Coil Spacing

[NCMau]

I'm restoring a 12HP B&S. It was running pretty good few days ago, but today it developed a burned coil. I replaced the coil with from another similar working engine I had. It runs but not as well as it did before. My question is: what spacing should the gap be? In replacing the coil, I used the thickness of a 20 lbs paper to space the gap but I'm not sure it's the right thing. There is a 1/4" spark jump from my test plug. It fires but it's not sustainable. It acts like it's not getting gas, but I haven't changed anything in the gas area as it ran okay before. The only thing I changed is the coil. Any ideas?

 

[joemd11]

We always used a cover from the phone book. I don't know if we even have a phone book anymore.

 

[The kid]

My kids left the riding mower outside for a couple of months and was rained on several times thus developing rust on the flywheel magnets. Cleaned the flywheel and coil. Used printer paper folded in half. I let the natural pull of the magnets snug it. Locked it down. Easily slid the paper out. Fired right up.

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[Coyote machine]

We always used a cover from the phone book. I don't know if we even have a phone book anymore.

Yellow pages or white?:laughing:

Though you replaced the coil it may not be the same spec and could create the difference you're noting.

 

[PILOON]

Based on the principal as to how a coil works, the closer the better would be my opinion A weak magnet however can be a possible problem area but doubtful.
Contacts (including grounding) and good plug wire is always a must. Rust is your enemy.Add to that a new properly gapped spark plug.