Vac Hose Location

[CAPNZ]

On my 73 LS4 there's a vacum advance, (at least that's what the Assembly Manual says but it's hard to see the hose locations). Can anyone help?
TIA
"Jeff"

 

[JohnZ]

That's the TCS (Transmission Controlled Spark) solenoid; it goes in the vacuum line between the carb and the distributor and either opens or closes the hose to the vacuum advance unit. That system denies vacuum to the distributor unless the car is in high gear, the engine hasn't warmed up yet, or the engine is overheating; it's controlled electrically by a switch on the transmission and a coolant temperature sensor. Most people just bypass it and run the vacuum line direct, and only connect it properly for judging.

 

[CAPNZ]

Thanks John, but there's two ports on it,one in the back and one in the front plus the electrical connector. Why does the Assembly manual show it as a vacum advance and it says LS4 only. Maybe just a bad picture???
Jeff

 

[JohnZ]

Is it a 4-speed or automatic? They used different solenoids - the 4-speed solenoid had two vacuum ports, and the automatic solenoid had three. The Assembly Manual will show you the correct installation.

 

[CAPNZ]

Mines an automatic, 2 hose connections.
TIA
"Jeff"