[Fot] Distributor Retard

[Randall]

> This is not a racing question.  I'm sure the ignition retard is often 
> disabled on 6 cylinder Triumphs.  Does anyone know why it was used in 
> the first place?  I have always thought it was strictly for 
> emissions, 
> which became more restrictive in 1968.

Supposedly it raises cylinder pressure at idle (by allowing the throttle to be open farther at idle), and hence promotes more
complete combustion, reducing HC emissions.

>  Perhaps it improves 
> combustion 
> at low throttle such as when decelerating or when descending a hill.  

That would be the throttle bypass valve, which effectively opens the throttle even further (for the same reason).  Other cars used a
gulp valve, I'm not sure why the difference.

Randall