first30k69hurstolds

I purchased NOS but without the box. I can see never used and in nice condition. $80 Nice piece to see correctly installed on a car.

stevengerard

good price if you ask me.

briane

I'd like to get this, PM sent.


Brian

70Post

Put me in line behind Brian.

Thanks and pm sent

first30k69hurstolds

Switch sold to Briane in combination with door panel reflectors. Thank you for all your interest.

firefrost gold

what was it for ??

first30k69hurstolds

Under hard acceleration it will adjust timing.

briane

A bit more explicitly, the Temperature Controlled Spark (TCS) system prevents vacuum advance under certain operating conditions. Working in conjunction with the transmission switch and the Temperature Vacuum Switch (TVS), if I recall correctly, the TCS solenoid closes off the distributor vacuum line in low gear if the engine is below or above certain temperature limits. I really need to refresh my memory on the conditions. But its an early emission control, generally removed or bypassed.

442Fred

Fisick repops them too in case you missed out on this one.

bwichman

Did all cars have them ? I just came from the Olds Nationals and noticed a few that had them, mine doesn't ( 1970 W30). What is needed to install ? or is it not that important to have.

briane

It is part of the emission control package, eliminating the vacuum to the distributor advance under certain conditions. Its not essential to be in place and most likely somewhat detrimental. The system was used with all '70 (and a variant in later years) engines including the L6. Chevrolet had a similar system but different in the interconnect details, as did Pontiac and Buick.


I'm more familiar with the Chevrolet system, having written an article about some years back. The Olds system is diagrammed in the Shop Manual on pages 6C-16 thru 6C19 and on page 6K-10. There seems to be a discrepancy as to when the Thermostatic Vacuum Switch is part of the system and when it is not. Not doubt more knowledgeable people here can shed light on this. According to page 6C-16 with a manual transmission, you only get vacuum advance in 4th gear.