Hi listers.
Thought you might like to here what I hope is the end of my quest for my engine
noise. I had dismantled my distributor in search of a problem and really found
nothing obvious other that a need lube and cleaning. I was still stalemated.
I was looking at the exploded view of the distributor in the workshop manual
the other day and I saw two things that didn't match my unit. The first was
the shape of the finger on the cam. This acts as a counter weight and the tip
of the finger hits one of the spring posts to act as a backup limiting stop.
The spec is 9-11 degrees of advance and there is a 10 degrees stamped on the
cam finger. However my cam finger had a big half circle in the tip and I
noticed that there was a big dent in the spring post. This erosion of the
metal was from the weak, extended springs. I checked the length and spring
stength from specs in my Clymers handbook.
Based on some good techneque from a lister, I measured the circumverence of the
distrubutor body and marked off 4 degree marks and then measured the ammount of
advance that was being given with this erosion in the cam stop. Well I got
well over 16-17 degrees instead of 10 degrees.
The other problem was that there was a spring missing in the vacuum advance
assembley before the adjustment screw. This allowed a 1/8 " of play... that
translates to much less retard underload. The vacuum advance is supposed to
retard up to 2 3/4 degress under max load.
All that added up to almost 10 degrees too much advance under load. Well to
test out the theory, I temporily repaired the finger with epoxy and spruce
hardwood to allow only 10 degrees and scrounged up a spring for the vacuum
advance and did a test drive with normal static timing.
Yee-Hah. Problem fixed except... for slight pinging at full throtle above 3000
RPM. So today I had TRF Fedex me a new $260 rebuilt distributor. I just hope
this worn distributor has not damaged the bearings or wrist pin bushings. I
must call the PO to find out how long this had been going on.
THANK YOU to all of you who have been so helpful over the last month and half.
Brian Sanborn
62 TR4 CT16260L Groton,MA
sanborn@net1plus.com
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