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1928 standard vacuum fuel system diagnosis (follow up)


michealbernal

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Herbert 25-25

I was able to get back to my vacuum fuel system today.  I found that the small chip on  the inner tank flapper valve did not effect its sealing capabilities as it was outside the sealing surface.  I performed the water and suction tests on it and it held fine.  I then disassembled the vacuum inlet portion of the tank top.  I noticed that my vacuum inlet did not match the photos  provided.  There seems to be a part missing.  In the photos there is a small cup shaped metal disk with a hole in the center just under where the vacuum line attached to the top of the tank.  I did not find that disk in my tank.  My tank is a model "N".  Did they all take this disk.  It appears to be an upper seat for the vacuum valve maybe.  Any info. appreciated.  Thanks.  Mike

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Michael, 

    I wonder if your tubing is on the correct threaded hole in the top.  

The atmospheric vent is the threaded fitting closest to the edge.  This has the brass ring under the threaded connection to provide a seat for the vent pipe.  This valve is like a car valve.  It seats in the down stroke.

The vacuum fitting is closer in to the center of the top.  It has a needle and seat like a carburetor.  It seals on the up stroke of the needle.  There is no ring under the threaded connection on the top.  This is the threaded connection closest to the lid center is the one that connects to the intake manifold.     Hugh

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One more item.  The lid only goes on one way - unless it has been put on incorrectly.  The vent valve has a hole further out in the bolt pattern.  There are 8 bolts, but 9 holes in the bolt circle.  There is one hole between the holes on the lid and the tank and the gasket.  The extra holes all need to match up when assembled.

Hugh

 

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Herbert 25-25

I am full of blue mud clear  up to my ears.  That small cup shaped piece with the hole in the center goes under the atmospheric vent tub NOT as I wrote, under the vacuum line.  It is the part you labeled "vent(ring below) on the postitnote on the photo.  Anyway that ring is missing from my tank.  I would assume that is at least part of my problem.  Do you have any idea where I might be able to obtain one of these rings.  Thanks again  Mike

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Mike, 

     There are a lot of bad vacuum tanks out there.  The lid is pot metal.  I would expect there are rings available.  

Consider calling www.classicpreservation.com     518-374-5078   

I have one in another tank that I may be able to get out for dimensional purposes, but easier if you can find one from someone.

 

Also, test the 2 valves in the lid.  Use the vent tube in each connection.  Use teflon paste on the threads.  blow on or suck on the vent tube and see if the valves are seating.

Hugh

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Hugh, Thanks for all the help, I will give them a call.  I tried the testing the two valves by sucking and blowing on them and they are both holding.  I suspect that the missing ring has something to do with why my tank is not functioning correctly.  Thanks again.  Mike

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