Some advice from Covington Engines on how to manage a 1340
Full Throttle Take-Off: This engine is equipped with a float type carburetor that supplies more fuel to the engine during take off and during very high power output than the engine actually needs for power production! This extra fuel is metered to the engine through an economizer valve (actually a fuel enrichment valve) with its own jet. This extra fuel serves to cool the cylinder heads during high power application. If a pilot doesn’t use full throttle for take off, he is actually leaning the engine and possibly over heating the cylinder heads and exhaust valves! This can lead to increased potential for head failure and sticking valves. If you just can’t stand application of full throttle please consider 34.5 to 35 inches as a bare minimum!
10 Spread for Cruise: Develop a practice of not exceeding a “10 Spread” between engine revolutions per minute (RPM) and manifold pressure as a maximum power setting for RPM used. Example: 2000 RPM – 30 inches manifold pressure maximum. 1900 RPM – 29 inches MP maximum. Lower manifold pressures can be utilized but beyond certain limits may not be practical. Piston ring flutter at manifold pressures below 23.5 inches can cause accelerated piston and ring wear. Piston ring flutter has been known to produce very high crank-case vent pressure and related heavy oil venting overboard! (Note, constant speed prop required, which we don't have yet. 1750 RPM recommended for fixed pitch prop.)
Approach Minimum MP: It is recommended procedure to maintain one inch of manifold pressure for every one hundred propeller R.P.M. while on approach for landing. Example: 1700 RPM – 17 inches manifold pressure minimum. If a pilot ‘chops’ the throttle during descent to land he will ‘super cool’ or ‘shock cool’ the cylinder heads. This sets up tremendous stress in the aluminum head, and if done habitually, can lead to cylinder cracking.
Pilot Tip: Check your manifold pressure gage against reported field barometric pressure while the engine is shut down, they should match!
General information about the Wing42 Lockheed Vega.
1 post • Page 1 of 1