Sorta long--neither my wife nor my dog wand to hear about this...
I flung the gauntlet at Murphy again on May 21st.
I had stated my roadster was "running a lot better than it had in a long
time". I should have known better, for I have not been able to drive it
on the road until today. Murphy got me good.
Before making that "ill-fated" statement, I had accomplished a complete
redo of ignition with both Pertronics and overhauled points ignition,
new NGK plugs, set and reset valve clearances, adjusted and balanced the
carbs
Not leaving "well enough alone", I had proceeded to make a minor change
to crab. #2 in a further attempt to keep it from blackening my #3 and #4
plugs. I had been successful in getting it a lot leaner than it had
been.
Immediately thereafter, the engine began missing under load.
Since the last thing I had done was to carb 2, I returned it to its
state when the engine was running well. Didn't resolve the problem.
The miss was so bad, I thought maybe something happened to cause loss of
compression of a cylinder. Then I commenced a number of compression
checks, wet and dry. Mean compression wasn't great, about 135, and one
cylinder, #1, was lower than the recommended 10% of the mean, being
about 120.
The idle performance was still pretty good, and at 800 rpm it really
wasn't obvious that it was missing. Could remove #4 and #3 plug wires
with only a slight decrease in rpm. Could remove BOTH 4 and 3 and the
engine still ran pretty well. Removing 1 or 2, with 3 and 4 reconnected
resulted in "stumbling".
So, went back to carburation, thinking maybe I could get it to run as
well on 3 and 4 alone, as it did on 1 and 2 alone by better adjusting
carb. 2.
Well, that didn't work.
So, what could it be? Ignition? New, carefully gapped plugs, two
different distributors giving similar results. Sure didn't seem like it
would be ignition.
"Grasping at straws" decided to try previous (used) plugs in cyls. 3 &
4.
Problem solved, #3 turned out to be the culprit
Dave,
'68 1600
Kailu-Kona
p.s., I refuse to commit as to how it's running now, but I'm smiling a
whole lot.
p.p.s.. I've never had a "bad" spark plug before. I still didn't
believe it. Put the plug from #3 in #2 and the missing returned. So
I'm running with one used plug.
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