TH350 modulator vacuum line
 

Discovered today my 1970 C10 doesnt have a vacuum line to the modulator

Am I ok to hook up a rubber line and where does it come from? carb, manifold?

Thanks guys

Re: TH350 modulator vacuum line
 

Manifold vacuum.

Ideally you want a hard line using short pieces of vacuum hose at both ends to connect to vac source on manifold and Vac modulator. All rubber line can kink and or collapse under vacuum.

You can buy straight hard line and use a simple hand held tube bender like one from Harbor Freight. Use a coat hanger as a template then just bend up the hard line.

Re: TH350 modulator vacuum line
 

ok great thanks, I'll have a hunt about on the manifold and see if I can find a vacuum outlet.

Could I just use hard brake line do you think?

Thanks

Re: TH350 modulator vacuum line
 

the smaller size hard brake line (1/8" ID) would be fine. If you don't have a current unused vac port you can put a T adapter on the one the power brake booster uses with a reducer on one side for the smaller vac line of trans vac modulator

You can sip tie the hard line to trans dip stick tube and some place on side of trans near vac mod. IIRC the factory one had a tab that used one of the bellhousing bolt holes. Just something to keep it from moving around as it otherwise has no stress on it

while not my C10, my 67 Camaro with TH350 I use this vac port from manifold. The T fitting is a stock Camaro part and I have seen them FS form either Classic Industries or Heartbeat City. Otherwise just buy some NPT fittings to make what you need

Re: TH350 modulator vacuum line
 

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Re: TH350 modulator vacuum line
 

Maybe Inline Tube or some other vendor makes a tube with the tab on it that goes to a trans bell housing bolt to stabilize it?