Double oil fouled plugs?

[sutor623]

Well I could have had the carbs set too rich and that was part of it. Either way tightening up the idle screws really brought combustion temps up

 

[oldboat1]

Object is always to find the leanest air/fuel mix when dialing it in -- motor tells you where the sweet spot is.

If you want to, you could probably increase the oil ratio now that you have the air/fuel mix set properly. Don't enrichen the air/fuel mix.

 

[sutor623]

Object is always to find the leanest air/fuel mix when dialing it in -- motor tells you where the sweet spot is.

If you want to, you could probably increase the oil ratio now that you have the air/fuel mix set properly. Don't enrichen the air/fuel mix.

I hear ya, but she already has the 10 solid hours of breakin on her, I think I am just going to continue 50:1. I am considering putting the VRO back on her. I think that the 100:1 ratio at idle will be clean and nearly smokeless. I think these engines run best with the VRO in.

 

[jimmbo]

Thanks, I assume the biggest reason for this would be bad needle seats or floats set too high? I am sure I set the float heights perfectly so I just cant see how it would be loading up.............

Loading up at idle is not necessarily caused by rich carburation, though it certainly accelerates it. Fuel accumulates in the crankcase at low speeds simply because it falls out of suspension from not moving very fast on its way to the combustion chamber. It puddles and eventually large unvapourised amounts of gas/oil are pushed into the combustion chamber. Unvapourised gas doesn't burn well so the engine runs rough and very rich, resulting in fowled plugs

 

[sutor623]

Loading up at idle is not necessarily caused by rich carburation, though it certainly accelerates it. Fuel accumulates in the crankcase at low speeds simply because it falls out of suspension from not moving very fast on its way to the combustion chamber. It puddles and eventually large unvapourised amounts of gas/oil are pushed into the combustion chamber. Unvapourised gas doesn't burn well so the engine runs rough and very rich, resulting in fowled plugs

Thanks man, that makes a lot of sense. One thing that I noticed with double oil, and I guess the carb idle jets not set perfectly, was when I was running full throttle, and then came off plane quickly, the engine would stutter and surge for about 10-15 seconds, then would stabilize. If I came off of plane gradually and gently (as I often do) I didn't see the issue at all.