Back fire after engine shut off.

[OUTFXD]

Started after I rebuilt the carb a couple months ago.  I did a rebuild and soaked it in a dip tank over night.

 

After the "rebuild" I have had numerous issues.  The gaskets didnt line up correctly resulting in numerous vacuum leaks. I managed to cross thread a bronze vacuum fitting, resulting in a vacuum leak and destroying a bronze fitting with two seperate thread pitches (That was a pain to replace).  Chasing odd throttle response I found the Accell pump jet was plugged...

 

When the engine is hot it is hard to start,  generally acting fuel starved.

 

Lately she has been requiring about 20% choke to run smooth.  I have been blaming the hot weather but now I am not sure.

 

every now and then.  she backfires through the exhaust like 3 to 4 seconds AFTER the engine has been shut off.

 

I am considering tearing the carb down again and giving it a real good going over.

 

Suggestions on things I should be paying attention to?

Edited August 17, 2022 by OUTFXD

[desoto1939]

When you took the carb apart and I am assuming that you have a Ball&Ball carb did you put the small ball bearing back in the incorrect holes.  These two small BB's look to be the same size but are different. Did you soak the accelerator pump leather in light oil to soften up the leather.

 

If you rebuild the carb suggest that you get several cardboard egg cartoons and then number each hole. As you take apart the car but each part in the appropriate numbered hole. This way you just go backwards to re assemble the carb.

 

Do you have a Sisson choke on the car and has it been setup correctly. I have lots of info on these sisson chokes.

 

Rich HArtung

Desoto1939@aol.com

[OUTFXD]

It is a Carter B&B1.   I watched a video on rebuilding it.  I do recall the guy stressing which ball goes where. The accell pump was replaced.

 

I am not sure if the choke is Sisson or not.  How wold I tell?

 

Thank you for the advice!

[Doug&Deb]

The Sisson choke is mounted on the intake manifold. A wire comes from the starter. I suggest rebuilding the carb again preferably with a different kit than the one you had problems with. I’ve had good luck with kits from Daytona. It sounds like your problem started after the rebuild so starting from scratch is a good thing.

[capt den]

this is why i pay more than i would like to pay to have a carb rebuild done by the experts. although these carbs are considered simple by many, they are more complicated than many people, including myself, really know how to properly deal with. although i do alot of the work on my car myself, i send out things like the carb, generator, starter motor and heater blower motor to be rebuilt by others. i am amazed by the people on this site who have the knowledge to do so many things. i am glad to use that sometimes and to add what knowledge i have. can"t help with the carb though.    capt den

[Tom Skinner]

Old School Rule of Thumb:

Backfiring out of Tailpipe is too rich a setting.

Backfiring out of the Carb is too lean a setting

Is your Choke set correctly?

 

[greg g]

Buy a vacuum gauge, learn how to use,read and interpret what it shows you.  Enriching the mixture by running the choke is a sign of a vacuum lead on the engine side of the throttle butterfly.  Start by checking the butterfly pivots if they are worn, they can cause lean running condition.   Use an unlit propane torch Crack the valve and point the flow toward suspected places,  check all the areas where there are places where air can enter the engine below the carb.  Do this with engine at idle.  If the idle speed increases or the engine smooths out while the torch passes by a leak, thar indicates a vacuum leak.

[wagoneer]

Locate an authentic carter rebuild kit - they are out there; I got one for pretty reasonable $40. 
 

after rebuilding mine, I’ve used two different kits - Mikes Carb and the Carburettor shop . 
 

you start realising that not all rebuild kits are the same and parts aren’t included in all.

 

aso it’s soooo easy to put it back together incorrectly. The accelerator pump adjustment is a pain and I had/have trouble with it not properly squirting enough out of the priming  jets.

 

mikes over the carb shop but I’m looking for better new ones if they exist. Seems like most are reselling same bits and pieces. My carter one has pieces none of the rebuild kits have.

 

Read the official instructions and there are good ones here on this site in the tech library from carter, they really work and make sense after you look at it and rebuild it a bunch.

 

 

Edited August 18, 2022 by wagoneer