Carb to distributor vacuum line size

[Davidcc]

Car is the 1938 Plymouth Coupe RoadKing with stock 201 and a Carter W-1 carb.  What is the recommended inside diameter of the vacuum line going from the carburetor to the distributor? Thanks 

[Doug&Deb]

I believe it’s 3/16 and the ends are 1/8-27 npt pipe.

[desoto1939]

suggest that you use the Nickel Clad tubing because of the bending that the air line has to do to connect to the carb and distributor.

 

Rich hartung

Desoto1939@aol.com

[Ivan_B]

14 hours ago, Doug&Deb said:

I believe it’s 3/16 and the ends are 1/8-27 npt pipe.

Maybe 3/8-24 UNF? 🤔

Edited June 7 by Ivan_B

[Los_Control]

I think @Doug&Deb is correct here, it is a really small line. Measures 3/16" OD .... no idea what size fittings and threads for that line.

 

 

 

[chrysleritis]

Often you see various conversion fittings on those things that have accumulated over the years. For what it's worth, my Chrysler parts book shows that in 1938, there was a standard nipple coupling that converted the double-flare tube fitting to the female input to the distributor vacuum chamber and also on the other end to the manifold. The manifold likely has the 1/8-27 pipe thread. They wanted you to use double-flare tubing for the oil gauge line, the distributor vacuum line, and a couple of places in the brake system. I think 3/16" tubing is right, and the flare nuts are 3/8-24. And yeah, leave extra length and use the flexy nickel-copper tubing. 

[D35 Torpedo]

Regular steel tube is fine. Even just a premade brake line will work fine as long as the brass fittigs are in place. Just bend it to fit. 

[chrysleritis]

Oh sure, you can just grab a length of steel stuff from the local auto parts joint. But if you have leftover nickel-copper stuff from the brake job, that's nice. 

[Ivan_B]

Length of nickel-copper stuff is also available at the local auto parts joint

[DJ194950]

Last time I went to a Napa store to buy a premade 3/16" brake line all they had in stock were made with the copper/nickel,  stuff.  I did not ask if they could get one from regular steel.  The copper stuff bent easily and  was easy to flair as I wanted to make the length different.

 

Check it out?

 

DJ

[Los_Control]

I actually found brake lines hard to come by .... I have 2 auto parts stores in town, one simply had no steel lines and nicop was not available at their warehouse.

The 2nd store had some steel lines but not nicop .... the only steel lines available was what is on the rack in the back ... they would not be replaced when sold.

 

I'm just suggesting my only means to get nicop was order online .... hope others have better luck.

[Ivan_B]

Our local Autozone has both copper and steel lines available, and they are cheaper than other places too. Online is even more cheap, especially if you want to do the whole car at once.

[Doug&Deb]

Be careful what you buy online. I’ve seen line advertised as nicop really cheap. It’s actually copper coated.

[Davidcc]

Thank you folks.  Very helpful.  Esp. pictures and "various conversion fittings" comment as the original question came from not being sure what the original set-up was/and is needed.  I now believe a 3/16" (maybe 1/4") line will suffice and I will give the copper/nickel combination a try, being used to only steel line.  One additional issue involved is how to be able to make the final turning adjustment of the distributor when using a solid, non-flexible line (do a coil at one end of the solid line?)  I do not want to use a plastic or rubber line. 

Thanks again. David

[Los_Control]

I say just make the line a little long, you will be able to flex it enough to do your adjustments.

That is the way my original steel line is and works fine .... nicop is pretty flexible, same time any small line is including steel.

 

One advantage though, it is pretty simple to just unbolt the distributor and work on it on the bench instead of leaning over the fender standing on your head.

The rigid line does hold in place and when you drop it back in and timing should be really really close to where you took it out.

[Ivan_B]

8 hours ago, Doug&Deb said:

I’ve seen line advertised as nicop really cheap. It’s actually copper coated.

Good point, but you have to read those amazon ads carefully. They do say it is nicop, but do not actually state that it is 100% nicop (reminds me of the free vs. absolutely free stand-up joke). Anyway, technically, this is not a misleading/false advertisement. They just list the best point (line is nicop) but hide the worst (only nicop-coated).

Also, I just found-out myself that "fill synthetic" and "100% synthetic" motor oils are actually not the same thing.

 

1 hour ago, Davidcc said:

One additional issue involved is how to be able to make the final turning adjustment of the distributor when using a solid, non-flexible line

The adjustment you need to do is very-very minor... Also, does your vacuum unit still holds vacuum? Mine sure doesn't

 

1 hour ago, Los_Control said:

One advantage though, it is pretty simple to just unbolt the distributor and work on it on the bench instead of leaning over the fender standing on your head.

The rigid line does hold in place and when you drop it back in and timing should be really really close to where you took it out.

Do you actually have the equipment to do the timing/vacuum advance on the bench? Also, how would you close-fit the metal line without having everything mounted on the engine? Or are you talking about taking the old line off and duplicating it on the bench, or something like that? 🤨

[Los_Control]

6 minutes ago, Ivan_B said:

Do you actually have the equipment to do the timing/vacuum advance on the bench? Also, how would you close-fit the metal line without having everything mounted on the engine? Or are you talking about taking the old line off and duplicating it on the bench, or something like that? 🤨

Absolutely no to all those questions. You need to time the engine with it running and distributor installed.

What I am saying, is my engine is timed and runs pretty well. I have needed to work on the points a few times and I have removed the distributor at least 3 times since 2018.

I need to do it again  because I'm fighting a issue and not positive what the issue is. .... I'm going to change condenser and see if that helps.

 

To change the condenser I'm pulling the distributor out and set it in my bench vise .... while there I will check everything else.

Then when I set it back in, and the hard metal line aligns perfectly, I'm putting it back in exactly where I pulled it out from.

 

I blew up my back many years ago and I simply would prefer not to bend over the fender to work on the distributor. It is a simple 7/16" wrench to disconnect vacuum then 1 hold down bolt.

 

 

The photo shows a crappy 75 year old steel line that works fine. Some sort of imitation of swoopy coming out of the distributor then tall up and over the plug wires on the head.

Honestly I feel the distributor has a very short turn radius, but because of the 2nd adjustment underneath you have all the adjustment you need.

And a generous length hard line there is all the adjustment you need.

 

 

[desoto1939]

3 hours ago, Davidcc said:

Thank you folks.  Very helpful.  Esp. pictures and "various conversion fittings" comment as the original question came from not being sure what the original set-up was/and is needed.  I now believe a 3/16" (maybe 1/4") line will suffice and I will give the copper/nickel combination a try, being used to only steel line.  One additional issue involved is how to be able to make the final turning adjustment of the distributor when using a solid, non-flexible line (do a coil at one end of the solid line?)  I do not want to use a plastic or rubber line. 

Thanks again. David

 

Some people taken the plastic weedwacker trim line and then insert it into the end were the small bend its.  filling the tube with the plastic trim line gives support and also helps prevent the tube from getting to sharp of a bend and the plastic fills the space to support the tubing.

 

Try it on a piece of tubing and see how it works for you.

 

Rich Hartung

Desoto1939@aol.com

[Sam Buchanan]

3 minutes ago, desoto1939 said:

 

Some people taken the plastic weedwacker trim line and then insert it into the end were the small bend its.  filling the tube with the plastic trim line gives support and also helps prevent the tube from getting to sharp of a bend and the plastic fills the space to support the tubing.

 

Try it on a piece of tubing and see how it works for you.

 

Rich Hartung

Desoto1939@aol.com

Nicop is so easy to bend by hand that no special technique or insert should be needed. Just bend gradually and slowly and tight radius bends are possible.

[Ivan_B]

36 minutes ago, Los_Control said:

To change the condenser I'm pulling the distributor out and set it in my bench vise .... while there I will check everything else.

Then when I set it back in, and the hard metal line aligns perfectly, I'm putting it back in exactly where I pulled it out from.

Got it. You really should not need to take it out to put in a new condenser, though. It is just two screws - one holds the condenser, another one - the wire lead. It will probably require more effort to get to the distributor clamp screw and pull the vacuum line off

 

For bending metal tubing, so that it looks professional, it us useful to just get a cheap manual tube bender (groovy cylinder with a handle). If you are getting a simple flaring tool (and you are, if you plan to do your own tubing), some of them already come with a simple bender as well. The local parts store probably have all those for loan too.

[Los_Control]

I get what you are saying @Ivan_B I just want to say that bending 1/4" steel lines is easy. .... I'm not claiming this is the best job ever. I bent 1/4" steel lines for my rear brakes and feel it looks presentable. I do have a decent tube bender .... this was all done by hand and not worth bringing the  bender out.

There is a 90 degree bend going into the wheel cylinders and think I used the bender for those .... sure I could have gotten by without it.  nicop is even easier to work with.

 

 

As far as the condenser goes, I know it can be done on the side of the road if needed. I just prefer to pull it.

In fact if you scroll up and look at my first photo .... you see a custom made condenser and that is connected to the coil to replace the condenser in the distributor.

 

I was told by the creator .... I dunnno I never ran one that far away from the points .... they are designed to bolt to distributor body. Near the points.

 

Others have told me yeah! that will work fine. ..... I say it starts and runs fine .... let it sit and idle for about 45 minute and it just gets a weak spark and dies .... let it cool down and will run fine again.

 

I thought I was smart and I just disconnected my known good oem condenser and left it installed .... all I need to do is connect the wire for the condenser and disconnect the aftermarket condenser ..... Thats how simple of a job I need to do ... Yeah I'm pulling the distributor to connect that wire. ..... I do not need to, it is such a simple job I will and that allows me to inspect the condition on everything else.

 

 

[Ivan_B]

Your lines look fine, you've got some great bending skills

For the spark issue, I assume you've already tried swapping the coil, so I would not suggest that. I suppose the condenser might go bad with heat too. Another way to check is to try cooling it down (maybe using an air can spray, etc.?) to see if your spark comes back without the need to wait for the engine to cool down.

[Los_Control]

10 minutes ago, Ivan_B said:

For the spark issue, I assume you've already tried swapping the coil,

Actually not .... the problem I have is self inflicted but I saw no other way .... I'm just doing the 12 volt conversion and installed new ballast resistor, coil, wiring, points, condenser .... I changed too many items all at once. .... It could be a faulty new item on any of them .... I'm just picking on the condenser first because it is somewhat shady installed. .... just as easy could be the new ballast resistor or new coil .... Still in the middle of the engine swap on wife car and just no time to look at it.

[Sam Buchanan]

Just for info sake, if a 12v coil is installed it doesn't require a ballast resistor. The standard 6v coil will need the resistor in a 12v conversion.

[Los_Control]

We really getting off topic here and stealing @Davidcc thread about vacuum lines.

 

@Sam Buchanan It depends on which coil you buy.

Not all coils are created equal  and some require a external resistor and others do not.