Listers,
You may recall a month ago I posted that my 1275 had
gone weird driving home from work (car revved like
crazy, then made no power, gas spitting out carbs,
etc.). After a month of distractions, I got into it
the other night and was not too happy with what I
found. The engine is a 1275 with a road cam, less
than 2000 miles on it. The engine was broken in
properly, and the cam was run in properly.
Good news was that the block looked excellent. The
cylinders were clean as could be, with the honing
pattern visible perfectly. Bad news is on the #3
exhaust valve, the adjusting nut on the valve had
backed completely off the screw. The valve stem was
beat up pretty badly, with the stem mushroomed beyond
the diameter of the guide. This I can understand, but
what really disturbed me was the condition of #1 and
#2 exhaust valves as well. Both these stems were
showing signs of wear as well. I assume the exhausts
wore first because there is more effort for the rocker
to open them against higher cyclinder pressure? The
head is off the car right now, but I will check
pushrod height relative to deck height to see if the
lifters / cam are ok.
When the engine burped, what happened was the throttle
cable stuck, and the revs shot up. I believe I caught
it by 6,000 RPM, but I'm not sure. The engine would
normally rev to 5500 no problem. I adjusted the
valves 3 times prior to this incident, and clearances
were always near correct (.017" for this cam). The
valves and springs were retained from the original
engine; guides, seals, rocker assembly are new. Does
anyone have any ideas, and has anyone seen this
before? The cam is more radical than stock, but only
mildly so (similar to a Kent 266). Right now the
immediate fix is easy and cheap, but I'm afraid this
is a systemic problem.
Thanks,
Ron
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