Cold weather, really cold, has set in here, so even though the L4 is ready to maiden, it'll have to wait a couple weeks. I have skis on it, but the air temp is brutal.
I've replumbed the tubing all over the engine, and relocated the gas tank down lower in the fuselage. I really made a dumb mistake on the plumbing. I accidentally had the primer bulb supply hooked to the intake, thinking it was the pulse input to the carb. The result was sucking raw gas right into the combustion chamber! It ran, but one cylinder was spewing raw fuel. Lucky it didn't turn into a blowtorch. Also, the crankcase port served as a poor pulse source because as two pistons are moving down, two more are moving up, thus negating any pulse pressure wave that would normally be there in a 1 or 2 cylinder engine. So, this is what I did:
1) brazed a tube barb onto the intake pipe near the head of the front right cylinder. This became the pulse source.
2) I drilled and tapped for a barb right in the pump cover on the Walbro. See the arrow. The other end of the pulse tube goes there.
3). I plugged the primer bulb tube with a red plastic cap.
4. I lowered the gas tank.
After doing all that, the engine ran like a watch, very nice. Ready to maiden.
