Re: Evinrude 40 help
Compression will vary if this is a rope start model (you didn't say), the faster one cranks the engine, the higher the compression (to a point). However, an electric start model, if cranking properly, should read higher than that. Let us know what you find (pistons, cylinder walls, head or block sealing surfaces) when you remove the cylinder head..... and what the compression is after you install the new head gasket.
Note that the head bolt torque is 18 to 20 foot pounds, tightened in the following sequence. The following numbers represent the head bolt locations.
9....10
5.....6
1.....2
4.....3
8.....7
The term "plenty of spark" doesn't really tell us much. With the spark plugs removed, the spark should jump a 1/4" to 3/8" gap with a strong blue lightning like flame... a real SNAP! Does it? Note that the gap is important.... using the spark plugs to test the spark is a waste of time.
If you have proper compression, spark, and fuel mixture to the combustion area, the engine has to run UNLESS the flywheel to crankshaft key is sheared (throws the engine out of time). The flywheel nut must be torqued to 105 foot pounds, otherwise the key will absolutely shear.
Possibly you are in error about the fuel mixture being present in the combustion area? If so, I would suspect that the carburetor is fouled somewhat. especially the brass high speed jet that is located in the bottom center of the float chamber.... way in back of that screw/bolt at the bottom front of the carburetor. Fuel must flow thru that jet before it has access to any other fuel passage.
