Petcock Replacement Smoothbores

[thewiz]

I have read through the searched forums about routing the vacuum hoses on stock carbs but I have a question on 33 smoothbores.

I ordered an OEM replacement that has the fuel line and vacuum line outlet. However the petcock I am removing (unknown type) does not have a vacuum line outlet.

So my question to the gurus is a)just cap the new petcock vacuum outlet or b) should the original setup have had some type of vacuum line running to it and I would have to run it on the new one.

Thanks for your help. John

[Billy Ricks]

I have read through the searched forums about routing the vacuum hoses on stock carbs but I have a question on 33 smoothbores.

I ordered an OEM replacement that has the fuel line and vacuum line outlet. However the petcock I am removing (unknown type) does not have a vacuum line outlet.

So my question to the gurus is a)just cap the new petcock vacuum outlet or b) should the original setup have had some type of vacuum line running to it and I would have to run it on the new one.

Thanks for your help. John

You're going to need a vacuum source to open the petcock or run it on prime and not forget to put it back on run.

[thewiz]

Thanks Billy,

So I guess what you are saying is that since the old petcock didn't have a prime setting, the vacuum outlet on the intake side between 2 and 3 was probably capped off (haven't pulled the tank all the way off to look yet but see no unattended hose there). That makes it a little clearer to me. So I will uncap and run a hose to the petcock.

[Billy Ricks]

Thanks Billy,

So I guess what you are saying is that since the old petcock didn't have a prime setting, the vacuum outlet on the intake side between 2 and 3 was probably capped off (haven't pulled the tank all the way off to look yet but see no unattended hose there). That makes it a little clearer to me. So I will uncap and run a hose to the petcock.

The outlet shouldn't be between the carbs, it should be right on top of carb #2. The outlet between the carbs should be a vent. You could use one of the synch ports for a vacuum source.