1950 Plymouth Special deluxe with carb leaking fuel and spark plugs carbon fouled

[CC7]

Good day to all, 

I am new to this forum and I am looking for some help regarding my '50 Plymouth Special Deluxe.

She is unrestored in great condition overall with 70k miles on it. Had some heavy hesitation under acceleration and serious misfiring so recently I replaced the plugs, ignition wire set, distributor cap, rotor and coil, also adjusted the float as to manual recommendations. After about 40 miles of driving over a one month period it now cuts out and having real problems starting and again if i get it going under any real acceleration it is hesitating and misfiring.  Quick look underneath and the carb is wet leaking a lot of gas and all the new plugs have heavy deposits of carbon on them(too rich??)  Checked the float again and seems ok , it is still the 1 bbl carter installed.

Anyone out there can recommend as to where things could be going wrong and where best to start with the diagnosis??

Any help much appreciated!

Cheers

[captden29]

the screws that hold the carb sections together can loosen, try to tighten them. most likely the carb needs a quality rebuild . vacuum advance diaphragms rot. check that and replace.timing?usually about 2 degrees btdc. check your manual. are the new wires steel core? look inside the cap for any burning. these new parts we get now are often low quality.   capt den

[CC7]

Thanks captden29 I will open it up and see. September last year there was a rebuild on the carb from a reputable gentleman. I will look at the timing again and have a closer look at the wires, the set was recommended by another Plymouth owner but you are certainly right about the quality of some of these new parts

[Branded]

A can od Sea Foam pored in the gas tank will clean up and deposits in the carburetor.

[knuckleharley]

What everyone else has said,and once you get it to where it will start and idle easily,the best way to get rid of the carbon is to let the engine warm up to normal operating temperature,then manually control the throttle while slowly DRIBBLING (NOT "pouring") a little bit of water down the carb throat a little bit at a time. Be prepared for loud,rude noises,as well as clouds of noxious black smoke as the carbon is blown out of the engine,the exhaust manifold,and even the muffler and tailpipe.

Once the clouds of smoke stop,stop dribbling the water,

It is a REALLY good idea to do this outside,not in your garage.

Keep in mind that if your muffler is very old and thin from rust,you might have to end up buying a new muffler,but you were going to have to do that soon anyway,so no big loss.

Also,pull your plugs and check the electrodes when done.  This can be hard on electrodes.

Edited October 14, 2017 by knuckleharley

[pflaming]

Old mechanics' trick.  I had a seasoned older machanic check my truck 218 engine. After a bit if adjusting by listening, he crossed wires 4 & 5. Engine started fine, but when he full throttled it, we got same quality back fires. I asked why he crossed the wires. He claimed the mis firing cleaned any loose debri from the carb. What ever, it is a smooth running engine. JMHE, not scientifically researched.  Engine as is.  I gave it a good prime coat with Jasco Prep and Prime, then five coats of rattle can clear for anti rust protection and an old engine look. I get lots of complements on it.  Air in Central Valley California does not require an air cleaner, LOL I removed it for these photos. 

 

Edited October 14, 2017 by pflaming

[Silverdome]

If you are using fuel with ethanol in it you will probably have to have a slightly lower float setting. Probably a 1/16" difference at most.

If the car sat with this ethanol enriched fuel for more than 2-3 months you may have to clean out the carburetor as it tends to gum up pretty quickly.

[greg g]

Check for debris in the inlet needle and seat.  Doesn't matter where the float is set if it doesn't shut down fuel flow into the bowl because the valve won't close.  Also pull out dipstick, if your oil smells of gas, make sure you do an oil change when you g et the leaking sorted.  There is one more item to check for over rich mixture, but you need to get the first issue felt with first.

[3046moparcoupe]

What Greg G said I added an inline fuel filter on the drivers side, on the outside of the frame rail, tp prevent crap from getting into the needle and seat of the carb.

 

[Hawkhero]

I agree with Greg. Also make sure the float is set based on  the highest point. It also helps to make sure the float actually floats. 

If you remove the air cleaner and look into the carb with throttle wide open (Engine not running) you will probably find the intake full of fuel. Once you fix the reason the fuel is being forced through the carb, the fuel in the intake will resolve itself after a quick drive. 

Had the same issue on my P20 and after dinking with it, adding a regulator, etc, I found the chunk of whatever stuck in the needle. So much time and energy wasted on what I should have checked first. 

--Brian