1968 Not holding idle.. help identify this bolt?

[jamoaus]

Hi all

I came back to my 68 GTCS after storing her for a bit and she started up fine but then couldn’t hold idle. I finally got her moving by feathering the throttle and found this bolt underneath. Anyone know what this bolt does?

Appreciate the help in identifying where this goes..

Thanks
J

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[cmacias24]

That looks like an oil pan drain plug. If it’s not holding idle, start by Loki g for an obvious vacuum leak.


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[Mosesatm]

Also check to see if there is any oil in the engine.

New gasoline evaporates more rapidly than the old stuff, and the residue left over can clog up the carburetors. You may want to try some running some injector cleaner through the gas tank.

Rob may have better ideas.

 

[jamoaus]

So I found the issue. For some reason that screw was plugging a hose that connected onto the back of the carb and under the filter. It wasn’t even a tight seal.

No idea what it was for.. looks like a dodgy fix by someone. I have to get my carb fixed or replaced anyways (carb is now leaking fuel on to the header)

Thanks for those that responded! Definitely appreciated the help and guidance

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[TraveledGTCS]

If I'm not mistaken, that is the spacer vent which goes to the PCV valve on the valve cover.

 

[robert campbell]

Wow! What some fun! You are correct that it is an oil plug. So leaking out of the carb could just be old gaskets. You do not have the correct PCV Spacer under your carb. The "plugged" vacuum port is for a PCV valve and will be ok if everything is correct and functioning properly.

My guess is a carb that sat dry for a few months and the gaskets are now leaking. Letting it sit with some fresh gas may cure it..... Doubtful.... Time for a carb rebuild and a thorough inspection/cleansing for your fuel system.

Rob

 

[jamoaus]

Wow! What some fun! You are correct that it is an oil plug. So leaking out of the carb could just be old gaskets. You do not have the correct PCV Spacer under your carb. The "plugged" vacuum port is for a PCV valve and will be ok if everything is correct and functioning properly.

My guess is a carb that sat dry for a few months and the gaskets are now leaking. Letting it sit with some fresh gas may cure it..... Doubtful.... Time for a carb rebuild and a thorough inspection/cleansing for your fuel system.

Rob

Thats some valuable information right there! Thank you!

Now that I’ve plugged it, the car is back to her usual self and running fine. Question though - would this do any damage to the vehicle just by plugging it? Where was it meant to go to?


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[jamoaus]

If I'm not mistaken, that is the spacer vent which goes to the PCV valve on the valve cover.

Thank you. I’m not sure if I have a pcv valve?


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[rvrtrash]

The PCV valve (Positive Crankcase Ventilation) goes in the center of the oil filler cap, front of the left side valve cover. It's purpose is to pull gas blow by from the crankcase and route it to the carburetor where it can be burned. Before PCV valves, the oil filter cap had an air filter of sorts built into it that vented the blow by gases to the atmosphere. Here's a couple of pics, of a filler cap with a PCV valve and a vented filler cap.

Steve

 

[robert campbell]

So I found the issue. For some reason that screw was plugging a hose that connected onto the back of the carb and under the filter. It wasn’t even a tight seal.

No idea what it was for.. looks like a dodgy fix by someone. I have to get my carb fixed or replaced anyways (carb is now leaking fuel on to the header)

Thanks for those that responded! Definitely appreciated the help and guidance

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In this picture you can see the "passenger side" large port for a PCV valve. This port is common to the newer Holley carbs which one is on this car. More than likely this hose goes to PCV valve and the one in the spacer can be plugged.

No it will not hurt the car to have it plugged.

Rob

 

[jamoaus]

In this picture you can see the "passenger side" large port for a PCV valve. This port is common to the newer Holley carbs which one is on this car. More than likely this hose goes to PCV valve and the one in the spacer can be plugged.

No it will not hurt the car to have it plugged.

Rob

Thank you for the information [mention]robert campbell [/mention] appreciate the info. Yeah you’re right the pcv valve goes to the right on the passenger side.


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[robert campbell]

Your throttle return spring clip on the driver back carb stud is turned a bit. Can you show us a picture of your return spring set up?

Rob

 

[jamoaus]

Your throttle return spring clip on the driver back carb stud is turned a bit. Can you show us a picture of your return spring set up?

Rob

Does this help?

I’ve decided that the carb needs an overhaul anyway so I’m going to get that done asap. Can’t drive it all that much as I’m leaking gas from the diaphragm down onto the engine block. Not good.


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