28Q29U Plymouth Forum

General Category => General Discussion => Topic started by: Russ T. Fender on November 23, 2021, 10:44:48 AM

Title: Vacuum tank
Post by: Russ T. Fender on November 23, 2021, 10:44:48 AM
Does anyone know what the proper size is for the line running from the oil pump to the vacuum tank?
Title: Re: Vacuum tank
Post by: chetbrz on November 23, 2021, 12:34:34 PM
1/8" soft copper tubing.  It's been a while since I thought about this so please review the attached project post for conversion information.

FYI... 186 miles since I primed the pump and still working without issue.   

http://www.1948plymouth.info/1929/Work_files/2019/12162019.htm (http://www.1948plymouth.info/1929/Work_files/2019/12162019.htm)

PS... This is what I did there may be other solutions I'm not aware of.
Title: Re: Vacuum tank
Post by: Russ T. Fender on November 23, 2021, 01:32:15 PM
Thanks, that was what I thought but better safe than sorry.  I have a few 2lb coffee cans with odd old fitting and I am hoping I can sort through them and configure the line with just one fitting on each end.  Probably not but it's worth a shot.  Thanks again and Happy Thanksgiving!
Title: Re: Vacuum tank
Post by: 29UJohn on December 13, 2021, 10:46:15 PM
I replaced the 1/8 soft copper line on my 29 Plymouth with 1/8 90/10 copper/nickel after the soft copper line broke at the vacuum tank fitting while on a Saturday morning drive.  Amazing how fast the oil will pour out of the tiny line when it brakes.

Opps!  I was talking about the other 1/8 copper line, the one to the oil gage. On my engine both come off the oil/vac pump, although on some it comes off the other side of the engine.  Both lines are 1/8 copper.  I changed both to 90/10 copper/ nickel.  The vibration eventually broke the oil pressure line at the fitting.  Had to call my wife and she brought me the tools to repair it so we could drive it home. 
Title: Re: Vacuum tank
Post by: chetbrz on December 14, 2021, 07:11:43 AM
That doesn't sound right.  The line going to the vacuum pump should be sucking air.., not blowing out oil.  Looking at the pump.., were you connected to the left side of the 'T' fitting.   If the line breaks oil pressure might drop about 5 psi but it shouldn't expel oil.  The top 'T' fitting is the pump input.  This should be sucking oil into the pump.  Something doesn't sound right.

(http://www.1948plymouth.info/1929/images/Build/Motor22.jpg)
Title: Re: Vacuum tank
Post by: Russ T. Fender on December 15, 2021, 01:24:06 PM
I have always been concerned about the line to the vacuum tank fracturing.  While the engine does not flex that much there is constant vibration and some flexing.  I was going to put a loop in the line to absorb some of the vibration but was afraid that might affect the efficiency of the vacuum pump.  I have a thick wall 1/8" copper line but don't know what the composition of it is.  It looks like the line that broke is the soft copper tubing used for refrigerator ice makers.  Its flexible but not very strong. 
As far as the pump blowing oil out the line to the vacuum tank is concerned, I expect that it is possible.  The vacuum is maintained  because it is either sucking gas or shut off when the float closes the needle valve.  If neither of those  things are present the vacuum drops off and I think it would then be possible for some oil to be blown out the opening.  That's why it is so important that there be no air leaks in the system for the vacuum tank to operate properly.  Just a thought! 
Title: Re: Vacuum tank
Post by: chetbrz on December 15, 2021, 05:59:50 PM
If you are using a stock Kingston pump the float only affects the trapdoor between the upper tank and the lower.  Vacuum is constant from the pump and is only affected by engine speed.   The system is in equilibrium with motor speed which is reasonably predictable.   I am assuming that when the trap is opened by the float gasoline delivery is slowed into the upper chamber.  There is no check or shut off valve.  It's hard to wrap one's head around this device but it is very simplistic and inexpensive approach that works OK.., the majority of the time.

I would make sure you have strain relief on the plumbing.  A loop would be fine, just don't clamp the tubing down. 
Title: Re: Vacuum tank
Post by: Russ T. Fender on December 15, 2021, 07:13:29 PM
Looking at pictures of various engine compartments it looks like that line is anchored on some of them but not anchoring the line makes sense.  I have yet to make the connection and am not near the car right now so I am unclear as to how long the distance would be to leave unsupported.  If I am remembering correctly it isn't that long and using thick wall copper alloy tubing would probably be enough without a loop.  Does anyone have a picture of an unmolested set up?
Title: Re: Vacuum tank
Post by: chetbrz on December 15, 2021, 07:41:28 PM
You can anchor the line just don't tightened it down. Allow some movement. Mine is attached in one place to the firewall midway between the vacuum pump and the oil pump.  The line runs straight down along side the vacuum pump.  Then a gentle 90 degree turn into the oil pump.

You can use a piece of larger rubber vacuum hose to protect the clamp point.
Title: Re: Vacuum tank
Post by: Russ T. Fender on December 16, 2021, 09:48:30 AM
Sounds like the way to go, thanks.
Title: Re: Vacuum tank
Post by: 29UJohn on December 18, 2021, 01:08:24 PM
Opps - I was talking the oil pressure line that comes off the other side of the oil/vac pump to the gage, uses same 1/8 line.

:P
Title: Re: Vacuum tank
Post by: chetbrz on December 18, 2021, 01:35:05 PM
Quote from: 29UJohn on December 18, 2021, 01:08:24 PM
Opps - I was talking the oil pressure line that comes off the other side of the oil/vac pump to the gage, uses same 1/8 line.

:P

Wow.., I missed that completely.  I must be getting a little senile. 

My car has the in-dash oil gauge setup the same way.  I also have a modern gauge clamped to the steering column and tapped from the center oil port on the other side of the block.  My original gauge is also using the original tubing.  Fingers crossed !!