[TR] TR3 Timing question

[Randall]

The problem with that approach IMO is that a TR3 is designed to idle with
the timing rather retarded from normal.  That is why the factory timing spec
is only 4 BTDC rather than the more common 10-14 BTDC found on most
(non-emission) motors.  My theory is that this was done to reduce the chance
of kickback when hand-cranking the engine.

Then to compensate, the centrifugal ignition advance curve is very fast in
the region just above idle.  It also starts right at idle.

So if you set timing at idle to be optimum for that rpm, it may advance too
much when running at higher rpm.  Usually you can hear the knock from
running with the ignition too far advanced, but not always.  I'm fairly
certain that knock under high speed cruise conditions is what broke the
lands in this piston; but I never heard the knock.
https://i.imgur.com/9lMDPY9.jpg
(Rings were broken too, but I forgot to take a photo.)

Long as I'm here, here's a photo of the 6 bolts in the front pulley.
https://i.imgur.com/giozHFz.jpg

-- Randall 
56 TR3 TS13571L once and future daily driver
71 Stag LE1473 - awaiting engine rebuild
71-2-3 Stag - awaiting gearbox rebuild 

> considering the wear issues for these old cars...the best 
> procedure I've learned to trust (and has worked on a variety 
> of cars...) taught to me by an ol' timer...
>