edelbrock carb vac leak at choke

[40cpe]

Edelbrock 1406. Found this today while adjusting the carburetor. See the picture below. I have a vacuum leak on the choke housing at a hole just below the electric choke cover. I could plug it, but am uncertain if it is there for the choke function. Information on what to do with it is appreciated.

[craig]

The hole should have a metal tube coming out of it. A rubber hose would connect it to the tube at the top of the air horn. Yes it creates a vacuum bleed, to benefit the choke pull off

[craig]

I need to add to my previous post. Before this type of carb had an electric choke thermostat, the vacuum tube was connected to a hot air tube at the exhaust manifold' which would warm the thermostatic spring to open the choke. The only way the heat would get into the thermostat housing was from the vacuum at this outlet. The vacuum is manifold vacuum that has bled past the choke pull off piston in the choke housing. Now, some may argue this, but if you block off this vac passage, the choke pull off won't work like it should and the electric thermostat can actually over heat and burn out the heating element.
You will see this vacuum line on any universal type carb with an electric choke

[KULTULZ]

Originally Posted by 40cpe

Edelbrock 1406.

Found this today while adjusting the carburetor. See the picture below. I have a vacuum leak on the choke housing at a hole just below the electric choke cover. I could plug it, but am uncertain if it is there for the choke function. Information on what to do with it is appreciated.

Originally Posted by craig

The hole should have a metal tube coming out of it. A rubber hose would connect it to the tube at the top of the air horn. Yes it creates a vacuum bleed, to benefit the choke pull off

Originally Posted by craig

I need to add to my previous post. Before this type of carb had an electric choke thermostat, the vacuum tube was connected to a hot air tube at the exhaust manifold' which would warm the thermostatic spring to open the choke. The only way the heat would get into the thermostat housing was from the vacuum at this outlet. The vacuum is manifold vacuum that has bled past the choke pull off piston in the choke housing. Now, some may argue this, but if you block off this vac passage, the choke pull off won't work like it should and the electric thermostat can actually over heat and burn out the heating element.

You will see this vacuum line on any universal type carb with an electric choke

Interesting subject...

As Craig stated, that is the hot air source (not actual exhaust) for a hot air choke system. You or someone must have put an electric choke conversion kit on it.

It is debatable as to whether the electric choke cap must be ventilated as to keep it from overheating but HOLLEY does recommend cooling air on it's 12V conversions (full electric choke).

The trouble is that unfiltered outside air is being drawn into the choke/carb/engine presently.

As Craig has stated, the proper way to vent (IMO) is to insert a short piece of steel tubing into the inlet opening and run a rubber hose to the air-horn filtered (air cleaner element) fresh air inlet (if so equipped).

I have read over the -EDELBROCK CONVERSION INSTRUCTIONS- and see no reference to this.

Instruction Sheet Here- http://www.jegs.com/InstallationInst...0/350-1478.pdf

If you have a bad idle (too lean) with the additional air draw, you can re-tune the carb or call EDELEBROCK HOTLINE to see what their recommendation(s) are (as or eliminating/defeating the air draw).

[KULTULZ]

...sigh...

I have been consecrating on this and have come across this conclusion ...

An EDEL that comes through with MANUAL CHOKE has the vacuum source on the actual throttle body (under the choke housing) plugged. The conversion kit instructions has you remove this plug to provide manifold vacuum to the the choke housing asm. As there is no heated air draw (this provision must have not been carried over from the prior AFB on the EDEL re-design), there is no provision on the carb air-horn for filtered air ingestion and they obviously have no concern for drawing unfiltered out-side air. The design has to be for cooling of the electric choke cap only.

Also, the EDEL re-design made no allowance for the previous AFB hot air choke or hot air/electric assist choke. So, the EDELBROCK current design must be meant to allow the vacuum leak (actually source) to be open unfiltered.

Opinions?

[40cpe]

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Thank you, KULTULZ, for putting so much thought into this. I searched this topic and found one post that said the hole is an atmospheric vent for the choke pull-off. The pull-off is a piston in a bore, thus is not tightly sealed. The vacuum is what leaks by the piston. At any rate, I found many pictures of the choke portion of the carb and they were all open. What ever the function, I'll leave mine open.

[KULTULZ]

Originally Posted by 40cpe

Thank you, KULTULZ, for putting so much thought into this.

I searched this topic and found one post that said the hole is an atmospheric vent for the choke pull-off. The pull-off is a piston in a bore, thus is not tightly sealed. The vacuum is what leaks by the piston.

At any rate, I found many pictures of the choke portion of the carb and they were all open. What ever the function, I'll leave mine open.

No problem. I learned from this post also ...