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CORE PLUG HEATER - CO-210
Core plug heater and power cord

If you have need to operate your MG in cold weather, you may want some means of preheating the engine for easier starting or quicker warm up. If you have access to an AC electrical outlet, this little jewel can work wonders. It is by far the simplest and most effective device for the job. It is a Core Plug Heater. For the MG you need 1-5/8" diameter. Expect the part to cost about $20 to $30-USD at your local auto parts store.

Core plug heater Install this in the side of the engine block in place of the center core plug where it will fit between the #2 and #3 cylinder liners. It has a rubber O-ring for the outer seal. Inside there is a T-bar with a center screw to secure it in place. To remove the original core plug, drill a hole in it and pull it out with slide hammer (a.k.a. dent puller) with coarse sheet metal screw.

The heating element is a cowl rod resistance heater, a simple device capable of 100% efficiency at converting electrical power into heat. These may be available in 300 to 1000 watt models. For the MG engine 300 watts may be enough down to -10dF if you leave it on for several hours before starting. A 500 to 750 watt unit can warm the engine from -20dF to easy starting temperature in a few hours. Higher output is not recommended for the small engine.

Coolant will circulate within the engine block by thermal convection with warmed fluid rising to the cylinder head and cooler fluid falling to the lower area of the engine block where the heater is located. The warm cylinder head will also warm the carburetors slightly for easier starting. Warm oil in the journal bearings makes for easier cranking. The warm engine reduces wear on start up. Oil in the sump may not be warmed appreciably, but there is really no need to waste energy there unless the temperature falls far sub zero (in which case you might consider using synthetic oil).

If you were so inclined you could rig an AC outlet with a 10 amp relay timer or even a remote control to switch the heater on a few hours before you want to drive. If you use it in warmer weather or leave it on for extended times, the cooling system serves to prevent anything from overheating. If the coolant should happen to get warm enough the thermostat will open to allow thermal convection circulation through the radiator to easily dissipate any excess heat.

Cost to operate depends on your local utility rates. If your electric rate averages 10 cents per kilo-watt-hour, the 500 watt model would cost 5 cents per hour to operate. If you left it on constantly, $1.20 per day. A 750 watt unit operating 3 hours daily would cost less than $.25 daily, and only when you actually use it.

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