If they only wanted it retarded at idle, there would be simpler ways to
do it. My TR250 had a little valve which activated the vacuum retard
with the throttle linkage. Why make it vacuum dependent? Are we saying
Triumph made these cars unnecessarily complicated, i.e. like a German
car? - Larry
On 1/12/2014 4:20 PM, Randall wrote:
>> 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
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