Rich Mixture Problem

[tporter]

I'm in finishing stage of My -4, When running the engine I have to have the mixture approx. 3/4 back to get it to run smooth at idle. At 1500 about the same. If I go full rich the eng. floods, lots of black smoke. I've tried 3 diff. carbs, no change. I'ts an 0320-E2D 160 HP Any advice would be greatly appreciated.

[R.P.Ping]

If you have a primer system disconnect it and try again.

[tporter]

no primer on it.

[robertahegy]

Assuming the carburetor floats are OK and the mixture just needs tweeking, you should set the mixture screw in accordance to the procedure in the lycoming manual.

If you don't have a manual here's how;

Set idle speed (700) with engine at operating temps. Pull idle cut off and observe rpm. A rise of more than 30 rpm indicates rich condition, No change indicates a lean condition. Turn screw in to lean and out to enrichen. Reset rpm to 700 and retest idle cut off. Adjust until you get about 20-30 rpm rise just as engine cuts out.

Do this only after you are sure there are no other problems like bad timing, plugs, leaky carb, etc.

Hope this helps,

Roberta

[szicree]

What is known about the overall health of the engine, in particular compression?

Steve Zicree

[Mark Burns]

You may not be getting enough air into the carb.

Mark