1951 Briggs Model 6S


According to the serial number this engine was manufactured in February of 1951. 



This engine had been out in the weather for some time.  It took the heavy puller to get the small pulley off the PTO end of the crankshaft.  To get the flywheel nut loose I use an electric impact gun.  Left hand thread on most of the old rope start engine.  Clockwise to loosen.


Next the rusted tight muffler was tackled.  To remove them I cut the pipe off close to the block, leaving about 1/8 sticking out.  Then I make 3 cuts not quite to the threads.  Using a chisel I break the three sections in and remove them.  If your careful the threads will be undamaged.

Next issue was the fuel tank.  It's rusted through in spots.  I'll just replace it with a tank from the spares box.

I don't usually prime my engines before painting,  but because the sheet metal is deeply rust pitted I decided to prime.  Several coat of sanding primer was used to fill the pits and make the surfaces smooth.

Here is the clean block and base.  For as rough as this little engine was, it cleaned up nice.  At this point the cylinder has been lightly honed,  and the vale seats have been lapped.


After painting the assembly work.


The internal parts are assembled with the bearing cap screws torqued to 110 inch pounds.  The cam timing marks can be seen in the middle picture.  The third picture shows the assembled valve springs and keepers,  with the internal breather in the middle.  The valve stem of the exhaust valve was ground to achieve a clearance of .014".  The intake valve was OK as it was at .007" clearance.

The base in then mated to the block with a hand cut .030 thick gasket.

The high tension wire was too far gone.  I made up a new one using 7MM copper core wire and a new push on plug end.  Then the mag plate was mounted to the block using a .015" gasket to set the proper crankshaft endplay.  Points are set to .020 gap.  The magneto is set to .010 clearance to the flywheel.  I checked for spark at this point.  It's there,  not great but there is spark.

With a new head gasket in place the the rest of the engine was assembled.  Head bolts are torqued to 140 inch pounds.  Flywheel nut is torqued to 55 foot pounds.  The decal is another home made reproduction.


The Finished Pictures

And a short video of it being started up.

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