was the center main bearing, as it needed to be split to fit onto that crankshaft journal.  Some still use bronze for the center main, but others use loose needles.  Loose needle bearings work, but are have an issue installing them correctly.   Essentially the more ball/roller bearings the motor has the less oil it needs.  If you run a old bronze bushing motor that was designed for 24-1 mix on the newer 50-1 mix, in all likelihood in a short period of time, the connecting rod bearing would not be lubricated enough AND it will seize onto the shaft, usually breaking the rod and sometimes before the rotation stops, it can blow a hole in the block because of the rod now flopping around with not any spare room for it.

   The formula shown below will be on all modern 2 cycle oil sold in the last 50 years or so.  On most all of the pints and quart plastic bottles ofTWC-3 oils there will be a narrow clear vertical window on the edge of the bottles.  On the sides of this window will have numbers representing Ounces and Milliliters for other parts of the world.  Or you can purchase special measuring containers showing different ratios and the amount of ounces needed.
 
   If your motor is to where you have to mix the oil, you need to know how much gasoline you will be needing, add the oil before you fill the fuel tank so that the oil mixes better that just dumping it in after you fuel up.  However if that is not possible, guess, then add a majority of what you think it will take, fuel up and then add the rest matching the amount of gasoline you took on.  If you are using portable fuel thanks, before hand, when you fill it, add 1 gallon at a time, use a clean 3/8" or 1/2" dowel, mark the dowel at each gallon and use it as a measuring stick.  This way you can refill a partly full tank with the known amount of oil.

   A quart has 32 ounces of oil in it.  So for a portable 3 gallon tank normally used on these smaller motors, to fill it using the 50:1 ratio would take 8 ounces, (1/2 pint) or 1/4 of the quart.

FUEL MIXING TABLE
Gallons of Gasoline	Gasoline to Oil Ratio
	Ounces of Oil to be Added
	16:1	24:1	32:1	50:1	75-1	100:1
1	8	5	4	3	2.5	2
2	16	11	8	5	4	3
3	24	16	12	8	6	4
4	32	21	16	11	8.5	6
5	40	27	20	13	10	7
6	48	32	24	16	12	8

 

    After getting it running and the carburetor adjusted, it starts on second pull.  To be sure that it would run on my on the water fishing trip, once I got it warm and set at an idle (trolling speed), I let it run in my test barrel for 1/2 an hour.    It then was used on a fishing trip to Riffe Lake, pushing my 12' StarCraft aluminum boat nicely.