[TR] steady Tr4 idle

[Carl Sereda]

Hi Guy,
(Just thinking out loud here).. Since you recently rebuilt your motor it seems
unlikely timing chain and tensioner already worn..  I have a newer low mileage
dizzy 'drive gear', and noticed it is copper plated. My old original gear
shows copper well worn through into the steel teeth.  ..your gear may be worn
beyond limit, length-wise.. but also tooth-wise.. allowing a bit of chatter
with the cam gear, and affecting your idle..
Rather than searching for the rare gear.. wonder if having your part heavily
re-copper plated would resolve both 'worn beyond limit' areas..
Good luck,
Carl
'63 TR4 since '74


But I was still getting a "jumpy" idle, normally varying between 800-900 RPM,
occasionally dropping into the 700s..

So, on a suggestion from Randall I went and got myself a timing light and
found the timing is jumping, to the advance side.
Hmm.. maybe the dizzy gear end float.
Checked it.  Just over .007.. just exceeding the upper limit.