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Bowl Vent Adjustment
https://www.slantsix.org/forum/viewtopic.php?t=21902		 Page 1 of 1
Author:  ESP47 [ Fri Feb 16, 2007 12:40 pm ]
Post subject:  Bowl Vent Adjustment
Ok im in sort of an uphill battle here with a crappy remanufactured 1920 Holley and a Haynes manual. But they're all I have for now so bear with me.

This is what the Haynes manual says

With the throttle valve plate closed to its idling speed position, it should be possible to insert a 3/32 in diameter twist drill between the fuel bowl vent and its seat. Any adjustment should be carried out by carefully bending the vent valve rod at its horizontal section.

Ok first of all, what exactly is a twist drill? And is it even necessary to carry out this measurement with one? Right now on my carb, the valve rod seems to always be pushing down on the seat. When I hit the gas it pushes it down even more. My question is, should the rod be just barely resting on top of the seat at normal idle or should it always be pushing down on it a little bit? Thanks
Author:  icaneat50eggs [ Fri Feb 16, 2007 12:48 pm ]
Post subject: 
Just a regular drill bit. They are telling you to use it as a gauge, too hard to measure otherwise.
Author:  AnotherSix [ Fri Feb 16, 2007 12:50 pm ]
Post subject: 
I'm not clear on the rod this or that. However, a twist drill is just a drill bit. The vent adjustment in simple terms: When the throttle is at normal warm idle, the vent should be open 3/32" or whatever the spec is. It should close when you apply throttle. They are just telling you to stick a drill in there as a gauge to measure the opening.
Author:  SlantSixDan [ Fri Feb 16, 2007 1:57 pm ]
Post subject:  Re: Bowl Vent Adjustment
Quote:
Ok im in sort of an uphill battle here with a crappy remanufactured 1920 Holley and a Haynes manual.
Oof. Those two items practically guarantee unsatisfactory results. You really need to buy at least the FSM, preferably together with the other books mentioned in this post.
Quote:
With the throttle valve plate closed to its idling speed position, it should be possible to insert a 3/32 in diameter twist drill between the fuel bowl vent and its seat. Any adjustment should be carried out by carefully bending the vent valve rod at its horizontal section.

Ok first of all, what exactly is a twist drill?
A drill bit.
Quote:
And is it even necessary to carry out this measurement with one?
No, you can use any rod that's 3/32" diameter. It just happens that most of us have easier access to a 3/32" drill bit than to any other 3/32" diameter rod.
Quote:
Right now on my carb, the valve rod seems to always be pushing down on the seat. When I hit the gas it pushes it down even more. My question is, should the rod be just barely resting on top of the seat at normal idle or should it always be pushing down on it a little bit?
Neither. Once you've set the engine idle speed correctly (between 600 and 750 rpm or so, depending on your model, year, transmission and emissions package), with the throttle all the way closed to the idle position, there needs to be the specified 3/32" clearance. If there is not, the bowl vent will not open at idle, causing problems with driveability, idling and mileage.
Author:  ESP47 [ Fri Feb 16, 2007 10:43 pm ]
Post subject: 
Thanks for all the tips guys. I bought two of those books in that other thread but have yet to find a Factory Service Manual at a resaonable price.

Dan, im confused on to where im actually measuring it from. Actually im confused on what the terms are as well. Should the rod be 3/32" above the actual little valve it pushes down, or 3/32" above the ring deal that is flush with the carb (seat?)?

So the rod shouldnt be touching at all when at idle and only when applying throttle, correct? Sorry for the dumb questions, im still learning here.
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