help needed with 351W 4v vacuum line; 1969 Mach 1

[the ponz 10]

I recently acquired a 1969 Mach 1. It was rebuilt in 2006 with a 351 Windsor, 4v, and a shaker hood. This morning, I removed the shaker and air filter assembly to clean up the engine bay. When I had finished, I noticed this vacuum line laying towards the rear of the engine. It is not the vacuum for the shaker. I’m nearly convinced that I accidently knocked it loose from somewhere without knowing that I had done so.

 

What is it; where does it go?

 

Thanks for the help.

 

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[LindenBruce 27]

Does your car have A/C? If so it may go to the vacuum canister under the passenger side hood hinge. You are positive it's not for the shaker? Bruce

[Phils69 27]

If you have an auto tranny it probaly goes to it. See if you see a tube coming from there not connected to anything

[miketyler 15]

Not sure on the 351w but wasn't there a bi-metal switch on bottom of the air cleaner that controlled vacuum to the snorkel air door for heated air?

[the ponz 10]

Thanks for the replies.

 

- I'm sure it's not for the shaker; that's accounted for.

- The line is not for the Auto Xmsn; that's accounted for.

- the air filter assembly was my first guess, but the can has no provision for a

vacuum line to attach.

- the car came from the factory with air, however, that was replaced with a

modern Classic Auto Air unit during the rebuild. I suspect it is the line to

the factory installed air conditioner vacuum canister, which has been

removed. If that is the case, I should probably remove the line and cap the

port.

 

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Any more thoughts???

[LoneWolf2U 136]

Does the new climate unit have cable controls?

If it is using the factory distribution unit, You need vac to make the doors work.

[the ponz 10]

The new ac unit does not use vacuum for anything. I have convinced myself that is left over from the original factory ac system. I removed the line and capped the port.

 

Thanks for the replies.

[miketyler 15]

Distributor modulator? (Distovac)

[Fordrevhead 29]

There is a boat load of vacuum lines for the factory ac (see line kit attached) but the onethat comes to mind is the one that goes to the vacuum servo that helps move the defroster door.

[miketyler 15]

maybe a vacuum controlled heater valve?

[69gmachine 15]

The vacuum line in the picture is too large to be the AC hot water valve control line. You should have a ported vacuum switch in the water inlet at the front of the intake. The line that provides vacuum to the switch has a red stripe (if original) and plugs into the bottom nipple at the switch and the fitting at the rear of the intake as in your picture. There should be another line from the carb to the switch with a yellow stripe (to top nipple), and one from the vacuum advance with a green stripe (middle nipple).

[the ponz 10]

maybe a vacuum controlled heater valve?

 

 

Yes sir, that is what I'm betting on.

 

The heater valve to the core is now cable controlled.

 

Thanks.

[the ponz 10]

I found an older photo of the engine bay before I bought the car. The vacuum line I was wondering about was in fact hooked to the shaker intake, (before I removed the shaker, and mistakenly hooked up to the wrong line). That means I have the wrong line presently hooked to the shaker. I will correct that tonight.

 

However, that now puts me back to wondering what the other line is for. Please look at the photo and reply with your wisdom. The rubber vacuum line attaches to a hard metal line and disappears down the passenger side of the engine. It may go to the transmission, however, there is a similar line going to the transmission on the drivers side of the engine, (as identified in the previously posted photo.

 

I just don't know.

 

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[69gmachine 15]

As long as the shaker is getting manifold vacuum, it's not the "wrong" line. If you're trying to use the factory color coding, the line that goes to the shaker is supposed to have a blue stripe.

 

Look to see where the metal line that goes down the passenger side originates. My guess is that it's the hot air supply for the factory choke and is attached to the exhaust manifold.

[the ponz 10]

As long as the shaker is getting manifold vacuum, it's not the "wrong" line. If you're trying to use the factory color coding, the line that goes to the shaker is supposed to have a blue stripe.

 

Look to see where the metal line that goes down the passenger side originates. My guess is that it's the hot air supply for the factory choke and is attached to the exhaust manifold.

 

Great suggestion. Thank you.

 

I have noticed that when starting the engine when it is cold, the idle is not elevated like it should be. I must have knocked it off the exhaust manifold while cleaning the engine bay.

[the ponz 10]

The engine had an new Edelbrock carb installed on it in 2006 or so. I'm not sure which model it is.

 

I believe it has a modern electronic choke control on it. If it does, would the vacuum line going to the exhaust manifold need to be hooked to a vacuum source, or can I cap it off?