| Re: [GMCnet] Ford A426C brake vacuum pump, your opinion please? [message #327603 is a reply to message #327596] |
Sat, 30 December 2017 14:44  |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Bruce,
Dave L's configuration:
Booster port #1 - check valve #1 - Ford Azure / F-150 vacuum pump
Booster port #2 - check valve #2 - Engine
Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808
-----Original Message-----
From: Gmclist [mailto:gmclist-bounces@list.gmcnet.org] On Behalf Of Bruce Hislop
Sent: Sunday, December 31, 2017 1:21 AM
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] Ford A426C brake vacuum pump, your opinion please?
Just my farm-boy mechanic thoughts on vacuum pumps and reservoirs.
In my opinion, both are a great idea. I do have an opinion (or idea) on how they should be plumbed and why. The engine has a huge
capacity to draw down vacuum (hoping that is proper terminology), as compared to an electric pump. I currently have a JC4 pump which
is plumbed in series between the vacuum booster and the engine, in other words the engine vacuum flows through the pump. My idea is
the system should be plumbed in the following order.
Vacuum booster ->check valve --> vacuum pump ---> vacuum reservoir ->check valve ---> engine.
My reasoning is the engine's vacuum capacity will draw down the reservoir and booster almost immediately and the check valves will
keep the system at maximum vacuum (or minimum depending on your point of view). If the engine quits, and say you were going down a
hill which required multiple brake applications, the vacuum reservoir would provide a source of vacuum for a short while. Once the
reservoir vacuum went below the pump setting, then the pump would start.
Now this is point where my configuration come into play. With the pump in-line right at the booster, there is only the booster
reservoir to pump down, so the pump should be able to do that fairly quickly to regain power in the brakes. If the pump had to draw
down the reservoir as well, it would take much longer to do so and in the meantime your booster brake assist would be very poor.
Does this make sense? I haven't seen where this has been written-up in the past. Or maybe my assumptions are all wrong here.
Comments or ideas?
Thanks
--
Bruce Hislop
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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