Re: [Chrysler300] 375 Troubled Horses

[Charles Schoendorf <foodfan@xxxxxxxxxxxxx>]

I just put a modified 331 Hemi powered car on the road for the first time.  All I had handy was an old 5lbs. radiator cap and got steady drippage out the overflow tube, especially at idle and always after shutting down.   I went to Napa and all they had were 7 lbs. or 16 lbs. caps that day.  Not wanting to over pressurize the system I chose the 7.  Leakage is much reduced and is now only after shutting down from hot.  I suspect I could go up a tad from 7 and eliminate the problem.  I wonder if what you think is a 14 lbs. cap is really less, or possibly much less.

Chuck


  ----- Original Message ----- 
  From: Keith Boonstra 
  To: loren nelson 
  Cc: Chrysler300@xxxxxxxxxxxxxxx 
  Sent: Tuesday, August 16, 2011 6:12 PM
  Subject: Re: [Chrysler300] 375 Troubled Horses


    
  Several of you suggested that the floats and needle valves were the 
  place to look for the cause. Turns out you were right. One of the 
  float pairs in the primary (rear) carb was incorrectly set by the 
  rebuilder. At least I doubt that shaking in transport could have bent 
  them if they were correctly set to begin with. The bottom line is 
  fixing that float level cured the problem and I thank all of you for 
  your help.

  Here's the next question:
  Why would my radiator boil out the overflow tube after shutting down 
  under certain (not all) conditions? Here's the scenario: Ambient temp 
  about 80 degrees, 20 minute highway ride at 80mph, shut down for 10 
  minutes (no overflow), started and drove low speed for 2 minutes, idled 
  for 5-10 minutes in neutral and shut it down. It boiled out the 
  overflow tube. Registers about 3/4 to the hot mark on the dash gauge

  Everything is fresh - engine, water pump, radiator core, and 14 lb. 
  cap. The thermal fan clutch is not new but worked fine before. 
  Ignition advance is 5 degrees. Is there a way to test the fan clutch 
  for proper performance? Where else could I look for a source of the 
  problem? Radiator cap not actually holding to 14psi? (I will check that).

  Thanks.
  Keith Boonstra

  -
  On 8/11/2011 1:07 PM, loren nelson wrote:
  > 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 <mailto:kboonstra@xxxxxxxxxxxx>
  > *To:* Chrysler300@xxxxxxxxxxxxxxx
  > <mailto: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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