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help me with vacuum port on intake manifold

  
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help me with vacuum port on intake manifold

 
sick66one sick66one
New User | Posts: 2 | Joined: 04/14
Posted: 04/15/14
10:15 PM

I own a '68 firebird 350

I go to start her up after sitting for a while. It takes a moment but when she fires up, I hear a small pop and *hiss* I'm late for work so I lock her up and look at it the next day. I open the hood, start her up and find an open vacuum port on the intake manifold that is sucking air. I figure a hose must have came off, but upon my inspection I find no disconnected hoses. My question, is it suppose to be capped off? Or do I need to take a better look cause a hose absolutely connects to it?

I am ashamed, I should know my engine better than this.

2014 04 15 211901 Zpsf28c6211  

M-22 M-22
New User | Posts: 8 | Joined: 08/13
Posted: 04/16/14
03:14 AM

That looks like the PCV port where the hose from the valley pan would hook up to. But I see that it's run to the front of the carb. so I imagine that they just had that port plugged. Now I'm going to have to go out and take a look at mine to remember. lol  

idrivejunk idrivejunk
Addict | Posts: 5138 | Joined: 12/09
Posted: 04/16/14
04:46 AM

Yep that needs to be plugged. Must have either had a cap over it that finally got so soft that the engine sucked it in and ate it, or maybe it had a backfire while starting and blew the cap off. You might look around under the car for it. Those caps sure don't last very long.  
idrivejunk

Pontiacman8 Pontiacman8
Moderator | Posts: 5775 | Joined: 02/08
Posted: 04/16/14
03:10 PM

If it is a screw in type unscrew it and get a screw in plug that way you will not have to keep replacing vacuum caps.  
Engine builder,self taught auto body guy.
Horsepower sells engines and torque wins races

Pontiacman8
Pontiacman8
Pontiacman8

sick66one sick66one
New User | Posts: 2 | Joined: 04/14
Posted: 04/16/14
07:55 PM

Thanks for the responses guys. I will get her plugged up right away, I will make sure to check if its threaded, it would be nice to have a more permanent solution.  

shyrgfuh3 shyrgfuh3
Enthusiast | Posts: 447 | Joined: 11/13
Posted: 04/18/14
05:21 AM

why do you have 2 vacuum lines going to the front of your carb?

is the distributor vac going to ported or manifold vac?