Re-routing TH350 Vacuum Modulator Vacuum Line...What Size Vacuum Hose ?

[Tynan918]

I'm re-routing my vacuum modulator vacuum lines because it was 3 way routed into the vacuum canister ball on the passenger side of the engine and then to the full vacuum port on the carburetor...

I'm told this is wrong and my transmission vacuum modulator isn't getting the full vacuum requirement being routed like this. I was told to get an intake manifold tee fitting and run the vacuum modulator straight to the T fitting on the intake manifold to provide the full manifold vacuum required for the modulator.

I bought this intake manifold tee fitting, one end is 3/8 for my brake booster and the other end is 1/4 for my transmission vacuum modulator.

I also bought 10' of 1/4 vacuum hose, but after removing the old hoses I see the hose size is 3/16...

Can I still use the 1/4 hose on the vacuum modulator or will I need a reducer fitting at the vacuum modulator to make it fit the vacuum modulator nipple ?

 

[mikester]

I dont remember the size of the hose going to the modulator. Its been a while but I can probably let you know tomorrow. A few things though. The fitting on the manifold will feed the modulator and the vacuum ball at the same time with a plastic T fitting inline. The larger nipple on the fitting should go to the booster.
In the video I see a PCV valve. What is that hooked to ? And why do you have a vacuum gauge ? The other thing I noticed. It looks like you have something going on with the vacuum line to the distributor. Whats that about ? You also need to make sure the line going to the modulator will be away from the header and exhaust.

 

[Tynan918]

The fitting on the manifold will feed the modulator and the vacuum ball at the same time with a plastic T fitting inline.

What is the ball used for ? I'm told to eliminate it because I don't have AC...

In the video I see a PCV valve. What is that hooked to ?

PCV is hooked to the back of the carburetor.

And why do you have a vacuum gauge ?

Adjusting my vacuum advance canister.

The other thing I noticed. It looks like you have something going on with the vacuum line to the distributor.

Disconnected and plugged it off to set base timing and adjust the vacuum advance canister.

 

[airboatgreg]

3?16 to 1/4" Run it off the tee from the intake manifold or rear of carb. The vacuum ball is a reservoir to allow the heater to move doors to defrost

 

[Tynan918]

The vacuum ball is a reservoir to allow the heater to move doors to defrost

So really not needed in the summer time ?

 

[DRIVEN]

It's there for a reason.