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Old 01-06-2012, 09:55 AM
BogiesAnnex1 BogiesAnnex1 is offline
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Originally Posted by 396chevelle
I'll pull the plugs this weekend and put it a new set. When I pull the new set to see how there doing I'll mark them and let you know which cylinder they were firing in! Thanks for the info. WOT or Cruising speed?
Cruising at this point we're just trying to get a look at the general health of each cylinder. WOT is tougher test to do it properly I'll quote Cobalt's earlier input which is:

"If you want to get a better idea of the air/fuel ratio, you have to do a "plug chop" to show you the color. This would be done at the RPM/load where you were interested in checking, i.e. if you want to know what the a/f ratio looked like at WOT, you'd run it at WOT to do the chop. Same thing for mid-range cruise, etc. Idle mixture can be checked in various ways, but before doing any of that, the timing should be dialed in. Depending on the cam you might need quite a bit more initial timing than would seem 'normal'."

The WOT is harder to do as you need to put in a fresh set of plugs when ready to perform the test, run it for the test then kill it at the top end and coast down out of gear, then pull the plugs. They need to be inspected under a bright light and with magnification as unless there is something really, really off the insulator color changes are very subtle and difficult to see. Somewhere in some old hot rod book there is a picture of a guy doing this; holding a plug in one hand while using a hand held lighted magnifier in the other with an eye ball to the lens.

Your issues if there are any seem more general where the WOT test is after just what's happening at a specific place.

Also, keep in mind that often when a plug gets carboned up it never recovers. My wife's Sportster is like that, if she leaves the choke on too long it fouls the plugs and no amount of cleaning and reuse brings them back, you just toss 'em and restart with new, clean porcelain. This is why I want you to just put a fresh set of plugs in and put some miles on them, so we start with a clean slate to read from.

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