On both of my cars I have 2 block heaters and an in pan oil heater wired to one plug. Also run a 180 thermostat. These are on alcohol. For the screw in plugs on my Indy block, I tapped them for 3/4 NPT and used the heaters from Jegs. On alcohol, heat is your friend. The hotter the air temp, the better the fuel is vaporized. My cars will start and run like a street car, even in 46 degree Dallas.
