Figure I post this here
Flight & Tim Avery:
I get questions quite often about "how much preheat-what kind ?" and "I preheated my engine but it just barely starts"--You need 2 things to get her going Magneto firing and fuel in proper operating.Plugs not firing is a common problem--The engine needs to be turning over approx. 200 -300 rpm to fire the magneto and get this mother started . Wet Cell batteries are not very good in this environment> I'll take a SBS-J16 any day on the firewall.The Plugs need to be clean and good to fire properly if the Mag delivers the spark to the cylinder where a small bit of fuel (either prime or Fuel injector ) has been delivered . Engine itself should be preheated to thin oil and reduce resistance to turning over.Multi Grade ie 15/50 or such oil will start flowing to internal parts sooner. When engine starts let it idle for period maybe 2-3 min. before adding and power above 1000rpm.You can start taxi while it warms up.Oil pressure should be in green and cylinder head temp coming up. Don't pour the coal to engine until your temperatures /pressures are good. Preheat in Temps below 40 is good advice- Where I have electric power I use 2 drop lights in cowl with old sleeping bag over outside > where power is NOT available outside I've got a camp stove(fueled with 100LL) with Dryer hose to go in cowl and cover outside.Time to do this preheat varies with temperature and length of time exposed to cold environment. Best world would be heated hanger .
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Bill Reid PAMA>AMT>VHPA>
A&P/I.A.CPA Rigger,Pilot AZ50
"Have tools can travel"