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Carb Tune up and misc


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I recently bought a remarkably stock 1947 Dodge WC truck with the 218.  This is my first post here but I've been lurking the forums for a month or so and what a blessing it has been!  Ok, here goes...I am servicing the Carter BB carb and was wondering if anyone knows the desired vacuum setting for the idle screw.  I was watching an old Mopar service video and it explained some basics about taking care of/how it works and it said for best results use a vacuum gauge to set the idle.  Unfortunately, it didn't give desired readings.  Does anyone have any more information on this?  The truck is from Greeley Colorado and my concern is that it was tuned for mountainous climates.  While cleaning the chassis I had a metering jet fall out from the frame rail!  The truck seems to run fine in MN but I wanted to make sure I have it tuned properly with the right jet.  

 

I have a second question as well but I'll make a second post so as not to get two topics going in one thread.  Thank you in advance!

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Best to keep all your ?? In the same thread then all your answers are in the thread especially if it tune up, driveability related.  Intake vacuum for an engine in good condition should 20/21 inches at around 500 rpm. Keep in mind that ign timing is also a component of the vacuum reading.  As such you can set your timing using the vacuum gauge.  Set the carb first. Then loosen the dist hold down, and move the dist. till the highest steady vacuum reading is  attained.  Then snug the dist. and road test.  If you encounter knock or ping, retard the timing till it disappears.  Your truck will now be set for altitude, fuel,and your right foot.  If idle is high adjust at the carb idle screw,not idle air bleed.

Edited by greg g
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Set the mixture screw for the highest vacuum reading. From there you may need to open it up just a bit to make sure when you set the idle speed screw the throttle plate will be it the proper relationship with the off idle port. If that the relationship is off it can result in a stumble when accelerating from a stop.

 

Pete

 

 

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25 minutes ago, Al Peterson said:

Thanks Pete!  The truck drove fine the first couple weeks I had it but it has slowly developed the stumble from a stop.  Everything seems to be original and well patinaed, it's long overdue for a tune up.  Thanks again.   

 

I had a similar issue due to an inferior set of points. The rubbing block wore down fairly quickly and altered the gap, and timing. It got so bad that I was loosing power and got to be hard starting. Once I figured it out, and replaced the points with a better set, my stumble disappeared and it regained it's power.

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On 7/17/2018 at 3:39 PM, Al Peterson said:

I recently bought a remarkably stock 1947 Dodge WC truck with the 218.  This is my first post here but I've been lurking the forums for a month or so and what a blessing it has been!  Ok, here goes...I am servicing the Carter BB carb and was wondering if anyone knows the desired vacuum setting for the idle screw.  I was watching an old Mopar service video and it explained some basics about taking care of/how it works and it said for best results use a vacuum gauge to set the idle.  Unfortunately, it didn't give desired readings.  Does anyone have any more information on this?  The truck is from Greeley Colorado and my concern is that it was tuned for mountainous climates.  While cleaning the chassis I had a metering jet fall out from the frame rail!  The truck seems to run fine in MN but I wanted to make sure I have it tuned properly with the right jet.  

 

I have a second question as well but I'll make a second post so as not to get two topics going in one thread.  Thank you in advance!

 

For the DTE1-DTE2 main metering jet assembly 224-11S,main metering jet assembly-1size lean 224-17S,main metering jet assembly-2sizes lean 224-18S.

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Thanks Merle.  My truck starts like a dream but I will look into that as well, it was reportedly replaced just before I bought it.    

 

Fernando, 

 

Excellent info.  I am doing the carb this weekend and I'll see what mysteries lurk inside the carb.  My carb number is DTC1, it also has more than one tab punched out on the "razor back".  I have no idea if that's common or not, but I thought it unusual.

 

Thank you to everyone that has responded, what a great community!  

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Make sure you check the freedom of movement of the step up jet.  Located internally, it functions t provide enrichment for power after the initial shot provided by the accelerator pump.  Its default is to be open due to its internal spring.  A manifold vacuum signal holds it closed at high vacuum periods like idle and part throttle cross.  When vacuum drops, when you increase and hold open the throttle, the spring pulls the tapered needle out of the jet.  Make sure when you remount the carb that the slot in the gasket lines up with the small hole in the base of the carb, that is the vacuumvacuum path for the step up circuit. 

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5 hours ago, greg g said:

Make sure you check the freedom of movement of the step up jet.  Located internally, it functions t provide enrichment for power after the initial shot provided by the accelerator pump.  Its default is to be open due to its internal spring.  A manifold vacuum signal holds it closed at high vacuum periods like idle and part throttle cross.  When vacuum drops, when you increase and hold open the throttle, the spring pulls the tapered needle out of the jet.  Make sure when you remount the carb that the slot in the gasket lines up with the small hole in the base of the carb, that is the vacuumvacuum path for the step up circuit. 

greg g,can you explain me what means the last screen?(freedom of movement?).I did not put my B&B E7T2 carb yet.I am running with my brazilian DFV carb similar Zenith type. 

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Carb rebuild complete!  Thank you everyone for your input, it was very much appreciated.  The old carb had been rebuilt at some point and frankly, it was a poor job.  The main reason for the rebuild was to replace gaskets that were weeping way too much.  As it turns out, there was a very specific reason why that was happening and it went unnoticed by me until I went to reassemble it after the overhaul.  The retainer spring for the float is "too tall" despite being correctly seated against the floats pivot point.  I modified it so it sat lower in the correct position only to find out the top portion of the carb had been deformed because of the previous persons rebuild.  The simply tightened the screws down harder, warping the top plate(by the "razor back".  I was able to get it back into place reasonably well.  

 

Bottom line...it runs like a champ and has way more power!

 

Fernando, this is the metering Jet that was in the carb.

 

 

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On 7/22/2018 at 1:42 PM, Al Peterson said:

Carb rebuild complete!  Thank you everyone for your input, it was very much appreciated.  The old carb had been rebuilt at some point and frankly, it was a poor job.  The main reason for the rebuild was to replace gaskets that were weeping way too much.  As it turns out, there was a very specific reason why that was happening and it went unnoticed by me until I went to reassemble it after the overhaul.  The retainer spring for the float is "too tall" despite being correctly seated against the floats pivot point.  I modified it so it sat lower in the correct position only to find out the top portion of the carb had been deformed because of the previous persons rebuild.  The simply tightened the screws down harder, warping the top plate(by the "razor back".  I was able to get it back into place reasonably well.  

 

Bottom line...it runs like a champ and has way more power!

 

Fernando, this is the metering Jet that was in the carb.

 

 

IMG_6336.JPG

On 7/22/2018 at 1:42 PM, Al Peterson said:

Carb rebuild complete!  Thank you everyone for your input, it was very much appreciated.  The old carb had been rebuilt at some point and frankly, it was a poor job.  The main reason for the rebuild was to replace gaskets that were weeping way too much.  As it turns out, there was a very specific reason why that was happening and it went unnoticed by me until I went to reassemble it after the overhaul.  The retainer spring for the float is "too tall" despite being correctly seated against the floats pivot point.  I modified it so it sat lower in the correct position only to find out the top portion of the carb had been deformed because of the previous persons rebuild.  The simply tightened the screws down harder, warping the top plate(by the "razor back".  I was able to get it back into place reasonably well.  

 

Bottom line...it runs like a champ and has way more power!

 

Fernando, this is the metering Jet that was in the carb.

 

 

IMG_6336.JPG

 

Carter B&B Problems & Solutions

Carter B&B, BBR Carburetor Problems & Solutions

Below you will find questions that users have asked about the Rochester 1 barrel carburetor. The questions are followed by our best guess answer. We say best guess, because we don't have the carburetor in front of us and users often leave out important information.
 
Engine Only Runs When Choked
I bought a rebuild kit from you almost a month ago. after rebuilding my Carburetor i can only get the engine to run with the carburetor on full choke. I have tried adjusting the idle set screw, but it does not make a noticeable difference. I watched your video on BBR carbs and followed the instructions carefully. What can i check or do to make it work again?


This is an indication of one of two things.

1 - There is too much air, possibly caused by a vacuum leak.
Using a spray carburetor cleaner (be sure you get the straw that connect to the spray nozzle), spray around the throttle body, both where it mounts and where the throttle body connects to the float bowl. If the RPM changes, then you found a vacuum leak.
Check other possible connections for a vacuum leak. The intake manifold is one of these.
If the problem is new since you did the rebuild, then you could probably concentrate on the carburetor.
Most of the kits have multiple throttle body gaskets and it would be easy to install the wrong gasket. This is a common mistake I have made more than once. Carefully inspect to make sure air isn't being allowed to enter the carburetor at that point.

2 - There isn't enough fuel.
Recheck the float level.
Make sure the needle isn't sticking closed. Cleaning the viton tip with mineral spirits can help with this.
Poor fuel pump pressure could also be the cause. Test the pressure and compare with what is printed in your engine manual. I don't know what is should be and would have to refer to a manual myself.
Look for any restrictions in the fuel line. Where there is rubber line, replace with high quality fuel injection hose. Ethanol will eat the inside of any rubber line.
Did you run thin wire down all passages. Ethanol leaves residue behind that cleaners can't get out.
Gas Leaks Out Throttle Shaft
 
This situation probably indicates that the carburetor is flooding (too much fuel). Excess gas runs down the carburetor throat, hits the throttle valve and runs out the throttle shaft. This does not necessarily indicate that the throttle shaft needs to be bushed. It does indicate that the carburetor is putting out too much gas. Probably dirty and needs cleaning.
Can I get main jets?

Main jets are no longer being produced that we know of.

Your solution to different jet sizes are to drill the existing hole to a larger size, or if you need to reduce the size solder the hole shut and drill out to a smaller size. Not the perfect solution, but does work.
Excessive Fuel in the Bore
 

You are probably flooding (getting too much fuel in the bowl).

 

Test the fuel pump to be sure it isn't putting out too much pressure. Check your motors manual for the specification, but probably around 4 lbs.

 

Make sure the needle & seat has the gasket installed and that it isn't damaged in some way.

 

Make sure the old needle & seat gasket is removed. Any problem with the gasket would allow fuel to flow around the seat.

 

Test the brass float - heat up water and immerse the float. Any bubbles indicates a leak.

 

Make sure the float isn't sticking when moving it up and down. A worn float pin would do this.

The needle may have been damaged when installing. They are easily damaged. With the float up and the needle closed see if you can blow through the needle & seat. Look at the needle to see if there are any marks on the needle.
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