No power at 50mph and sooty plugs

[rusty_apache]

Will have help tomorrow setting timing. Hopefully that is the overarching issue here.

 

 

 

 

 Until your timing light arrives, you can find out really quick with a redneck method my Dad showed me. Just advance the distributor until the starter labors and then back off only enough for it to not strain the starter. That is close enough to give you decent power, and you can back off even more if you have pinging upon load when it's up to temp.

 

If that makes no difference you can see if it helps to run the your old condenser. Sometimes brand new ones are defective or can go bad quick.

 

Best of luck.

[Dodgeb4ya]

Timing won't cause black smoke idling and just running down the road.

[Jeff Balazs]

A problem in how the step up circuit inside the carb is functioning surely would.

 

Jeff

[Chrysler49]

Set the timing. Car runs down the road nicely now, but still has a sooty exhaust at idle. Idle isn't perfect, and sounds a bit "burbly."

Still cannot kill the car if I turn the idle mix screw all the way in, and my idle is set about as low as I can get it to go without killing the car.

The step up piston is in good overall shape. I took it out and clean the sleeve out, and the spring seemed to be in good shape. The only possible place that could still be dirty would be the main jet tube. I don't have the special tool to remove and replace that once the rivet is out. My float seems to be a touch on the low side, but I guess my personal observation could be incorrect.

Edited August 2, 2014 by Chrysler49

[Dodgeb4ya]

Sounds like it's good enough.

[Jeff Balazs]

Set the timing. Car runs down the road nicely now, but still has a sooty exhaust at idle. Idle isn't perfect, and sounds a bit "burbly."

Still cannot kill the car if I turn the idle mix screw all the way in, and my idle is set about as low as I can get it to go without killing the car.

The step up piston is in good overall shape. I took it out and clean the sleeve out, and the spring seemed to be in good shape. The only possible place that could still be dirty would be the main jet tube. I don't have the special tool to remove and replace that once the rivet is out. My float seems to be a touch on the low side, but I guess my personal observation could be incorrect.

The main jet should not effect the way it idles. The problem you are having sure sounds as if the step up circuit is involved. Did you check to see if the small passage from the base of the carburetor going up into to the step up piston chamber is clear? A blockage here would render the step up non functional and cause it to run rich all the time. Also another thing could be happening. These carbs are now over 60 years old and the fit of this piston in the bore may be a bit sloppy. The way it is supposed to work manifold vacuum at idle should draw this piston all the way down effectively shutting the step up circuit off. If the piston is not being drawn all the way down at idle for any reason then it is going to run rich. The fact that your idle mixture screw has little effect would indicate that the engine is getting fuel from somewhere else.......and that almost has to be the step up circuit.

Hth;

Jeff

[Chrysler49]

I've got the gasket at the bottom of the step up piston chamber, but should there be some sort of gasket around the piston itself. The slots almost seem like they could hold an oring.

[Niel Hoback]

No rings on the piston. 

[Jeff Balazs]

This is one of those items that can be more than a bit fussy to get working. I can't tell you how many times I had my carb apart. There is not an easy way to test this that I could find other than to refit and try again. You can't see the step up to determine if it is working properly once it is installed. It sure gave me fits and I still think it could be better.

All I can tell you is to make sure it is getting the vacuum signal and keep trying until you get it right. You will be able to tell when it is as the sooty condition will go away.....and the idle mixture screw will have more of an effect. Once you solve it you should consider doing an oil change as the excess gas has probably diluted the oil.

 

Jeff

[Niel Hoback]

   Ok, here's how you take the guesswork out of the power piston.  I start by saying that I've done this a lot, even recently.

   Warm up the engine so that It will start easily. Remove the bowl cover from the carb. Four screws and the choke link.  There is a small hole on the top of the carb body right over the vacuum passage for the idle mixture. It is also taps into the passage for the power piston.  Put a toothpick in the hole of use a piece of tape over the hole.  Go start the car without using the accelerator pedal. You can watch the carb while its running and see if the piston is down on its seat. You can even pull it up if you want to see if it sucks back down. Don't race the engine or the gas will fly. As it idles the needle only drops a tiny bit so it won't have much flow at all.  No, I have never had a fire.

   Don't forget to open the vacuum passage hole before you put the top back on.

  Watch the holes in the side of the venture for slobbering gas. If it does, you may have faulty check balls in you pump circuit.

[Chrysler49]

Car will start and stumble for a few seconds, but won't run without the cover and toothpick/tape over vacuum hole

[Niel Hoback]

Turn the idle speed screw in 1/2 turn until it keeps running. Try not to goose it too hard.

[T120]

Gee!..., I hate to suggest this - but have you  watched Mikes BB carb rebuild on "youtube" ?

[Chrysler49]

Watched that last year when I did my rebuild. I'm pretty sure that's where I ordered my kit from.

[Tom Skinner]

Compression Test First. Gap Plugs. Set Points next. Check Dwell. Set Timing.Check Vacumn - set to highest reading in inches - say 18"-21"(You need a steady hand here or something is wrong such as a vacumn leak etc).

Messing with the Carb continually isn't getting you anywhere.

If the Idle Mixture Needle is Dull at the point - It don't matter which way you turn it - fuel is just dumping into the engine

with no venturi effect whatsoever.

If you need help from an older mechanic GET IT. All this advice is just running you in circles. Use the proper proceedure order above.

I would think your timing is off - thus the missing and sooty plugs (It is most likely Retarded) Setting the timing about 4-7 Degrees in advance to allow for 87% octane gas.

Gas used to be 75 - 78% octane back in the 40's So setting it by the book really doesn't get it anymore. 

Good Luck.

Tom

[T120]

Sorry, Didn't want to appear as an authority.Hope you find your problem,at this point - I would guess carburation

[Tom Skinner]

Ralph,

I too don't want to sound like an authority. It may be the Carb. (Clogged needle and seat or otherwise worn Idle Mixture needle (Check point of needle) it should be relatively pointy not rounded)

Question: have you checked the tension on the points after setting them?

They should be about 18-19 oz (Use a small had held scale) I have set mine to loose and sometimes this causes sluggish performance @ 50mph.

Also Compression is Good if consistently across the Cylinders (example all about 90 Lbs, or 95 Lbs) above 100 is desirable. I have had an old Chrysler back in the day that had 85 - 95 LBS

that was worn (Rings) that ran fine  because the Cylinders didn't differ by more than 10 LBS from one another. These old Flat Heads can flood fast with dirty/worn needle and seats etc. The tolerances where not as big a deal then and with wear these beasts like to burn gas and oil (as well as leak them) LOL

 

Good Luck again!

Tom

[BigDaddyO]

You never mentioned any RPM readings.

What does it idle at?

[Chrysler49]

Don't have a tach, so cannot be 100%. I aim for a low, but smooth idle. 450 is what the manual wants.

[Dodgeb4ya]

Absolutely no authority here but...... EVEN more information thats probably no good!

 

I hope your Carter carb # is correct for your car.

 

For improper idle operation check idle vent hole in air horn, .0531" Dia. for 1949 model C45 chrysler six. Main body hole oriface directly under air horn idle hole must be clear and not obstructed.

 

Some more pictures...Carter Carb book 1949 Chrysler Parts list and tech info....

Edited October 21, 2017 by Dodgeb4ya

[Jeff Balazs]

   Ok, here's how you take the guesswork out of the power piston.  I start by saying that I've done this a lot, even recently.

   Warm up the engine so that It will start easily. Remove the bowl cover from the carb. Four screws and the choke link.  There is a small hole on the top of the carb body right over the vacuum passage for the idle mixture. It is also taps into the passage for the power piston.  Put a toothpick in the hole of use a piece of tape over the hole.  Go start the car without using the accelerator pedal. You can watch the carb while its running and see if the piston is down on its seat. You can even pull it up if you want to see if it sucks back down. Don't race the engine or the gas will fly. As it idles the needle only drops a tiny bit so it won't have much flow at all.  No, I have never had a fire.

   Don't forget to open the vacuum passage hole before you put the top back on.

  Watch the holes in the side of the venture for slobbering gas. If it does, you may have faulty check balls in you pump circuit.

You have much bigger stones than I. Honestly I would rather fumble along blind than try this. Could get ugly real quick.

Jeff

[Dodgeb4ya]

I have run an engine with the top off a few times too. But would not advise anyone to try this as a lawsuit could result in my demise

[BigDaddyO]

How did it run before this happened?

Before you worked on the distributor?

[YukonJack]

How did it run before this happened?

Before you worked on the distributor?

Good point BigDaddyO. The first post said car ran fine until the distributor rebuild. So why are you faulting the carb? My guess is the problem is ignition. Maybe if the plugs are black and sooty they need to be replaced or at least cleaned and regapped. 

[Niel Hoback]

Black plugs can be caused by a weak spark. Check that dwell again.