Model B Carb issues

[TDO]

I also run a model B carb. that I rebuilt with Renners flow tested jets. Mine runs great. Un like the A model I never use the GAV just leave it closed. I did put in the stainless steel power jet tubes I bought from e-bay.

[KMeredith87]

I trust renners and y he carb that I got running had their jets in it but it won't run once a load is out on it. I also have the stainless power tube but I did not install it as the brass one seems fine currently.

Sparky, I actually check the Ford garage before starting this thread. Lots of info about the carb but not a whole lot about rebuild that I saw. I keep fiddling with it and hopefully get it figured out.

[Brian T]

Originally Posted by KMeredith87

I have two model B carbs that's I have recently rebuilt but don't run. The castings were thoroughly cleaned out and inspected prior to painting. One has an original numbered set of jets while the other has a flow checked set from renners in it. Both seam to seal fine and don't leak fuel but won't run. The truck runs fantastic and starts with no issues with my zenith 1 on it. This is my first experience with model B carbs and am not sure what's up. Any thoughts? I'm a bit stumped...

Seems odd that you have 2 B carbs with the same problem, the symptoms act as if the float valve is stuck shut, run a while then stop, pulling the choke it may attempt to run.

It is my understanding the only float valve available for a B carb is the Grose jet (ball valve) noted for sticking closed when the engine is not running, we used them in the 70s to cure flooding on import cars with opposite results.

My truck runs very well with the B carb, however I have had to unstick the valve a few times, my worst experience was having the problem occur while driving, I posted here asking if there was a conventional valve available, Renners say that is all that's available.

I did replace it but later the same symptoms occurred, so I ask again is there a standard type needle float valve available that fits the B carb, if someone has one used or otherwise please PM, hope this will help with the above post.

[KMeredith87]

I'm fighting through the problems....got it to run and drive but once I hit 50-52ish it bogs down pretty bad and wants to stall and idles a little strange. On the up side the engine seems to run smoother with this carb just need to get it running right.

As for the float valve...I have an original brass seat and needle similar to the A's. I took it apart and cleaned and polished the needle and seat together using baking soda and toothpaste as suggested on other post in the past. This method worked well for me and seals well. Also, I've definitely not ruled out myself being part of the cause seeing as you said I have two that seem to being doing the same thing. I've rebuilt carbs in the past and haven't had a problem but the B carb is new to me. Getting to the point that I'm half tempted to send it to renners and let them fix it for me!

[c. sefton]

Are you using different fuel lines from "a" carb to "b" carb set up? Maybe your "b" fuel line is going to far into "b" carb, restricting flow.

[afuncar]

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I tried a B carb on my A, every corner it would stall no matter what I tried, thought I checked everything no better. Finally found the problem, the float was leaking!

[tiger.1000]

Meredith,

Out of interest, what procedure are you using to start from cold? Model B carbs have in the past driven me nuts !

On my 32 Model B to start from cold I pull the choke out and turn the choke anti-clockwise about 2 full turns for cold start. This opens the GAV. Once started I then turn the choke cable clock-wise leaving it open about 1/2 turn . I find that if I try to drive with the GAV closed the car is reluctant to accelerate smoothly.

Reams have been written on this subject and it seems no two B carbs are the same and no two Model B cars have the same starting/driving procedure.

After a close encounter with the shrink I sent mine to Dave Renner. He is the man.

[KMeredith87]

Tiger,
I've honestly tried about every different starting method with them to get it to run right and no real luck one way or another. With the zenith 1 installed the truck will start up on typical day on a cold motor with no choke with in about 10 seconds or so...I think I will have to pick up a model B carb book and see what it has to say and if worst comes to be I'll send it in to renners!

[tiger.1000]

Meredith,

Send me a PM including your email address and I will forward you an email that Dave Renner sent me. It includes two diagrams; one showing an exploded section of the B Zenith together with the procedure for checking all of the jets and passageways.

In the meantime if I can work out how to post them on the thread I will do that but I am computer ILLITERATE !

!

[tiger.1000]

Meredith,

Hope you can read this? Dave Renner's procedure for testing B Zenith.

Good luck !

[Purdy Swoft]

tiger 1000 is correct. I have run and rebuilt my own model B carbs for years. You do need to open up the GAV for cold starts or they will hesitate and quit. Try opening the GAV untill it will take the gas without hesitation. It only takes a brief warm up. when the engine begins to lope, reach over and close the GAV and you should be good to go. I use original jets and have never needed to remove a passage plug. A small wire carburetor cleaner and compressed air has always worked for me. I buy swap meet carbs and do my own.

[KMeredith87]

Thank for the info tiger! And purdy that's my goal eventually to run dual Bs like you have but have issues with just one right now. I was able to get it to idle well and once driven a mile or so the idle became rough and acted like it wanted to die then would bog down badly around 45-50 or so. Definitely want to be able to do my own as unforunately the availability of people who can do it for you is slowly decreasing...

[tiger.1000]

Meredith.....here's a silly question.....have you checked your condenser ? They can play up when warm and create mis-fires and then die on you , then come back to life when cold.

[KMeredith87]

I'm actually running one of bubba's ignition centrifugal advance Mallory's...no problems with the distributor as I just installed it a couple weeks ago (fantastic distributor for those who are curious) and also the truck with run just fine with my zenith one on it and can and will whit 65-70...

[Marshall V. Daut]

I just got a Model B carb working correctly the other day that I hadn't run in 15 years. All passages were clear and everything checked out before mounting it on a friend's car. Yet, on occasion and not every time, the engine would start to sputter, idle poorly and then gas would start coming out of the throat. I lowered the float some and changed needle & seats, but still the intermittent problem existed. The float had two small solder repairs, but based on its use for 10 years prior to going into storage, I felt the float was o.k. However, after disassembly and fooling around with the carb for about the 100th time, I shook the float and sure enough! There was gas inside. Apparently another small leak had developed and gas was getting inside the float, but not completely filling it. What was happening was when I disassembled the carb and laid parts on the ground, gas must have dribbled back out of the float so that it would operate o.k. for a while before just enough gas seeped in to cause it to sink. That caused the misfiring and eventual gas running out. Disassembling the carb each time, who would notice gas dribbling out of the float amid all the gas on the ground from the bowl? Anyway, a new float from Renner's Corner solved the problem and the engine runs great.
I know you said your float was good, but check it again. They are so light-weight that even with some gas inside, it's hard to tell for sure unless you shake it and listen for sloshing inside.
Model B carbs are GREAT when dialed in, as they all can be if proper rebuilding procedures and CORRECT parts are used. Installing a rebuild kit is only the first step. Each jet must be checked for size and length. These kits are made of parts that are close, but not exactly correct for Model A and B Zenith carbs. They often come from tractor carb kits. Unless the jets have been flow-checked and the lengths measured, its a cr*ps shoot if the carb will function properly. Don't give up on these B carbs yet! They CAN be made to work the way they were designed.
By the way, to get around the carb being mounted at an angle on the bored-out Model A carb, I ground the shafts of the mounting bolts in the area where they go through the intake manifold flange. That allowed the carb to be rotated enough to line up nicely with the choke rod = no more binding. This method costs nothing and does not compromise the integrity of the mounting bolts. There's still plenty of meat left on the shanks to hold a one pound carb!
Marshall

[KMeredith87]

Marshall, I will check my float again as who knows what has happened. When I checked it initially I kept it submerged in water for a couple days and then submerged in cleaner for a couple more and found no leaks and always came right back to the top of whatever it was in. As for my jets...they are all proper jets flow check by renners though I do also have an original set that I am not currently using. When I have it on the truck and running it seems to have the truck running smoother, that is until all hell breaks loose anyway!

[Tom Wesenberg]

Shake the float to see if it has any gas inside. If not, then dip it in hot water and any pin holes will show bubbles right away.

[KMeredith87]

I double checked the float today...didn't hear any fuel inside of it so I brought inside and put in hot water as Tom suggested and no leaks. Almost wish there was at this point...does anyone know exactly what the float high should be at on a B carb? Right now I just have it set similar to how I would a zenith one and just ensured the float seals the seat closed when completely vertical...

[jim1932]

I am no expert, but can you post a photo of the carb opened up? I had one I forgot to put a power tube back in.... since oyu did both of them maybe there is a mistake someone can spot.

[KMeredith87]

I'm up for anything at this point. Don't have the best pictures at the moment but here is one I took yesterday when speaking with someone else about it. There is no spring on the float, new flow tested jets, no leaks in the float, all passages clear as per Renners instructions, new power tube. Think that about covers everything...