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Taylormade

BB1 Updraft Rebuild

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I'm rebuilding a Carter BB1 updraft carb for my 1932 Dodge Brothers DL sedan.  The old carb, also a BB1 was slightly different than the one I have now.  I believe it was designed for a Chevy truck and it used to work fine when I drove the car 45 years ago.  I tried to restore it, but the threads in the housing were stripped and there were some corrosion problems, so I bought another carb.  It arrived, with a rebuild kit, cleaned, but not rebuilt as the seller said he won't take responsibility for a rebuild on his part gone wrong.  Anyway, overall the carb seems to be in reasonable shape.  It is also made specifically for The Chrysler Corporation, as stamped on the top housing, so I'm hoping this one will work even better than the last.  The old and new carb below.

 

Carb 1.jpgnew carb.jpg

 

 

 

As I'm going through the rebuild I've come across a couple of minor problems and I need a little help.

 

First is with the Step Up Valve.  When I took this apart to clean it and replace the ball bearing, everything naturally fell out - luckily into the pan I was working over.  I'm pretty sure the reassembly has the ball bearing going in first, then the spring, and then the top cap, but I'd like confirmation to easy my troubled mind.  There was also no new spring in the rebuild kit, just the ball bearing.  Is it okay to use the old spring?  Are replacement springs available?

 

Step up valve.jpg

 

Then the idle passage tube.  The one in the new carb was in rough shape with the top torn up when someone got a little too zealous with a screwdriver in the slot.  I thought I could use the one from the old carb, but since the top casting on that carb is longer, the tube didn't match.  Does anyone have replacement tubes?  I suppose I could turn off the top of the longer tube on my lath, but the shorter tube is so ripped up, I'm not sure of the exact length - or if the length is that important.  Threads on the longer tube seem a bit longer, but it screws in place with no problem.

 

Idle passage Tube.jpg

 

The next puzzle involves the needle and seat.  The new needle and seat I got in the rebuild kit are on top and the old units are on the bottom.  Totally different.  Is this a problem?  Should I use the old parts, or go with the new ones?

 

needle and seat.jpg

 

Next up, the nozzle.  In the picture you can see the black washer that was on the nozzle when I removed it.  I didn't find anything quite like it in the rebuild kit (more on that below.)  I hesitate to use the old washer, but I'm not sure if the correct washer is in the kit.  Since the Carter book mentions that Model 289S uses two gaskets, I assume the thickness of the gasket is important.

 

nozzle.jpg

 

Finally, the matter of the rebuild kit.  I have two, one I bought when I was trying to rebuild the old carb and one that came with the new carb.  Take a look at the gasket sets on this split photo..  Somewhat different, plus I'm sure this is a universal rebuild kit and some of these gaskets don't go with my carb.  But there was no parts list in either kit, so I'm lost.

 

gaskets.jpg

 

Are the three gray washer/gaskets on the far left for the three screws that hold the top to the bottom of the carb?  These did not come with the kit on the right.

 

I can't find anything like the four thin rubber washer/gaskets in the center of both kits.

 

Then the thicker washer/gaskets at the bottom.  The kit on the left has two, the other three.  Can't find a spot for these, either.

 

Of the three red washer/gaskets at the right of each kit, one seems just a bit bigger than the others.  Is this the one for the nozzle?  Any idea what the other two do?

 

Finally, the top two large washer/gaskets seem to be the same as those that cam in the bag with the needle and seat.  Are these extras, or do they go somewhere else?

 

 

Thanks for any information you can provide.  I've gone through the Carter Carburetor Service Procedure Book for the BB Updraft and in their parts group photos they seem to have the washers already on the parts, so it's very difficult to make out what is what.

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OK - will take a stab at this:

 

The power valve - as you surmised, first in is the ball, then the spring, with the jet covering everything. It is not a cap, rather a jet. Note there is an orifice in the center. Different size orifices are used in different carburetors. You can test (to a degree) the spring. Once assembled, the spring should hold the ball closed with the mass of the step-up pushrod resting on the ball. The springs are in the better rebuilding kits. When the engine is in a low vacuum condition, the heavy spring in the top casting under the piston, pushes the pushrod down, opening the ball, and allowing fuel to flow, augmenting the main metering system.

 

The fuel valve - there are at least 12 DIFFERENT fuel valves used in the various BB1 carbs. If you use the new one, reverse the plunger. The flat neopreme goes into the seat. The better kits have the correct valve for the specific carburetor.

 

The idle tube - there are several different. Depending on the tag number of your carburetor, one for your carburetor may or may not be available. The internal orifice differs, as well as the length, from model to model.

 

The fibre washers - as there are dozens of different BB1 carbs, there are a number of gaskets which may be in the kit which will not be used in your carburetor. If you get the generic kit, try to match them up. The better kits have the specific gaskets for your carburetor by tag number.

 

I would suggest you NOT interchange parts from two different carbs; UNLESS you have the Carter bill-of-material for each carburetor and the part numbers are the same.

 

Jon.

Edited by carbking (see edit history)

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Thanks, Jon.  You've  been helping me out since you rebuilt my carb on my 1929 Plymouth Model U.  I know you don't rebuild anymore, but I'll give you a call tomorrow to see if we can find the correct idle tube.  The really bad news is the tag on this carb is missing, so the vital information we need is not readily available.

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Try cleaning the tube with Scotch-brite. It should have the part number stamped somewhere on the outside of the tube. It will be small, so a strong glass, a strong light, and a pair of "young eyes" are essential ;) Wish I still had the last item ;) 

 

If you cannot find the number, chances are your best bet for a new tube would be take the old one to a local machine shop and have one made, as you do have a pattern.

 

Incidentally, there are THIRTY-ONE DIFFERENT BB updraft carburetors made for Chrysler! These include models for Plymouth, Dodge, Dodge Truck, Dodge Truck military, DeSoto, Chrysler, and Chrysler Marine.

 

Jon.

Edited by carbking (see edit history)

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I spent a lot of time with Jon (carbking) on the phone today and he really helped me through some of my problems.  I ordered a part from him, and as soon as it comes in, I'll continue this post and show how I rebuilt the carb.  It turns out there were a few more problems I never saw coming.  i was also relieved when Jon told me this was a very good carb if properly rebuilt and maintained.

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