In my seemingly never ending search to lower the stop and go temp of my 74
Spitfire (1500) I'm looking at the timing as some have suggested. My car
has the thermostat controlled vacuum switch on the lower radiator hose,
which I think means that the distributor is the vacuum retard type. Should
I do the timing with the vacuum line connected or disconnected to the
distributor? Also, should the idle RPM be set with the vacuum line
connected or disconnected. The idle speed increases a lot when the line is
disconnected. The specs call for the timing to be set at 2 degrees ATDC.
Would I be better off for cooling purposes to advance the timing a little?
I'm even more confused on how the vacuum switch is supposed to work. I've
tested it under varying temps and RPM's and it appears that it's constantly
suppling vacuum to the distributor which tends to retard the timing quite a
bit. Setting emission controls aside, would I be better off getting rid of
the vacuum switch and run the car without any vacuum to the distributor,
say with a 10 degree BTDC timing setting?
Thanks!!
Barry H. Adams
74 Spitfire (1500)
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