Listers,
Eleven TR4A owners responded with spec readings off their stock Lucas
distributors VACUUM ADVANCE units. Thankyou all.
Eight owners reported;
2-6-3
Legend:
A = required vacuum to start advancing
B = vacuum at which maximum advance occurs
C = maximum advance in degrees
Three owners reported:
4-14-8
5-17-10 and
5-13-10
The minority units above; need higher vacuum to get started, can handle a
higher vacuum range, and can provide up to 7 degrees more advancement.
Which is stock? Probably 2-6-3. Which is better? I don't know enough about it
- the capability of 7 degrees more advancement might make your motor more
responsive OR cause tuning difficulties.
About halfway through TR4 production (CT17954) the vacuum unit was updated
(probably to 2-6-3) and I think it ran unchanged through the duration of
TR4-A production. If anyone has more info - please speak up.
Regards,
Carl Sereda
'63 TR4 since '74 - CT22326L
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