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double action fuel pump for 1956

Started by Hillbillycat, July 30, 2020, 08:54:58 AM

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Hillbillycat

Hi,
is there any double action fuel pump out there that fits a 1956 365 engine? Would be an easy fix to boost vacuum for better wiper action during acceleration. My stock vaccum booster pump is worn too much - I get only 8" Hg max on that line. Flapper valves are OK.
My other option would be a HELLA 12V vacuum brake booster pump with micro switch on the bowden cable. But a double action pump would be a way smarter way of dealing with the issue and more eye appealing than a electric pump tucked away somewhere in the engine bay.

My pal's 1950 Pontiac flathead six has a pump that looks like it would fit. These pumps don't float around here in Germany so no way of stumbling across a few and checking for fit. That's why I ask you guys.

Thank you


J. Gomez

Quote from: Hillbillycat on July 30, 2020, 08:54:58 AM
Hi,
is there any double action fuel pump out there that fits a 1956 365 engine? Would be an easy fix to boost vacuum for better wiper action during acceleration. My stock vaccum booster pump is worn too much - I get only 8" Hg max on that line. Flapper valves are OK.
My other option would be a HELLA 12V vacuum brake booster pump with micro switch on the bowden cable. But a double action pump would be a way smarter way of dealing with the issue and more eye appealing than a electric pump tucked away somewhere in the engine bay.

My pal's 1950 Pontiac flathead six has a pump that looks like it would fit. These pumps don't float around here in Germany so no way of stumbling across a few and checking for fit. That's why I ask you guys.

Thank you

I do not think there is one that would fit-in as a replacement.   ???

That is one of the few things that Cadillac did as the worse design placement for the vacuum pump.   >:(

If your wiper motor and pump are working correctly they would need about 12-15” Hg to function. Is your pressure at idle or high RPM?

8” Hg at idle would be about right, engine vacuum would be greater so the vacuum pump is not online (vacuum manifold flapper at the firewall from the pump is closed) only at higher RPM the vacuum pump would increase the volume to the line.

If you go with an electric vacuum pump option (which I think would be best option if you want to keep the same wiper motor and pump), you will need to disconnect all the vacuum lines at the vacuum manifold and just hook up the wiper motor and washer. You do not want the extra vacuum from the electric pump to feed the throttle check valve, this would need to be connected to engine vacuum only.   ;)

In my case I converted both to electric as I want reliability, I removed the hex key from the oil pump that drives the vacuum pump and added a thing aluminum plate between both as a cover.

Good luck..!   
J. Gomez
CLC #23082

Hillbillycat

Hi,
already assumed that non would fit. Is it just the lever shape and lenght that is engine specific. ´Cause that one could be changed for one of a 56 pump, couldn´t it?

Unfortunately that 8"Hg is at high rpm :-(
I planned to hook the pump to the same vacuum hose that the booster pump is hooked up. That would be the vacuum manifold with flapper valves at the firewall. But you´re right about hooking up on the wiper/washer directly. The electric pump will draw the same vacuum as soon as it´s powered whereas the original booster pump had variable vacuum draw hence the need for the flapper valves. Am I right here?

Thanks

fishnjim

Off top of my head, I can't think of one, but I'll go down and look in my books.   Post later.
From what I recall most of those(stacked models) were side mounted through the block, where these fit the shorter "rod" type actuator.   
If the bolt pattern fits, possibly you could adapt the lever from a '56 FP to the dual  version, but playing with ideas.   
As you're aware the sell vacuum pumps for this issue.   But I'll throw out you can go to electric wipers just as easily.   www.netportwipers.com    That's what I did as I know the pains of early vacuum systems.   Uses the original wipers just adds the motor and controls.
Easier to adapt am electric WW washer pump also.


J. Gomez

Quote from: Hillbillycat on July 30, 2020, 10:37:09 AM
Hi,
already assumed that non would fit. Is it just the lever shape and lenght that is engine specific. ´Cause that one could be changed for one of a 56 pump, couldn´t it?

Well everything is possible, it could be as simple as swapping the lever or a more complicated in re-doing the complete pump.

You need to have both on-hand to compare them fit, pump diaphragm travel, pressure, fuel pump rod, etc. 

Quote from: Hillbillycat on July 30, 2020, 10:37:09 AM
I planned to hook the pump to the same vacuum hose that the booster pump is hooked up. That would be the vacuum manifold with flapper valves at the firewall. But you´re right about hooking up on the wiper/washer directly. The electric pump will draw the same vacuum as soon as it´s powered whereas the original booster pump had variable vacuum draw hence the need for the flapper valves. Am I right here?

Yes, you could hook the electric vacuum pump up to the firewall manifold and turn it on when you need it to feed both the wiper motor and washer, BUT you will need to disconnect the line from it going to the throttle check valve. The throttle check valve will connect to the main engine vacuum.

I’m attaching a drawing I did showing the vacuum lines from and to the main manifold at the firewall with the additional line to the throttle check valve, unfortunately this layout is not included on the Service Manual.

Hope this helps  ;)

Good luck..!
J. Gomez
CLC #23082

35-709

"As you're aware the sell vacuum pumps for this issue.   But I'll throw out you can go to electric wipers just as easily.   www.netportwipers.com    That's what I did as I know the pains of early vacuum systems.   Uses the original wipers just adds the motor and controls.
Easier to adapt am electric WW washer pump also."


That should be www.newportwipers.com if you want to check out that option.  I would go with the electric wipers from Newport also.
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

cadman56

Block off the hose that goes to the washer pump, see if that increases you vacuum.
Also, check to manifold on the firewall to see if the two flappers are holding.  I had to replace the rubber diaphragm that David King was making for awhile.
Since I tend to be apurist I made sure my systems all worked like intended and boy were they great.
Good luck.
1956 Cadillac Coupe deVille (sold)
1956 Cadillac Convertible (sold)
1956 Cadillac Eldorado Seville (sold)
1967 Cadillac Eldorado (sold)
1968 Cadillac Convertible (Sold)
1991 Cadillac Fleetwood Brougham dElegance
Larry Blanchard CLC #5820

fishnjim

Thanks for correcting my typo, 35-709
The discussion about minimizing vacuum leaks is one to pursue in any event.

Your 56 calls for a AC 4269 fuel (only) pump.   
The rotary vacuum pump is AC-4076.   If you decide to repair/rebuild/replace.  I think there's a test for it in the shop manual.   Disconnect  and stick a gauge, flow tester on it.
Interchange shows no dual items.   
The other two issues besides bolt hole fitment are; delivery - pumping volume, pressure(max), and stroke.   So even if you could find a dual pump you have to have one that does all four or you'll starve your motor, blow gas out the carb, or not meet rating capacity.
That reduces the likelihood and then you have to locate one after you identify it.   Further reducing your odds.   
I think that's probably why the after market has come up with these other solutions.

Hillbillycat

Thanks for all the input.

As far as I know there are zero vac leaks on my car. But I´ll block the washer pump hose again and check for increase of vacuum. Diaphragm on the firewall manifold is good and working.

I think I´ll try the electric brake booster vacuum pump with micro switch on the bowden cable. Read in a different thread that someone tried a cheap chinese 12V vac pump that did not work for that purpose. I hope the brake booster vac pump whill draw more vacuum and volume.

fishnjim

I'm not that familiar with the '56 particulars, as much, but does it have a vacuum reservoir?   That was common for the brake booster, so they'd work better.   Could add one, if not.
But I'm a believer better to fix what's broken than apply a work around, up until no more parts avail.

Lexi

That car would have a vacuum reservoir, driver's side near firewall/fender cowl. Clay/Lexi

Joe G 12138

A 1953 and older dual-action fuel pump will not not be a drop in swap for the 1954 and later single action fuel pump if the '54 and up water pump and heater hose configuration is as factory. The year they went to the smaller, shorter single action pump, they changed the water pump heater hose outlet locations and routed a hose through where the vacuum part of the previous pump used to be.   Joe Gibeault ('50 + '55 Cad, previous '56). 

Hillbillycat

Got the pump and will try it asap.

In case it won´t work - is there a writeup on how to rebuild the vacuum booster pump inside the oil pan? I´d love to have that one work, but found no info online. Only that there are no rebuild kits are available.


J. Gomez

Quote from: Hillbillycat on August 03, 2020, 03:34:00 AM
Got the pump and will try it asap.

In case it won´t work - is there a writeup on how to rebuild the vacuum booster pump inside the oil pan? I´d love to have that one work, but found no info online. Only that there are no rebuild kits are available.

There are a few post here at the CLC and one at the AACA detailing the Buick which shares some commonalities with the Cadillac.

http://forums.cadillaclasalleclub.org/index.php?topic=123171.msg223273#msg223273

https://forums.aaca.org/topic/184502-how-to-do-series-a-full-discussion-on-the-mysterious-1957-58-buick-vacuum-and-oil-pump/?tab=comments#comment-921368

Good luck..!
J. Gomez
CLC #23082

fishnjim

The vacuum pump piggy backs on the oil pump.   There's a connector "key" that drives the rotor.
The pump uses vane technology.   I have some pictures, but I think once you get the an off, the whole assembly unbolts then you can rebuild on bench.   The distributor shaft runs the pumps.   If the vanes/stator are worn/damaged, then you might have to find a spare or gets some made.     
Probably just seal failed, dirty oil got in, and gummed it up, but a guess.   

Hillbillycat

Well, tested the electric HELLA break booster pump yesterday. Won't work for that purpose. The pump got smoking hot after just 30 sec of running. The vacuum itself was strong enough to operate the wipers on the dry windshield however.

Looks like I need to pull the pan and see if I can rebuild (or have rebuild) the original rotary pump.

I assume the vanes to be some sort of fiber stuff that needs to be custom made.

fishnjim mentioned a seal failure. Well that could very likely be for I had a seal failure on the oil pump to engine block mating surface resulting in oil pressure loss when the oil got warm. Too bad I didn´t insist on getting my hands on the vacuum pump when the pan was off in the shop due to that repair.


I took the car out into the rain yesterday just to check the wipers again. They operate at both speeds at idle. As soon as I lightly touch the gas pedal they stop (typically exactly in your vision :-) Same if I have to apply the brakes or hold them for some time. That makes me think if the motor itself may be weak.
Another thing I noticed that might be of importance is operation on slow (wide wipe) mode isn´t one smooth wipe however. As soon as the blades meet the panoramic curve they slightly "hang up" and then catch on from that little interruption. Does that indicate any issue or is it a normal action?

Don´t want to pull the pan and mess with the rotary pump if the wiper motor itself is weak, too. Electric conversion would make more sense then.
I´d love to keep the original fancy vacuum system, but not by all means.


fishnjim

Should look something like this inside.  Seal are just o-rings.
It can still leak through the pump, if not closed off.   

J. Gomez

Quote from: fishnjim on August 05, 2020, 09:28:40 AM
Should look something like this inside.  Seal are just o-rings.
It can still leak through the pump, if not closed off.

Jim,

I do not believe there are any seals or “O” rings on either the oil or vacuum pump, at least the ones I have did not have them.   ???

There is a gasket for the oil pump housing and a felt washer at the pick-up tube which must be install to avoid intake leaks for the oil pickup.

Oil will get into the vacuum pump during operation to keep the vanes lubricated but the oil “should” be block by the vacuum valve on the right side of the block just behind the starter, if it is working correctly.

High engine vacuum would keep this valve close so no vacuum and/or oil is suck into the line, once engine vacuum is low it would open to allow the higher vacuum from the pump to feed the line.

If the valve is defective it will cause oil to be suck into the line and go into the cylinders, folks have had issue with oil burning cause by a defective valve. Once they disconnect the line from it everything goes back to normal.   :(

Hope this helps…!
J. Gomez
CLC #23082

Roger Zimmermann

I can confirm: no O-ring at the oil or vacuum pump.
1956 Sedan de Ville (sold)
1956 Eldorado Biarritz
1957 Eldorado Brougham (sold)
1972 Coupe de Ville
2011 DTS
CLCMRC benefactor #101

fishnjim

#19
Either way, needs to be fixed.   
Don't know how this string got strayed from fuel to vacuum?   I'll study my spare pump again probably confused with what I've been working on.
A better view of the two halves