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Carb Trouble


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I have tried searching but to no avail.

 

I rebuilt the Carter carb on my 53 B4B with the 218 out of a 51 Plymouth.  It sounds and acts like it is sucking too much air and I cannot figure it out.  The mixture screw is all the way in, it will only run smooth with the choke at 1/2 to 3/4 closed.  If I open the choke all the way it idles real rough for a few seconds until it dies.  If I give it gas while idling with open choke it dies.

 

 I have sprayed the outside of the carb and manifold with starting fluid and it does not change the way it runs at all. Timing is set at tdc, it does have some ticking in the valves, but but not bad.

 

Any ideas?  Tom

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I would say to tear it down and clean it again paying close attention to the idle jet. Look closely at the circuits in the book diagram..the main jet, idle jet, choke and step up all depend on a supply in the main tube as it runs with the choke..the main jet would indicate that is not plugged as the tube has fuel..step up would not show up till acceleration and the idle would be instant when trying to run the engine..the fuel from the choke passage is augmenting the fuel that should be flowing through the idle jet and orifice tube assembly. While in there you should as advised inspect all other parts of the carb for being their and being clean and operative.

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No wipers hooked up yet, and all vac lines secure. I did the rebuild with a kit from NAPA. It was running better, but has gotten worse. I had the screw adjusted out but, it ran better as I turned it in. Now it's bottomed out.  I guess I'll pull it off and take it apart again.

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if it did good at first and got worse..odds are you have foreign matter in the idle jet and oricfice tube, this jet/tube is quite small and easy to plug. Carbs that sat or may have been subjected to water at one time may have aluminum sulfate type breakdown that will continue to break away for a time..this may well be your problem. I would remove the jet and clean the passage real well that feeds the idle jet..if you find white flaky stuff..the carb may be problematic for some time or never get right....

Edited by Plymouthy Adams
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a cautionary tale:  I lost count on how many times I rebuilt the carb on my '48, probably did it every year from when I got the truck roadworthy in '98 all the way to '09.  It idled fine, it was responsive on the road, and fired up quickly in the cold and hot (after years of struggling with hot starts caused by the original battery cables).  The problem I had was when driving down the road it ran fine, but when I'd hit the brakes, the engine would stall; the only way to counter this was to open the throttle to get about 1500 rpm at 'idle' rather than the factory spec of 450.  After being stymied for over a decade as to what was causing all of this, I finally threw down $20 on an old B&B carb on eBay, picked up another rebuild kit, and rebuilt this 'new' carb.  Over three years later, that carb fires right up, idles fine, and operates as required while driving down the road without much of a pucker factor when approaching a stop light.  My best guess is that one of the fuel check valves (them little b-b looking gizmos in the rebuild kit) would get stuck in its passage and choke the fuel supply leading to the main jet; either there was some debris in that passage that I couldn't see to remove, or the passage had eroded from being gummed up from the truck being parked outside for over 20yrs.  Not that you should condemn your carb now, but finding another carb to rebuild may be an option in your future, or at least have an extra carb on the shelf to experiment with when ya get bored :cool:

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I did pull the plugs. I pulled it apart today and cleaned it again. Exactly the same symptoms. I may try to pick up another carb like JBNiel said. It won't hurt to try another and I would have a spare.

I did drive up and down the drive way for the first time today. That was pretty cool.

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I have two, the 2nd a spare. When I rebuilt the one now on the truck, I disassembled it, the submerged it in lacquer thinner for 24 hours. Then i cleaned every port I could find and put air throught every thing I could. New kit and it works great. I put in a high speed rear axle 3:73 so it is very touchy off stop but then works fine and I get 14 MPG at 65 MPH, so I'm not changing anything. Good luke to you. There is always a solution. Maybe your needle valve tip is flat from over tightening. . . .

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I watched those videos today.  I will pull it apart one more time and compair it to the video, just to make sure I did not miss something. 

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I watched those videos today.  I will pull it apart one more time and compair it to the video, just to make sure I did not miss something. 

Please post your solution if you find one. 

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Found the problem!!!   It was the two ports associated with the mixture screw.  Before I took it apart agian I tried adjusting the mixture screw again.  I took the screw all the way out and it did not change the way it ran.  That was a clue! 

 

So i pulled it down again. When I rebuilt it the first time there was a bad spot where the two carb pieces bolt together.  I had to use some sealer to make up for the defect in the mounting surfaces.  Some of the sealant had gotten over the holes and fallen into the ports thus stopping them up.  Thats why the mixture screw had no effect on how it ran.

 

Cleaned it out again, and now it idles.  Runs a little rough at higher RPMs.  I'm sure it dont have it adjusted quite right.  Any Ideas on rough running at higher RPM? 

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There ya' go... sealants in the wrong spot will mess with you every time. ;)

 

For your high RPM issue, try pulling the choke and see if it smooths out. If so you are still lean on the main jet system. If the choke doesn't make much difference, it may be in your distributor. I once made a mistake with points installation and didn't have enough spring tension. This caused points bounce at higher RPM making it run like crap above 2000 RPM, but it idled smooth.

 

Merle

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 Vacuum gauges are cheap and easy to use . When your engine is at idle , adjust that screw for the highest , smoothest vacuum . Other than that you can use the vacuum gauge the same way  to set the timing . Make sure your points are good too and the gap is correct . 

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Check for a vacuum leak. Pull off the vacuum advance line to the distributor and close the port to the carb. See if the problem goes away. 

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I got it running smooth now.

 

I disconnected the vacuum line from the advance and it made no difference. I checked the advance with a vacuum pump, and it moved as it should. I had the vacuum advance hooked up to the port coming off of the back of the manifold, not the carb. So I changed it over to the one coming off of the carb, and capped off the one on the manifold, re-set my points, re-set the timing and started it again.  It idles great, and the acceleration is smooth as well.

 

So it could have been not enough vacuum from the manifold, or my points/timing being off, but I am leaning toward the vacuum.

 

Either way I’m good to go now.

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