Read These Plugs?
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When did you pull these I.E. after idle time, killed on WOT, killed on a steady cruise mid throttle. Im guessing pulled after a idle. I have not read your other post nor know where you posted it, maybe you gave more info on it.
Anyway, I'm no mechanic and here is a link that may help.
http://www.centuryperformance.com/spark2.asp
Note: should always put anti seize on your plug threads!
Plugs were removed following several minutes of agressive riding and a few minutes of ldling.
98 carb'd 1340 motor with mild cam (.5" lift, 240 dur) V & H Short Shot and SE filter.
Steady-state mid-RPM cruising I get an occasional miss (once ever 5 seconds or so, but not like "clockwork") and occasional popping through the exhaust.
There's no x-over between pipes and the inside of the rear cylinger exhaust pipe is noticably (but not dramatically) blacker than the front.
On cold idle, rear cylinder doesn't seem to fire fully as evidenced by the sound of a hard "hit" on the rear cylinder every fifth revolution or so (place your hand an inch from the exhaust and you can feel it hit harder).
Compression is great and within 3 lbs per cylinder.
Wires are Accel. Rear wire (shortest one) has 60-ish ohms resistance, front has 250-ish ohms.
The timing "seems" about right, but it's so damned hard to really see those marks. It does seem to wander a bit, but I associate that (perhaps wrongly?) with loping at ide.
Rear cyl spark pug looks like it's leaner than the front but I hear that's normal (rear cyls run hotter, no?). Front plug has a region of dark black on one edge of the insulator, rear cyl has a region of dark tan. I assume this is just indexing and is normal for these motors?
So... what do you think?
Thanks all, for your feedback. Mopar and Reese: Here are the missing details.
Plugs were removed following several minutes of agressive riding and a few minutes of ldling.
Wires are Accel. Rear wire (shortest one) has 60-ish ohms resistance, front has 250-ish ohms.
The timing "seems" about right, but it's so damned hard to really see those marks. It does seem to wander a bit, but I associate that (perhaps wrongly?) with loping at ide.
Rear cyl spark pug looks like it's leaner than the front but I hear that's normal (rear cyls run hotter, no?). Front plug has a region of dark black on one edge of the insulator, rear cyl has a region of dark tan. I assume this is just indexing and is normal for these motors?
So... what do you think?
Seeing as your rear plug (60 ohm wire) looks like a average 14/1 burn ratio and your front plug (250 ohm wire) appears to have a rich or non complete burn look, I would seriously look into those resistance specs. A check for a vacuum leak is also a very good idea.
Hope you figure out your issue and get the worry out for mind at ease long rides, take care.





