Joined: Jun 27, 2011 Posts: 262 Location: "Thumb" of Michigan
Posted: Fri Feb 03, 2012 2:51 pm Post subject: Dual AC Fuel pump connections
Another newbie question.
I'm installing a civvy (AC 9562) dual action fuel / vacuum pump on my F head engine - replacing a single action unit. Am I correct that the inlet (suction) portion of the pump is connected to the nipple on the intake manifold and the output (pressure) used to run the wipers?
I yes, does the application of vacuum at this point result in any performance. Changes in the engine itself? I'm currently running a Solex carb if that makes any difference.
Thanks!
Tim _________________ Tim Juhl
1952 M38A1
1946 Aeronca L16A Army Liaison Aircraft
Try to start with the intake manifold in your head. It sucks (unless the engine is supercharged). Now drop the word pressure from your vocabulary. Connect the manifold suck port to the out port (Blow port or exhaust port) of the vac pump. Connect the vac pump's suck port (IN port) to the line that goes to the vacuum wiper "T".
The engine was designed with this calibrated leak in the manifold. Thus the carb will need to be enrichened a bit. Usually a modest increase in idle mixture is all that is needed.
I assume from the discussion on the G503 board you know the 1/8" spacer goes with the civvy dual action pump? _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Joined: Jun 27, 2011 Posts: 262 Location: "Thumb" of Michigan
Posted: Fri Feb 03, 2012 8:38 pm Post subject: AC Pump
Yessir.... I know that 1/8th inch is correct for this pump.
As to the plumbing considerations - I was confused by a thread on a non-jeep discussion group discussing the installation of such a pump. What you say makes sense. However, adding to confusion was a series of posts I read on this site discussing teeing off the line from the pump and tying into a hole in the manifold near the carb.....something related to positive crankcase ventilation.
If I understand you correctly, I should be fine if I simply tie the positive pressure side of the pump to the manifold fitting and adjust the carb accordingly.
On a related topic, when I try to move the actuating arm on the pump by hand, it is extremely stiff. Is it supposed to be that way? When I opened it up it doesn't appear that it has been used since it was remanufactured and it moves freely when the big spring is removed.
That's again!
Tim _________________ Tim Juhl
1952 M38A1
1946 Aeronca L16A Army Liaison Aircraft
If I understand you correctly, I should be fine if I simply tie the positive pressure side of the pump to the manifold fitting and adjust the carb accordingly.
I can't agree or disagree with your assumption until you tell me which side of the pump [ out port (Blow port or exhaust port) ] or [ suck port (IN port) ]
you are calling
Joined: Jun 27, 2011 Posts: 262 Location: "Thumb" of Michigan
Posted: Sat Feb 04, 2012 7:00 pm Post subject: AC Pump
Suck? Blow? Am I in danger of violating forum rules?
My understanding is you apply vacuum (suck) to the wipers and pressure (blow) to the manifold fitting. "Positive pressure" would be the "blow" side of the pump.
I'm an old science teacher and we used to use the term "negative pressure" for vacuum and "positive pressure" for pressure. Sorry if I wasn't too clear.
Tim _________________ Tim Juhl
1952 M38A1
1946 Aeronca L16A Army Liaison Aircraft
You were clear. It was the lack of a common set of communication terms that caused the confusion. When I set up the port nomenclatures I assumed you would follow up with the same nomenclatures in your reply. In mechanical things a vacuum system is simply vacuum from the moving part all the way to the intake manifold but that is just semantics and the science/physics side of the discussion could go on for ever. It is best to just agree on a set of nomenclatures and stay with them through the entire discussion.
So to complete my reply to your original questions:
Quote:
1 As to the plumbing considerations - I was confused by a thread on a non-jeep discussion group discussing the installation of such a pump. What you say makes sense. However, adding to confusion was a series of posts I read on this site discussing teeing off the line from the pump and tying into a hole in the manifold near the carb.....something related to positive crankcase ventilation.
2 If I understand you correctly, I should be fine if I simply tie the positive pressure side of the pump to the manifold fitting and adjust the carb accordingly.
3 On a related topic, when I try to move the actuating arm on the pump by hand, it is extremely stiff. Is it supposed to be that way? When I opened it up it doesn't appear that it has been used since it was remanufactured and it moves freely when the big spring is removed.
1-The PCV system is "T"'d to the the line that runs from the pump to the intake. In this case the "P" in PCV is not for Positive Pressure but it is for Positive sucking of fumes from the crankcase using the intake vacuum.
2-Yes
3-Yes, it is suppose to be that way. The arm is heavily spring loaded as part of it's design to keep the lever pressed firmly against the cam that drives it throughout the RPM range. This why the wearing down of this driving cam is quite regular and is often the cause of poor fuel pump performance and is just as often overlooked when trouble shooting poor pump output. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
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