Topic: Welch plug

[AlekStooge]

These are PD46C carbs. Looks like there supposed to be a welch plug here on the end of the fuel rail line. This is carb 1.

Although everytime I look on ebay at carb bodies for sale they don't have a welch plug here but they do for the other two ports the throttle and choke shafts ends?

Does anyone here make welch plugs if needed?

[madmtnmotors]

Not needed since the hole does not go all the way through. Many other PD carbs are the same. If needed you would know immediately since fuel would leak profusely from here until your tank was empty.   

[AlekStooge]

Good that's what I was hoping to avoid. It looked like it went through. Any idea why it's there? I know some of the other PD carbs have an accelerator pump. Just curious.

[TwoTired]

The carb castings are the same for each position.  But, they are drilled uniquely for each position.  You only need Welch plugs to seal up the drill passages that you don't want leaking.   

I think the 550 is the only PD set that doesn't have accelerator pumps.  They could though, I believe the castings properly cast to allow drilling for it.  Never known it to be done though.  Really only needed if you insist on whacking the throttle wide open from low RPM.  550 owners are smarter than to do that. :-)

[AlekStooge]

You are correct. They definitley don't have accelerator pumps. What purpose do accelerator pumps serve?

Thanks for your help guys.

[Deltarider]

[...]What purpose do accelerator pumps serve?

These jets squirt a little extra fuel in the carbs when you open the throttle to accelerate. They react to a change in the underpressure.