Try advancing the timing.
I would say you could try advancing the timing a bit. A couple of things tell me this:
1) It sounds quieter when running on WMO. Retarded timing will sound like this.
2) It tends to lose 1 or 2 MPG on wmo. Retarded timing will do this. Too far advanced timing will also do this, but it will rattle like a *****!
WMO actually has a higher energy content and by setting the timing properly should net you a 1 or 2 MPG gain.
It should smoke less too.
Try advancing it a degree or two, and report back with your findings. It is best to set the timing with a meter as stated above, but you don't absolutely NEED one. Just make sure you make a mark on the line between the IP and the housing. A center punch or cold chisel works well for this. This way if the timing change doesn't work out, you can return to your starting point. 2 degrees is equal to .030 of an inch. For reference, the thickness of an American dime is close to .055"! A Canadian dime is only about .050". See pics below.
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