Hey - did you know if you click on the title of a thread it will take you to the first unread post since you last visited that thread?
but were afraid to ask: 
STOP!! Never post your email address in open forums. Bots can "harvest" your email! If you must share your email use a Private Message or use the 
smilie in place of the real @
Pretty Please - add it to our Events forum(s) and add to the calendar! >> 
More curious than anything; does the thermostatic vacuum switch allow vacuum to reach the retard unit at the distributor when the radiator water is cold or once the water is warm? The switch was already removed from my 1973 TR6 when I took ownership, with the vacuum tube going straight from the rear carb to the retard unit now.
-
Hi Guest!
You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
There are some perks with a member upgrade!**Upgrade Now**
(PS: Subscribers don't see this gawd-aweful banner
TR6 Thermostatic vacuum switch
- Thread starter Ribbs
- Start date
Share this page
poolboy
Yoda
Offline
There is a waxstat valve within the Thermostatic Vacuum Switch which prevented the vacuum from reaching the distributor's vacuum retard module when the coolant temperature reached the waxstat setting of over 200*F.
The effect was an increase in idle speed, fan speed and coolant circulation strictly due to the advance in ignition timing.
The effect was an increase in idle speed, fan speed and coolant circulation strictly due to the advance in ignition timing.
Thank you poolboy. I wonder then, without the thermostatic vacuum switch present if I wouldn't be better off just disabling the vacuum retard unit altogether. I believe that where the vacuum port is located the retarding action goes away as soon as the throttle comes off idle anyway. In that case would I leave timing at 4° BTDC at idle?
I do plan to send my distributor into BVU this winter for an overhaul including recurving mechanical advance and the addition of their advance module.
I do plan to send my distributor into BVU this winter for an overhaul including recurving mechanical advance and the addition of their advance module.
poolboy
Yoda
Offline
Retarding the ignition at idle is (was) an attempt to reduce emissions when the engine is idling...you can read a little on it here for the theory and nature of the emissions it's attempting to control.
http://www.georgiajag.com/Documents/Vacuum Advance versus Vacuum Retard.htm
If you disable it as many of us do, the ignition timing will advance as much as 14* to 16* depending upon the module, which will put the spark somewhere within the BTDC marks on your damper...10 to 12* BTDC at idle with a disabled retard perhaps.
Rob @ BVU will give you his recommendation for setting the timing with reference to the damper marks once he installs the Vacuum advance.
http://www.georgiajag.com/Documents/Vacuum Advance versus Vacuum Retard.htm
If you disable it as many of us do, the ignition timing will advance as much as 14* to 16* depending upon the module, which will put the spark somewhere within the BTDC marks on your damper...10 to 12* BTDC at idle with a disabled retard perhaps.
Rob @ BVU will give you his recommendation for setting the timing with reference to the damper marks once he installs the Vacuum advance.