Bracket Air filter element PN and spark plug recomendation
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- Name: Tamer A
- Location: KSNA
- Aircraft Type: 1946 C120 O-290-D
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Re: Bracket Air filter element PN and spark plug recomendation
Speaking of rotating, Any special sequence? Or just top to bottom and bottom to top? (On the same cylinder).

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- Name: John C
- Location: KLCI, NH
- Aircraft Type: 1946 C140/C90
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Re: Bracket Air filter element PN and spark plug recomendation
Magneto systems fire half the plugs by making the center electrode positive and the other half negative. You want to reverse the polarity (to even out the electrode wear) and move the plug from top to bottom, or vice-versa.
If you have a plug rack, take them out and put them in the rack like this:
Top .... - 1 2 3 4
Bottom - 1 2 3 4
Next, swap 2 with 3 and 1 with 4 in each row, then install the ones from the top row in the bottom and the bottom row in the top, so, 1 top goes to 4 bottom, 2 top to 3 bottom, etc.
If you have a plug rack, take them out and put them in the rack like this:
Top .... - 1 2 3 4
Bottom - 1 2 3 4
Next, swap 2 with 3 and 1 with 4 in each row, then install the ones from the top row in the bottom and the bottom row in the top, so, 1 top goes to 4 bottom, 2 top to 3 bottom, etc.
John Cooper
www.skyportservices.net
www.skyportservices.net