Uneven mixture distribution with carburetor.

[Fugitive]

O320-E2A installed in rv6. Wide open throttle 13-13.5 gallons per hours. Pretty even cht’s and egt’s. As soon as I come off WOT throttle cylinder 3 and 4’s egt’s rise substantially while cylinders 1 and 2 stay relatively cooler. I’ve checked and replaced intake boots and gaskets with no change. Borescoped intake tubes down to carb and found noting notable. Bypassed primer system with no change. Top plugs are on Bendix mag and bottom plugs are on electro air electronic ignition. Spark plugs are as shown in pics. Cylinder 1234 from left to right in pic. I’m not sure if this is a problem or the nature of the beast. Considering sending carb for bench test/rebuild. Thought?

 

[rocketbob]

Main jet is ahead of the throttle door so the door further deflects the stream of fuel to one side as the throttle is closed. Nature of the beast.

 

[Norman CYYJ]

Try just backing the throttle off and out of the accelerator jets that are dumping a lot of fuel. Then check you fuel flow and temps.

 

[scard]

Normal. Throttle position, + carb heat position and you'll find a magic spot at a given altitude. Always a good time with a carb. It just works, but you have to stick your tongue out just right.

 

[Dbro172]

Get used to it. Drove me bonkers too. Like @scard says, small tweaks to throttle position and carb heat (disrupts the flow just right to mix the fuel air differently, same with the butterfly inside the carb). But this all varies per altitude and atmosphere, it seems.

 

[Dugaru]

O320-E2A installed in rv6. Wide open throttle 13-13.5 gallons per hours. Pretty even cht’s and egt’s. As soon as I come off WOT throttle cylinder 3 and 4’s egt’s rise substantially while cylinders 1 and 2 stay relatively cooler. I’ve checked and replaced intake boots and gaskets with no change. Borescoped intake tubes down to carb and found noting notable. Bypassed primer system with no change. Top plugs are on Bendix mag and bottom plugs are on electro air electronic ignition. Spark plugs are as shown in pics. Cylinder 1234 from left to right in pic. I’m not sure if this is a problem or the nature of the beast. Considering sending carb for bench test/rebuild. Thought?

Nature of the beast. On the plus side, carbureted engines are easier to start when hot!

 

[ve0kog]

i have the E2A as well and the same carb. 3 and 4 run leaner even at WOT. i can lean and get all 4 egts closer together at cruise but 3 and 4 peak earlier. so they run LOP while 1 and 2 near peak. i’m usually at or below 65% so that does not hurt the engine but not loving it.