Dick Nyquist said.....
Date: Wed, 28 Dec 1994 09:24:36 -0800 (PST)
From: Dick Nyquist <dickn@hpspdbc.vid.hp.com>
Subject: vacuum
Not only have I driven Chevys with vacuum shifters (bad) but I still own an
antique bus with vacuum assisted mechanical brakes (very good).
As to wipers the only vacuum wipers I ever found to always work well were in my
'57 English Ford Console. It had a large vacuum reservoir with a check valve,
so the wipers would work even when you were passing a car in the rain.
( I was a teenager in those days and passed a lot of cars in the rain.)
Dick N
--- clip here ---
In addition to the aging and cracking of rubber hoses, another problem with
vacuum wipers was that the mechanism would "gum up" internally with age
slowing the wiper action even when going along a level stretch of road.
Once this happened, almost any acceleration effort would stop the wiper
action. The double-action fuel pump etc. couldn't overcome this problem.
I have a'53 Nash, among other cars, that is equipped with vacuum wipers and
they work fine even without the double-action fuel pump. (I can stop them
with hard acceleration, however.) The double-action pump, by the way, was
considered an "extra" available at additional cost! Being a tightwad by
nature, I never got round to buying this luxury and now it is a bit late to
go looking up a dealer.
The vacuum fuel tank, I think, has had a rough go in the press. Actually,
I've found them to be quite reliable and trouble free if one is willing to
exercise a little care along the way. They were usually mounted under the
bonnet on the bulkhead and looked like a juice can painted black with some
tubes soldered in the top. They had a float chamber much like that in a
carburetor. Manifold vacuum was carried through a rubber tube (would get
hard and crack due to the engine heat) to the tank. The vacuum tank had a
line connecting it to the fuel storage tank at the read of the car. Petrol
was "sucked" up from the storage tank into the vacuum tank. Once the
vacuum tank fuel level pushed up on the float to a predetermined point, a
valve closed shutting off the supply. The fuel in the vacuum tank was then
delivered to the carburetor by gravity as needed. Once the vacuum tank
fuel supply was lowered to a predetermined level, the valve opened and more
fuel arrived from the storage tank.
In addition to failed rubber lines, internal rust was a problem. In "the
old days" petrol was not as well refined as it is today. You may have paid
only 12 to 25 cents for a gallon of fuel back then, but you almost
certainly received dirt and water as well.
It can be successfully argued that storing even a small amount of petrol
under the bonnet can be quite dangerous - and was. But the operation of
the system proved to be quite successful on many vehicles for many years.
I find it simple to keep old crocks operating with their originally
equipped vacuum tanks quietly doing their job. Do check those rubber lines
each season before setting out on a motor trip, however.
Dick
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