Vacuum booster pump connections

TodFitch · November 22, 2006, 01:16:52 PM

Quote from: 12905 on November 22, 2006, 02:02:09 AM
I did know of a couple of cases in which owners hooked up vacuum reservoirs between the engine and the wiper motor. Unfortunately, I can't remember where the tanks came from. I'd like to put one on my 36.

My 1991 Jeep Cherokee had a fairly large vacuum reservoir inside the front bumper on the passenger side. It did allow the AC controls to work for a fairly long time after the engine was turned off.

I found that my local auto supply store stocks a number of vacuum system parts including a small reservoir with built in check valve. I tried one under the dash on my 1933 and it did allow the wiper motor to go a stroke or two after the engine was shut down. I pulled it off for two reasons: 1) It was too small for any real use on the road (I'd like it to last at least 15 to 20 seconds on full throttle acceleration). 2) It had an annoying rattle that was most evident when coming off idle (like starting up from every intersection).

If I were to do it again, I'd go with a large reservoir and try to find a place to hide it where any sounds would not annoy me.

Jim Yergin · November 22, 2006, 10:15:39 AM

That's interesting about the wear issue. I had never heard of that.

Chet, I agree with you. After running the engine and checking the open lines, it appears that the line to the front is the exhaust and the line to the rear is the inlet.

Don, attached is a picture of my setup. I found the pump on eBay.

Happy Thanksgiving everyone.
Jim Yergi

12905 · November 22, 2006, 02:02:09 AM

I wouldn't be too enthusiastic about using a double diaphragm pump. They had a bad history in their day for causing excess wear on the cam eccentric that drove them. This problem was not confined to one car line. I worked in a reman plant for a few years and we got many an engine with the eccentric worn down to the point where the pump wouldn't deliver either gas or vacuum. I also worked on Chryco vehicles for many years, and I don't recall ever seeing a dd pump on one of them. I don't think Chryco ever pushed them, except perhaps on Imperial.

I did know of a couple of cases in which owners hooked up vacuum reservoirs between the engine and the wiper motor. Unfortunately, I can't remember where the tanks came from. I'd like to put one on my 36.

chetbrz · November 21, 2006, 05:42:33 PM

Quote from: TodFitch on November 21, 2006, 03:48:45 PM
It is my understanding that if you are not using the vacuum side of the double acting fuel pump that you should block it off to reduce wear in the pump. As I heard it, with the inlet open the pump will be doing a full stroke of its diaphragm on every cam rotation but if the inlet is blocked (or connected to a vacuum system without leaks) then the diaphragm will be basically stationary after it pulls the vacuum which reduces wear on the moving parts in the pump.

Thanks Tod,

That's good to know.? I am not driving the 48 yet but I will plug the input to the pump until I hook the vacuum lines up again.? Probably also a good idea to keep dust & dirt out.? I certainly have a lot of that floating around the garage these days.

TodFitch · November 21, 2006, 03:48:45 PM

It is my understanding that if you are not using the vacuum side of the double acting fuel pump that you should block it off to reduce wear in the pump. As I heard it, with the inlet open the pump will be doing a full stroke of its diaphragm on every cam rotation but if the inlet is blocked (or connected to a vacuum system without leaks) then the diaphragm will be basically stationary after it pulls the vacuum which reduces wear on the moving parts in the pump.

chetbrz · November 21, 2006, 01:01:08 PM

Quote from: Jim Yergin on November 15, 2006, 12:24:44 PM
On my 1941 P12 Plymouth I am replacing the original fuel pump with one that also has the vacuum booster pump (Mopar part #688482). Does anyone know which fitting (front or rear) on the booster pump is the exhaust and which is the inlet? In other words, which line runs to the intake manifold and which line runs to the wipers?
Thanks.
Jim Yergin

Jim,

I have one of these on my 48.? I haven't hooked up the vacuum lines yet but I believe the left side is the vacuum side and the right is the exhaust.? My assumption is that the exhaust side goes to the intake manifold and the left side goes to your vacuum devices.? ?Once installed and with the motor running you can feel the vacuum at the connector.? ?This way you can?t make a mistake.? Someone also mentioned that cars that used this device also had an accumulator tank to increase the available volume of vacuum.? Probably not necessary but just thought I would mention it.

Chet?

Quote

PS... The top is the Vacuum and the bottom is the gas.? The gas input is the bottom right. The bottom left goes to the carb.

chetbrz · November 21, 2006, 12:56:33 PM

Quote from: Jim Yergin on November 15, 2006, 12:24:44 PM
On my 1941 P12 Plymouth I am replacing the original fuel pump with one that also has the vacuum booster pump (Mopar part #688482). Does anyone know which fitting (front or rear) on the booster pump is the exhaust and which is the inlet? In other words, which line runs to the intake manifold and which line runs to the wipers?
Thanks.
Jim Yergin

Jim,

I have one of these on my 48.? I haven't hooked up the vacuum lines yet but I believe the left side is the vacuum side and the right is the exhaust.? My assumption is that the exhaust side goes to the intake manifold and the left side goes to your vacuum devices.? ?Once installed and with the motor running you can feel the vacuum at the connector.? ?This way you can?t make a mistake.? Someone also mentioned that cars that used this device also had an accumulator tank to increase the available volume of vacuum.? Probably not necessary but just thought I would mention it.

Chet?

Don Coatney · November 21, 2006, 07:29:05 AM

Quote from: Jim Yergin on November 16, 2006, 10:30:44 AM
Plymouths,
That is exactly what I did last night and it appears I do have it corrected correctly.
Thanks for your suggestions.
Jim Yergin

Jim;
What was your final soloution? Vacuum on top, fuel on the bottom? Can you post a picture? Where did you find your vacuum boost fuel pump?

Jim Yergin · November 16, 2006, 10:30:44 AM

Plymouths,
That is exactly what I did last night and it appears I do have it corrected correctly.
Thanks for your suggestions.
Jim Yergin

FourDoor · November 16, 2006, 12:14:25 AM

I've never worked with one,Jim, but I would suspect if you install it and start the engine and then? one end would suck and the other would blow. You should be able to figure out which is which by putting a finger over the tubes.? The blow end would go to the manifold and the other end to the wipers? No maybe not.? But in any case I would assume that if you get it right the wipers would not stop so readily under acceleration and the other way they I would suspect it would be worst than without the booster at all. But I don't think you would do any damage by trying the different hook ups until you get the right one. That's what I would do.? ?

Jim Yergin · November 15, 2006, 12:24:44 PM

On my 1941 P12 Plymouth I am replacing the original fuel pump with one that also has the vacuum booster pump (Mopar part #688482). Does anyone know which fitting (front or rear) on the booster pump is the exhaust and which is the inlet? In other words, which line runs to the intake manifold and which line runs to the wipers?
Thanks.
Jim Yergin