Quick carb question...

[Moparlike]

Hey.
Can anyone please tell me if this should be plugged, or left open?
Thanks!!!

 

[72RoadrunnerGTX]

No functional evaporative recover system, the enclosed bowl vent nipple needs to be open.

 

[PurpleBeeper]

I agree, leave it open

 

[62MAX]

No functional evaporative recover system, the enclosed bowl vent nipple needs to be open.

Just depends !

 

[72RoadrunnerGTX]

The use of a ’70-71 E.C.S. 3-nipple breather would constitute a functional evaporative recovery system. Short of that, it was my understanding the OP's question was should it be plugged off or not.

 

[mopar 3 B]

Would it not also depend on states emissions laws? I don't think venting into the crank case would be a good idea.

 

[62MAX]

Then that would depend on the OP's system application

 

[72RoadrunnerGTX]

So then, just what OE “system application” calls for the enclosed bowl vent valve nipple to be plugged off?

Emissions laws? On a 50-year car? California maybe. Even if so, that would require maintaining emissions equipment originally installed based on date of manufacture. From the OP’s avatar, it appears we are talking about a ’69, bowl vents valves were open in that year.

“venting into the crankcase”, for ’70 & 71 E.C.S., good idea or not, that’s how it was designed. The crankcase was used to store evaporative emissions from both the bowl vent valve and fuel tank, to be consumed through the PCV when running.

 

[62MAX]

Some very early A12 cars had no bowl vent and the OP's bowl in question is 70 and later .

 

[72RoadrunnerGTX]

The hex head bowl screws indicate a re-issue, likely a 4670 re-issue. The re-issues all came with the later enclosed blow vent valve float bowl. Avatar again indicates a ’69 Road Runner as the application here. Used on a vehicle without an evaporative recover system of some kind, it should be left open to function as it was designed for a street driven car.

 

[70sixpkrt]

Some very early A12 cars had no bowl vent and the OP's bowl in question is 70 and later .

Just like these:

 

[72RoadrunnerGTX]

I see an open bowl vent valve on that center carb, pre-enclosed bowl vent valve version. Never seen an OE Holley without one or the other. Plenty of aftermarket Holley’s don’t have bowl vent valves.

 

[70sixpkrt]

Open bowl vent valve yes but no bowl vent.

 

[72RoadrunnerGTX]

Curious, just what bowl vent or vents are not present in that picture? I see three main bowl vents on three carbs, and an open idle bowl vent valve on the center carb.

 

[70sixpkrt]

The OP picture is a bowl vent.

 

[70sixpkrt]

No bowl vent.

 

[70sixpkrt]

I should have clarified no float bowl vent "nipple".

 

[72RoadrunnerGTX]

You are pointing out the hose nipple for the enclosed idle bowl vent valve for ’70 ECS and ’71 and up federal production. Yes, prior to ’70 and federal ’70 production, the center carb ran an open idle bowl vent valve, by definition, would not have a need for a hose nipple. The bowl venting is the same.

 

[67 coronet]

short answer is leave it open. if you are worried about any junk getting in there, then put a cheep paper element fuel filter on it. it will act like an air filter for it.