VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 What is the seal on the vaccum line to fuel tank

I am trying to get my fuel vacuum tank operating again on my '28. I found that the vacuum line between the intake manifold and the vacuum fuel tank has some sort of packing material as the seal in place of a brass compression fitting. The current material is hard and may not be providing the seal since the tubing is loose.

What can I use to repack this seal? I do not think I can use a brass slip compression fitting with the style of packing nuts.

Any thoughts.

Leaving the packing material in place, I suggest working a bunch of thick, plumbing-thread-sealing-goop around the vacuum tube and on top of the packing material. Also, put some goop on the fitting threads.

I know, this system sucks.

Cheers, Dean

Hi Rustoholic,
'25's used several turns of hemp string. I usually rub in some grease into the string to help make the seal. This joint allows some movement as a solid joint would encourage breakage of the pipe as there is movement between the engine and cowl where the vacuum tank is mounted.

Regards
Al

Hi

Why muck around with goop or muck when if you do it once and do it right will be the last time. A compression olive or flared end depending on what fittings you have will see you out. Did mine over 20 years back with a loop in the line to take any movement, fine, no problems. All this talk about slopping things around the join does not seem the right way to go.

Who knows you may even want to even fit a new bit of tubing?

But then to each his own.

The main thing is that you are happy in the end.

Good luck, hope you fix the problem.

Cheers

Ray

I agree.
Fix it properly once and for all with olive compression fittings.My '25 has had these since new I believe, therefore also '28 I would think. I have had my car since '68 and have never had to attend to them.
Copper can work-harden (vibrations) and crack and as mentioned one often sees full circular loops in both the vacuum line and fuel feed line to the carburettor to overcome this tendency. Mine are not set up like this and routed direct. Again no problems in all these years. Anyway if you suspect your lines are getting brittle, remove them and anneal them by heating to dull red and allowing to air cool. Fixed.
But I would definitely be changing your cobbled together present set up to proper fittings and eliminate any future problems whilst out driving.The fittings are quite cheap and readily available as is new copper pipe if yours are a bit short after trimming the ends back to sound material.
Vacuum tanks must have airtight fittings all through to work at their best and can be extremely reliable.
Whilst on the subject I have fitted an in-line filter under the floor boards to trap dirt and rubbish from the tank before it gets to the vacuum tank. A filter between the vac tank and carburettor is useless, the damage (blockage) already done at entry to the vac tank. The filter I use is a simple plastic push on type laying on its side in the fuel line out of sight. With this in place I have trapped lots of dirt etc, but have never had any problems with the vacuum tank and not once had to disassemble it for attention in more than 40 years.
Easy fix, so go for it.
Cheers.

You guys are missing my point. I believe the original pipe, inlet manifold end, successfully used a packing under the nut and was a joint designed to allow movement. I don't believe an olive was used at that end at all.

Regards
Al

Ray& Rusty

I did not use a compression fitting since I would have to add another fitting inline to attach to the current fitting that is not set up for a compression or a flare. How did you tackle that?

Hi Mike,

All the Stewart Warner Vac Tanks I have seen so far, and bare in mind things can be changed over 78 years, have most commonly the
compression olive and appropriate fitting or a flanged tube and appropriate fitting. Replacement fittings for both types are commonly available.

Cheers

The three USA '28 Chevrolets I own have a flexible fitting on the vacuum line at the vacuum tank. I haven't done an analysis on the material as have never taken one completely apart. I would think that properly sized leather or modern rubber rings could be used. Not sure if o-rings would have enough flat cross section to seal but it is worth a try. Or you could cut or punch out rings from a flat rubber pad. The rubber should be gasoline and alcohol resistant as when the float does not work correctly gasoline can be drawn directly past the seal and into the intake manifold.