What size is the gas tank drain plug on '38 Zephyr

[Su8overdrive]

Need to remove the rusted drain plug from '38 Zephyr.   It is the factory original, four sides/square, not hex.  What is the exact size?  I need to put a lot of leverage on the wrench and don't want to round it. What wrench did you use?  I've rapped it with hammer after repeatedly squirting rust buster.    Need to drain tank yesterday.   Thanks

Edited January 2 by Su8overdrive (see edit history)

[gdcont]

You'll need to buy a good 8 point socket set. If I have a chance I'll check the set I have at work to see what size it is. Mean while keep spraying it with a penetrant  BP Blaster works good. Good luck. George. 

[Su8overdrive]

Yes, please. We need the size!

[19tom40]

Just use a 12" crescent adjustable wrench. Make sure that it is adjusted tight to the square and that you have 3 points of contact. I have tried many different types of wrenches on these and found that I get the best results with the crescent wrench. The fitting is a cast iron pipe fitting, so a regular wrench will not fit correctly.

 

I replaced mine with a brass fitting, so it will not rust in place.

[Su8overdrive]

No, crescent wrenches will not work on this one. Not snug enough. We've tried a couple.  We know to replace with brass hex.   But for now, need to know what exact size is this four-sided/square fitting.

[40ZephSedan]

I would use a pair of Knipex 12" parallel jaw pliers, the high lever ratio creates so much clamping force multiplier they are amazing, also work very well on rusted brake line fittings.

[Su8overdrive]

Thanks, but............................................................................. what   s i z e   is this square '38 Zephyr gas tank drain plug?  No one's giving us the    s i z e.    

[19tom40]

The size is 1/4-18 npt pipe plug. If you mean that you want the dimensions of the square fitting, I suggest that you measure it with calipers. The square is not a standard size because most of them were cast and then threaded. They can vary in size as much a 1/32". The size is quoted as a nominal 1/4".

 

If a 12" crescent does not give you enough leverage, you fitting is rusted in pretty solid and you will have to clean the tank so it can be heated to remove or soak it for a while from the inside with a mixture of acetone and automatic transmission fluid.

[Su8overdrive]

19tom40,  t h a n k   y o u,  Sir!      I'm a Packard guy trying to help my ex-Navy long-retired offline neighbor, whose immaculate '38 Zephyr town sedan this is.   Once this plug out, he's on easy street.

 

 I envy his soft life.  My '47 Packard Super Clipper despite rebuilt engine, good camshaft, new rebuilt WDO-531SA carburetor, new timing chain,  good power, revs smoothly, easily,  all that work,  but only 12 inches vacuum idle.  In fact, because of the low vacuum, the idle's set at 850 rpm, over  t w i c e   what it should be.  And it still dies every other intersection, so is undriveable.  Once on the freeway, you could drive it coast to coast in overdrive 75 mph at only 2,500 rpm all the way.  Wit's end.    

 

 I also thank GD & 40ZephSedan for their comments.  I long ago had a '40 Packard One-Twenty sedan.    Zephyrs get a bad rap simply as their engines need clean oil and open road running;  appropriately named cars because with their short stroke engines, they can run like the wind, same top speed as unblown 1936-37 Cords, which several friends had.  Zephyrs put out less torque per cubic inch than every engine of their day, Crosley included.  They are not low speed luggers.  But i knew of a fellow who drove his Zephyr back and forth between NYC and Boston in the day; 80,000 miles without major work.  Atalanta in England built some Zephyr-powered road cars, and three Jensen Model Hs used Zephyr engines instead of ohv nine-mained 260-ci Nash inline eights.  All these cars used Columbia rear axles, being built before the war.

 

  You know how well Lincolns did in the La Carrera Panamericanas.  Uncle Tom McCahill liked them.    Pardon the ramble.  Trying to distract myself from yesterday's drive, taking advantage of most people staying home, hung over, watching football.  New Year's Day and Stupor Bowl Sunday the only two (2) days a year in the greater Bay Area you can drive an old manual shift car relatively relaxed other than before 9am weekends.   

 

   But mine, per above, undriveable, and we are all stumped.  Happy New Year and thanks again.   

[19tom40]

Low vacuum can be caused by valve timing. If the chain is off just one tooth, it could cause this symptom.

[Su8overdrive]

Thank you, sir.  T h a t  was one of the first things double-checked.  Which is why we remain flummoxed.  I shouldn't hijack a Lincoln forum with my peccadillo as my focus coming here was to get info on my longtime friend and neighbor's '38 Zephyr gas tank plug.   Hard to imagine a nice, upper-medium-priced barouche would use iron and steel together, but apparently figured tanks not often drained?   My Packard had a steel plug, which i replaced with brass hex.

 

  For all my vintage knowledge, my mechanical skill limited to polishing metal, routine maintenance, working a grease gun 'til it airlocks.  There's a dearth of knowing old car mechanics in the East Bay, as throughout the nation, hence all the "retro rods" and Frankencars w/ ubiquitous SBC 350/Turbo Hydramatic.  Charm, history scrapped, lost, forgotten.  Curiously, i've heard some of the most "devout" members of the Horseless Carriage Club (pre-1916 automobiles) are those in their 20s, early 30s.

 

 Happy New Year and 10th day of Christmas to you and the other gentlemen on this fine site.