Re: [Chrysler300] 375 Troubled Horses

["loren nelson" <lorencnelson@xxxxxxxxxxx>]

It sounds like a leaking float needle valve or incorrect float level. I just had the same problem on my G. I think the carbs are similar to the AFB on the G and there are 2 needle valves on each carb. This doubles your chance of a leak. At high RPM the engine consumes the fuel faster than the leak, but at idle the leak adds more fuel than the engine consumes and it floods. 
There could be gas leakage at the base of the offending carb, but with all new gaskets there may not be any leakage. You may have to wait until it stalls and remove the carb tops to see which one has the highest fuel level. The floats should all fall the same distance from the top and when lifted should stop at the same distance from the top. If the floats look good, you have a leaking needle valve. It could just be a piece of dirt in it but you may need to replace the needle and seat. I fixed mine by cleaning them up with some very fine emery cloth but that will not work with the rubber tipped needles. 
Good luck,
Loren in Hotlanta
  ----- Original Message ----- 
  From: keboonstra 
  To: Chrysler300@xxxxxxxxxxxxxxx 
  Sent: Thursday, August 11, 2011 10:21 AM
  Subject: [Chrysler300] 375 Troubled Horses


    
  Would someone who knows a whole lot more than I do about WCFB carburetors try to help me out? The car is a '57 300C.

  Basically what I've got happening on my freshly rebuilt carbs is that I can't get the engine to idle without flooding out. I've tried to follow the book and set the idle mix and air mix screws on both carbs at 1 turn out. Then I followed another expert's advice to put them all at 1-1/2 turns out, and yet another recommendation I heard which said you should close the idle circuit screws on the forward carb completely and set up the idle on only the rear carb.

  I've spent hours tinkering, but no matter what I have done the engine always dies when I let off the throttle below something like 700 rpm. The only way I can then restart the warm engine is to hold the throttle wide open while cranking until the manifold clears after about 20 seconds of grinding. The engine then gradually struggles and coughs back to life. There's so much fuel in the manifold when it dies that I have to keep the the air cleaners on during restarting just to keep flames from licking out of the tops of my carbs. I've learned to keep a towel handy to put the fires out.

  When the above attempts did nothing to help the flooding, I shut down the idle mixture and air mix screws on the front carb, and then tried turning in the rear carb mixture screws until they were all but closed while opening the air mix screw as far as 2-1/2 turns. But no matter what I do the engine always quits and the manifold always loads with fuel. And BTW, I can't blame the fuel octane as I'm using 100LL aviation fuel for the setup.

  I'm pretty green when it comes to carburetor tweaking so I'm really baffled as to where to look next for the solution. Why is it running so rich? The choke plate is wide open with the engine warmed up to operating temp, and yet I have to go wide open on the throttle during the cranking to clear it out before it will run. And even then it doesn't run very well.

  And here's my rant. I REALLY want to hit the road a bit with this car, but it's fighting me every step of the way. I've only gotten to rack up 10 fitful miles so far since the restoration. I've had to track down and fix leaks of every single fluid the car has, even though everything has been rebuilt - gas, engine oil, coolant, brake fluid, transmission oil, PS fluid - along with any other problem you can imagine. It drove me nuts. The only things that haven't leaked are the tires and the battery. So after getting all these issues fixed, I really didn't need a carburetor problem on top of it all.

  Well anyway, where do I look next? Float levels or or incorrect jets or something else? Shall I limp it over to my engine builder who does a lot of carbureted engines - including race engines? They claim to have some "tricks" they know how to perform on the WCFBs. What else can I do?

  HELP !!!!!!!!!!!!!!!!!!!!!!!!

  Thanks.
  Keith Boonstra



  

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