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AutoVac size and type
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Author:  PeterJeffery [ Sun Dec 07, 2014 7:09 pm ]
Post subject:  AutoVac size and type

Hi All,
following the very helpful discussion of a serious carb leak on my newly acquired 1929 Desoto Roadster, I got it running nicely by fitting a pressure regulator between the SU pressure pump and carb. However, Steve rightly warned me that this could well be dangerous. As Tim suggested I have been since looking for an AutoVac (i.e. The gas pump) to get the car back to near original and just found one in the UK measuring 3 and half by 7 inches. Would this be the correct size? It would be good to know before I take a chance on it.
I am not sure whether all Desotos of this year were fitted with this form of gas pump or just the ones like mine made in Canada for export to New Zealand.

Many thanks and Happy Christmas and Motoring to all in the Club.


Author:  TimMabry [ Fri Dec 12, 2014 2:53 pm ]
Post subject:  Re: AutoVac size and type

It's a bit on the small size but should work. I measured the S-W unit on a 1925 Hudson 6 cylinder and it measures 10.25 x 4.50. Is it rebuilt? That alone could cost $300.
Not having a 29 parts book I can't say what was used originally, especially since it was an export. Are you concerned with originality? If so I'd do research (parts book, 29 experts) and buy the proper one. If that's not a concern Stewart-Warner units are far more common and easier to find rebuild parts followed by Autovac then Kingston. My guess is it originally had a Kingston. They can be found on the AACA forum.

I'm not a big fan of using copper for fuel line so my may want to switch that out for safety sake if that's what's on the car now.. Copper can crack from vibration.

Once you get a functional vacuum tank on the car I think you'll be pleased. You may have to prime it if the car sits for a long period but shutting off the fuel valve will limit that problem.

Author:  PeterJeffery [ Thu Jan 22, 2015 1:04 pm ]
Post subject:  Re: AutoVac size and type

Many belated thanks Tim. I will keep looking for one about the bigger size you have mentioned. In the meantime I will keep going with the regulated SU pressure pump. So far it all seems OK but will carry a fire extinguisher just in case! Peter

Author:  PeterJeffery [ Sat Jul 16, 2016 6:49 pm ]
Post subject:  Re: AutoVac size and type

Hi All (those who kindly advised me re an AutoVac),
I have now managed to find at auction an English Stockport AutoVac....actually I purchased all 3 of differing sizes for £100. All were in need of recommissioning and with the emailed help of Mr Martin Hull who is the only person I know in the UK who specialises in Autovacs I have restored one of the right capacity, taken off the wrong SU pressure pump and refitted an AutoVac to the car.....and it appears to work!
The Stromberg carb still drips when the choke is pulled fully out at start up but not when the car is running and the choke is in. I will give more details if interested and once I have run the car for a while.......just a little problem with a sticking clutch plate now! Many thanks for your helpful comments.
All the best and happy motoring.

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