Fuel Mixture Screw doesn't change the idle.

[Dodgeb4ya]

I would use the original Idle  screw....a longer narrower screw cannot be right.

Also you say the carb base has been swapped out?

Why was it swapped and is it the correct base...is it drilled right for the upper carb bowl bow,l correct size transfer slots etc..

Here is the factory training film link...punch this into google>>>>>>>>>> "Chrysler Master Tech - 1948, Volume 1-10 The Story Of The Carburetor"

[Young Ed]

2 hours ago, 48ply1stcar said:

While doing my latest carb rebuild I noticed the two things.  New idle/mixture screw is loose, it wiggles a bit.  It's longer than the old one so I probably didn't notice it before and the throttle base was swaped out. ( I'll search for the other and compare) and secondly, Ithink I've been sticking my small ball in the wrong hole.  I have been putting the small ball in the slotted hole under the trottle plunger.  Maybe it belongs in other hole to keep fuel from going back into the bowl. I finally thought of that when the ball fell out of the slotted hole after the retaining spring was installed.  Let me know if I'm right please.

the smaller BB goes under the accelerator pump. If you put the bigger one in there it will get stuck-trust me!

[48ply1stcar]

11 hours ago, Dodgeb4ya said:

I would use the original Idle  screw....a longer narrower screw cannot be right.

Also you say the carb base has been swapped out?

Why was it swapped and is it the correct base...is it drilled right for the upper carb bowl bow,l correct size transfer slots etc..

Here is the factory training film link...punch this into google>>>>>>>>>> "Chrysler Master Tech - 1948, Volume 1-10 The Story Of The Carburetor"

I have a couple of carburetors, and I switched parts and used the parts with the least wear in the throtle shaft area.  I think I can deal with the idle screw.

 

[48ply1stcar]

Ed, there are two passage ways under the accelerator pump, I think I have putting the ball in the wrong passage way.  Now I put the ball in the smaller round hole so that gas can't be pushed back into the bowl.  I'm also going to reask the question on FaceBook.

[Young Ed]

23 hours ago, 48ply1stcar said:

Ed, there are two passage ways under the accelerator pump, I think I have putting the ball in the wrong passage way.  Now I put the ball in the smaller round hole so that gas can't be pushed back into the bowl.  I'm also going to reask the question on FaceBook.

The ball goes in a hole and should be held in place by a c clip. I can't think of what the second hole would be.

[soth122003]

This will help out. The large ball is the discharge check ball and the small one is the intake check ball. The small one goes under the accelerator pump and stops gas from being pushed back into the float bowl and large one goes in the hole next it and has the brass screw plug over it to let fuel flow thru and keep it from being sucked back into the pump chamber when the accelerator pump retracts.

 

Joe Lee

 

[48ply1stcar]

IT"s FIXED, I think.

Last year I removed the glass filter bowl because it was just decoration and served no real purpose.  So I added a desposal filter before the carburetor.  I cut the metal fuel line and used two short rubber fuel lines on either side of the filter.  Because I was running out of small clamps I used the claps that came with the filter.  Not tight enough.  Replaced the clamp and was able to adjust the carb.  Doing the big turn-up up today and I finally bought a real vacuum guage.

I also swapped out the bowl section of the carb with another, didn't clean it.  Someone told me that sometimes it cracks and it's almost impossible to find the crack.

As I stated in post #1 someone used their carb and it ran fine.  I'll return the loose clamp and if it runs find it definetely the float bowl portion of the carb.

 

Edited April 30, 2019 by 48ply1stcar
added info

[JallenChrysler]

Did you find out if it was the bowl? I am having the same issue. I have not been able to solve my problem.

[Pete]

I ran into a similar problem on my '39 Plymouth. The idle mixture screw did not change the idle. In addition it seemed like the engine was running a bit rich.

 

After a lot of trial and error I found the problem. Someone had replaced the idle mixture screw with the wrong part. They used a mixture screw from a 1 1/4 inch bore B&B carb in my 1 1/2 inch bore B&B carb. The screw did not reach in far enough to the port. It was like screwing it all the way in, but in effect it was like it was already a number of turns out. Replaced it with the correct mixture screw and all it well.

 

Pete

 

 

[Dennis Detweiler]

Mine ended as a combination problem. Someone had set the timing way too far retarded. I couldn't find the timing mark on the crank pulley because it was so rusted. Previous owner obviously didn't try to find the mark. I used wet/dry sandpaper, finally found the mark and used typewriter white out to mark it. The engine always idled rough and tuning the carb made no difference. It would idle for a short time and finally chug to a stop. I reset the timing and valve clearance and replaced the original rebuilt carb with a rebuilt Stromberg and it now purrs. 

[harmony]

On 10/6/2018 at 7:10 AM, linus6948 said:

If you want it restored to like-new you can send it to  Dimitrios and he will do it, his work is the best I have ever seen and he is a truly nice guy.

 

http://www.oldcarbrebuild.com/

That link doesn't work?

[JallenChrysler]

I am wondering if the venturi cluster is bad in the bowl section. When I swap out the carburetor it fixes the issue. My problem is that I want the throttle plate from carburetor b (because the shaft is worn causing a vac leak and high idle ect) but the rest from carburetor a. I have orderd a kit to place a bushing in the throttle shaft of carburetor a, that way everything works. However I am still left wondering what is wrong with carburetor b. It has been completely rebuilt, I doubled checked it myself and everything is in order that can I  see. The only thing I can think of is the venturi cluster is bent or clogged or bad is some way that I can't perceive. This could be the reason why when 48ply1stcar swapped the bowl it was fixed. Because the bowl has the venturi. I know my idle screws are correct as I have three carbs with the same ones in all of them and they have very distinct heads. I know the excess fuel is coming from the transfer slots because after running the car with carburetor b and taking it back off I can see where the gas was being supplied from. There are only two places, the transfer slots and idle screws. And I know that the butterfly has been set correctly to show the correct amount of transfer slot. Any ideas are much appreciated. Also my timing was not the issue.

[Sniper]

8 hours ago, JallenChrysler said:

they have very distinct heads.

 

The head of the idle mixture screw isn't what controls idle fuel flow, so it's appearance is not relevant.

 

Length of the screw, length of the taper and the angle of the taper are what matters, you can only see that if you pull the screw out and inspect it.

 

8 hours ago, JallenChrysler said:

I know the excess fuel is coming from the transfer slots

 

Then your throttle blade is too far open.  Either that or your fuel level in the bowl is too high and you are essentially forcing fuel out the transfer slot/idle air bleed/etc.

[harmony]

On 4/22/2019 at 6:02 PM, Dodgeb4ya said:

I would use the original Idle  screw....a longer narrower screw cannot be right.

Also you say the carb base has been swapped out?

Why was it swapped and is it the correct base...is it drilled right for the upper carb bowl bow,l correct size transfer slots etc..

Here is the factory training film link...punch this into google>>>>>>>>>> "Chrysler Master Tech - 1948, Volume 1-10 The Story Of The Carburetor"

Someone needs to give Techy a lozenger 

[Dodgeb4ya]

3 hours ago, harmony said:

Someone needs to give Techy a lozenger 

Mr Tech....He died of throat cancer in the late 60's.

He was a heavy smoker.

[linus6948]

On 3/29/2022 at 10:04 PM, harmony said:

That link doesn't work?

Apparently he has retired from the rebuilding business which is a definite loss to the collector car world. He did museum quality work and he was one heck of a nice guy.