What is this carb inlet?

[flatiron14]

Instead of rebuilding the old one, which had some wear and the bowls were kinda gunky, I decided to replace my Edelbrock 1409 carb on my '92 Merc 305. Everything seems to line up and function fine, however, when I got the motor running, I could hear a hissing and found this hole in the front of the carb that was drawing a lot of air. I looked in the manual and found this is the PCV valve inlet on some carbs? Is it supposed to be drilled in my marine carb? Also, when I plug this hole with my finger it brings the rpms down and at idle it can stall the motor. What do I need to do here?

I attatched an image of where this inlet is on my carb.

 

[picklenjim]

Re: What is this carb inlet?

Plug it up and set your idle where it needs to be.

 

[jerryjerry05]

Re: What is this carb inlet?

Crank case ventilation port or PVC port. You can put a plug in it.J

 

[Bondo]

Re: What is this carb inlet?

Ayuh,.... Hook up a Vacuum Gauge to it,... You'll be a step ahead of everybodyelse...

 

[Maclin]

Re: What is this carb inlet?

Plug it up, the mix will be WAY too lean at any RPM if that is open.

In NHRA dragracing some classes have to use the stock carb so they leave that open and jet up 3 or 4 steps, gives them more cfm than stock. I only typed that in to give an example of how much too lean it will be if that is left open.

Plug it with a plug, plug it with a gauge, but Plug it!

 

[SuperNova]

Re: What is this carb inlet?

I looked in the manual and found this is the PCV valve inlet on some carbs? Is it supposed to be drilled in my marine carb?
I attatched an image of where this inlet is on my carb.

No, I don't think that should be drilled through. I ran the same carb on one of my boats and I know it wasn't drilled on that one. 'Course, maybe mine was the one screwed up.

 

[FreeBeeTony]

Re: What is this carb inlet?

I am also running that carb......not sure if it's drilled through though.


I doubt it is because I used a vacumm gauge when adjusting the carb and I know my readings were ~19 or so.........think they would be lower if it was drilled through.

 

[zbnutcase]

Re: What is this carb inlet?

I have yet to see one drilled on a 1409, but maybe they are now since the OEMs are starting to use PCV valves. 'nutcase

 

[Silvertip]

Re: What is this carb inlet?

Plug it up. Then readjust the idle mixture screws on either side of that hole. Then set the idle speed and go boating. Take frequent plug readings to ensure you have the jetting proper.

 

[FreeBeeTony]

Re: What is this carb inlet?

If you go to the Edelbrock website, and look at the pic of the 1409......it shows the hole covered.

 

[flatiron14]

Re: What is this carb inlet?

Thanks so much for the info! I'll plug it up and set my idle and see how she runs.

 

[Maclin]

Re: What is this carb inlet?

Automotive stores will have a vacuum port plug kit, usually an assorment and one or more of those will be the size you need. I know when buying new Holleys and Carters (back in THAT day) they came with some plugs in a baggy in with the carb.