Specifications

To test for clogged fuel line, loosen fuel line nut at
carburetor slightly. If line is open, fuel should drip
out at loosened nut.
COMP RESSION
Compression check with a commercial compression test gauge
can show whether or not an engine has faulty compression.. We
do not consider it practical to publish a PSI compression figure
because of the variables involved: engine condition, method of
testing, and RPM of test. Our recommendation is that whatever
gauge test is performed, a 10% variance between cylinders would
indicate leaking rings, leaking valves or any of the following:
Cylinder dry due to engine having been out of use for some time.
See "Restoring Compression’, Page 15.
Loose spark plugs or broken spark plug. In this case a hissing
noise will be heard when cranking engine, due to escaping gas
mixture on compression stroke.
Damaged cylinder head gasket or loose cylinder head. This will
likewise cause hissing noise on compression stroke.
Valve stuck open due to carbon or gum on valve stem. To clean
valve stems, see ’Valw’.s’, Page 22.
Valve tappets adjusted with insufficient clearance under valve
stems. See "Valve Tappets’, Page 23.
Piston rings stuck in piston due to carbon accumulation. If rings
are stuck very fight, this will necessitate removing piston and
connecting rod assembly and cleaning parts. See "Piston and
Connecting Rod’ Page 21.
Scored cylinders. This will require reboring of the cylinders and
fitting with new pistons and rings. If scored too severely, an
entirely new cylinder block may be necessary.
IGNITION
See ’Magneto Ignition Spark’, Page ll or ’Distributor-
Battery Ignition’, Page 12: No spark may also be at-
tributed to the following:
Ignition cable disconnected from magneto or spark
plugs.
Broken ignition cables, causing short circuits.
Ignition cables wet or soaked.
Spark plug insulators broken.
Spark plugs wet or dirty.
Spark plug point gap wrong. See Page 15.
Condensation on spark plug electrodes.
Magneto or distributor breaker points pitted or fused.
Magneto or distributor breaker arm sticking.
Magneto or distributor condenser leaking or grounded.
Spark timing wrong. See ’Magneto Timing’, Page 12,
or "Distributor-Battery Ignition’, Page 12.
ENGINE MISSES
Spark plug gap incorrect. See Page 15.
Worn and leaking ignition cables.
Weak spark. See ’Magneto Ignition Spark’, Page l l,
or ’Distributor-Battery Ignition’, Page 12.
Loose connections at ignition cable.
Magneto or distributor breaker points pitted or worn.
Water in gasoline.
Poor compression. See ’Compression’, Page 17.
ENGINE SURGES OR GALLOPS
Carburetor flooding.
Governor spring hooked into wrong hole in lever. See
’Governor Ad/ustment’, Page 24. Governor rod incor-
rectly adjusted. See ’Governor/td/ustment’, Page 24.
ENGINE STOPS
Fuel tank empty.
Water, dirt or gum in gasoline.
Gasoline vaporized in fuel lines due to excessive
heat around engine (Vapor Lock). See "Stopping En-
gine’, Page 9.
Vapor lock in fuel lines or carburetor due to using
winter gas (too volatile) in hot weather.
Air vent hole in fuel tank cap plugged. Engine scored
or stuck due to lack of oil.
Ignition troubles. See ’Ignition’, Page 17.
ENGINE OVERHEATS
Crankcase oil supply low. Replenish immediately.
Ignition spark timed wrong. See "Magneto Timing’,
Page 12, or "Distributor-Battery Ignition’, Page 12.
Low grade of gasoline.
Engine overloaded.
Restricted cooling air circulation.
Part of air shroud removed from engine.
Dirt between cooling fins on cylinder or head.
Engine operated in confined space where cooling air
is continually recirculated, consequently becoming
too hot.
Carbon in engine.
Dirty or incorrect grade of crankcase oil.
Restricted exhaust.
Engine operated while detonating due to low octane
gasoline or heavy load at low speed.
ENGINE KNOCKS
Poor grade of gasoline or of low octane rating. See
’Fuel’, Page 8.
Engine operating under heavy load at low speed.
Carbon or lead deposits in cylinder head.
Spark advanced too far. See "Magneto Timing’, Page
12, or "Distributor-Battery Ignition’, Page 12.
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