What is it????
Le Mans Master
Joined: Sep 2000
Posts: 5,635
Likes: 4
From: Orlando Floriduh
Re: What is it???? (l2vette)
It was used in the very early 70's to allow spark advance in 1st and 2nd gears only by controling a vacuum switch that fed the vacuum advance unit.. I may be wrong about which gears but that's the basic concept.....
Le Mans Master
Joined: Sep 2000
Posts: 5,635
Likes: 4
From: Orlando Floriduh
Re: What is it???? (l2vette)
I do not have a factory manual for 72 but....According to a Haines manual (UGH) it was used in 1972. The switch was known as TCS. (transmission controlled spark)
Melting Slicks
Joined: Dec 2000
Posts: 3,407
Likes: 2
From: Carmichael CA
Re: What is it???? (l2vette)
The TCS for the Muncie 4 speed works the same as all the other TCS systems. When the engine is cold the temperature switch controls the vacuum solenoid and vacuum signal;thus vacuum advance is always closed off cause a cold engine does not like any extra advance. When the engine warms up then vacuum is allowed to flow at all times except for when the tranny switch controls the vacuum solenoid and in top gear (4th for the muncie 4 speed) the vacuum gets closed off so that the extra advance is not present while cruising; thus, saving gas and helping to keep the engine cooler.
The switch is mounted on the 3/4 shift lever on the tranny side case, and effectively grounds the lead when the tranny is shifted into 4th gear. If you still want to accelerate when in 4th (like racing) then you need to disconnect the switch so that you still get the power from extra ignition advance.
The switch is mounted on the 3/4 shift lever on the tranny side case, and effectively grounds the lead when the tranny is shifted into 4th gear. If you still want to accelerate when in 4th (like racing) then you need to disconnect the switch so that you still get the power from extra ignition advance.
