B&S 12H802 coil air gap

[cadman60]

I have a JD JS60 push mower that has a B&S 12H802-1769-E1 engine on it. I just bought a replacement coil for it, p/n 590454. I've looked high and low and can't find the specification for the air gap between the coil and the flywheel. Can anyone provide me the gap dimensions? Thanks for your help.

[KE4AVB]

Air Gap .006-.010 in (.15-.25 mm)

Most us use a standard business card to set this but above is the spec setting.

[NO0C]

https://drive.google.com/drive/folders/0B-g4TpKUJnh7bEJwRjlrTnFmVWc

Manual is 270962 in that list.

.006-.010"

GL

[cadman60]

Thanks guys for the info. I used the B&S tool #19368 to test the coils. Old one indicated no spark. I then installed the new coil and set the gap at 0.012" just to see if the new coil would spark and it did. I've seen on the internet where guys check a coil using a multi-meter. Can you do that? If so, what is the range in ohms of a good coil? Thanks again for your help. I have some business cards I'll measure just to make sure they are in the range.

[KE4AVB]

You only measure the resistance of the secondary windings which the high voltage lead side. The primary of a Magnatron coil can't be checked due to electronics involved. The spark tester is about the only to verify if a coil is working or not. Basically Go/No Go test. Now the older points coils and those that uses a separate ignitor can be checked.

[bgsengine]

I have some business cards I'll measure just to make sure they are in the range.

If you got an OEM coil in the OEM box it should include an instruction sheet (or two) one of which is printed on heavier pasteboard and that sheet is also meant to be used to set the coil air gap (Says so on the instruction card, on some of them, in fact) and often a piece of the box torn off will be perfectly suitable for setting air gap - the box is usually around .010 - .012 thickness

[38racing]

looking at ms3992 I didn't realize coil gap was not same range spec for all engines.

[KE4AVB]

I tend go by this or other specs sheets. As the actual gauging I tend go with minimum gap setting but use step up as a NO GO test. IE say the setting is .006-.010, I set at .006 and see if a .007 feeler gauge will go or not. But a middle of the road setting works for most.

Now OHV valves I do the same thing using the minimum clearance but when it comes the L-heads I reverse the procedure using the maximum setting and use next size up as a no go. This is because OHV valves tend to open up the clearances where L-heads valves tend to close up clearances as these engines valve train wears. Of course with either style engine it is important to hand cycle engine through a few turns so things settle in before checking the final setting.

[KE4AVB]

I might add using a middle of the road approach on coil air gap can also be good since the flywheel might be a hair off too one way or the other affecting ignition timing a little.