Found random bolt by my carb.

[Homejville]

I was working on my carb the other day and found a metal plug. Not an electrical plug, a bolt plug. Its about 3/8 with a square head. I've seen someone else find it on their truck but never did say where it went. Plz help.its a 305 in a 1985 c10

 

[chengny]

Do you have manual brakes and a Rochester carburetor? I am no carb expert by any means, but the only port drilled/threaded for an NPT pipe plug - that I know of - is for the supply to the power brake vacuum assist booster. Like this:

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[Homejville]

It has power brakes w booster. I look where this plug was supposed to be but theres a metal line that goes to the brake booster

 

[chengny]

Okay so that port is being used for the power brake booster - and it is not the one shown above.

Big question is:

Where is the plug - the one that you are referring to - located?
Do you have a camera? A photo would help a lot.

 

[Homejville]

Okay so that port is being used for the power brake booster - and it is not the one shown above.

Big question is:

Where is the plug - the one that you are referring to - located?
Do you have a camera? A photo would help a lot.

No i do not have a camera at the moment. But the plug was just laying on the intake, between the valve covers.

 

[chengny]

You're talking about just a stray loose pipe plug you found laying on the intake manifold? Jeez dude - don't stress about that.

God only knows where it came from or why it was there. I certainly wouldn't loose any sleep over it - and it has nothing to do with the carburetor.

Here are are couple of images showing a SBC intake with what appear to be a couple of original plugs still in place:

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The hole with the plug in the back (near the distributor bore) is used to supply vacuum to things like the (automatic) transmission modulator & A/C operating controls.

The other plug - next to the thermostat landing area - is commonly used to allow a TVS (thermo vacuum switch) to be threaded in to manifold where it is in contact with engine coolant.

If one of these holes now has something screwed into it...that's probably where the mystery plug used to live.

 

[Homejville]

Well its a 4 barrel so I'm safe there. Thanks for all the help. The plug was rusty so its been there a while.

 

[chengny]

Whew! Thank God.