70 LT-1 Vacuum Advance Solenoid

[Hotrodpaul]

Just found the correct hose routing in the Assy manual:

Manifold Vacuum - Metal hose barb to the right
Dist Vacuum Advance - Plastic barb @ 90 degrees to solenoid centerline
Carb Vent - Plastic Hose barb to the left, in line with soleniod axis.

This routing makes sense, based on my previous post. Looks like when the solenoid is energized, vacuum is blocked and engine is running without the additional timing. When voltage is removed, with the car in reverse or drive (majority of the time), vacuum is allowed to pass to the advance canister, adding timing to the engine.

I would assume this is done in reverse and drive to prevent the engine from dying. There is also a temp switch located in the head that must be wired in as well but I do not know its function. A little more research to go.

Paul
69 Camaro SS L78
70 Z28 LT1 M40

[Belair62]

The engine has to be at operating temp for the stuff to work as engineered..temp sender achieves that.

[YENKO DEUCE REGISTRY]

The last two posts got it right! The TCS prevents full vaccum advance until operating temp is reached 'and' high gear is achieved - regardless as to the trans type, and the 432 unit is the '70 small block item. The junk yards are full of them!