1961 40 HP Lark 3

Hi everybody got a couple quick questions I've done a couple searches kinda came up semi empty anyway When I'm idleling / flushing setting low idle cleaning out my engine in a garbage can does that little hole on the starboard side going into the waterpump impeller need to be underwater when in the the can? if so how much (is this the part about not being self priming) what does that really mean? and the second question is does this motor have that thrmostat system that hold back the water discharge until the engine is at proper operating temperature.



Thanks, in advance, Paul

Re: 1961 40 HP Lark 3

Not self priming means that you want the lower unit in the water, having the water level a few inches higher than where the lower unit bolts onto the long exhaust housing. The water pump in directly on top of the lower unit's surface.

The thermostat is located on top of the cylinder head under that small plate that is attached with three screws.

Re: 1961 40 HP Lark 3

Fill the trash can up as high as you can get it; at least half way up the leg over the AV plate.
The motor should have a thermostat, but some people take them out. If it's not there, put one in.

Re: 1961 40 HP Lark 3

(Thermostat Purpose)
(J. Reeves)

Many engines are considered high performance engines and demand a thermostat(s), and many smaller hp engines also require a thermostat for the following reason. The pistons actually distort/twist off round when running. The thermostat is required to keep the outer wall surrounding the steel cylinder, and the cylinder wall itself at a temperture to compensate for the distortion.

With the thermostat removed, the difference in temperture between the inside the cylinder and the water jacket quickly reaches a point whereas (in effect) you have a oblong piston running up and down a round cylinder, or vice versa. Bottom line is without the thermostat, the piston and cylinder wall could be damaged in a short period of time.

The thermostat in your car isn't there simply to have the heater function properly..... think about it.

Re: 1961 40 HP Lark 3

Thank you all for the help. Paul