Carburetor question-1929 Model 135

[Jrbrks]

I installed a Carter BB-1 updraft carburetor on my 1929 Model 135.

Adjusting the idle mixture screw completely in and completely out has essentially no effect on the engine idle or the engine vacuum (engine vacuum gauge needle is stable at between 15 and 16 psi).

Accelerating and decelerating the engine results in changes in the vacuum reading, as would be expected.

If I completely remove the idle mixture screw, the engine vacuum drops and the engine stalls.

I purchased the carburetor as a rebuilt unit from a vendor in Ohio, and this was the model recommended on the Franklin website, as the correct Stromberg is virtually impossible to find (I do have the original Stromberg, but it has the pot metal body and is, thus, unusable).

Thank you for any guidance or advice. A lead for the correct carburetor would also be welcomed, but I have all but given up on finding one and it seems the Carter should work.

Jim

[laytongarage]

hi, doug in nj. give me a call on problem 201 230 3300

[Guest cehiley]

Hi Doug, How about sharing your thoughts with us on the Forum? I had a BB1 on my Series 12B that exhibited the same problem. Now that I have the car restored I actually have a Stromberg U-2 on it that acts similarly. As received from the carb rebuilder the U-2 at idle makes it lope like its rich and turning the idle air bleed screw in either direction doesn't change much and, if anything at all, makes it somewhat worse. Also the screw was only about 1/2 turn from being closed.

[carbking]

Carter produced 69 different type BB-1 updraft carburetors. Simply saying "BB-1" is similar to saying "15 inch tire".

Of those, ONLY the BB-1A and BB-1D should be used on the Franklin.

Possible idle issues as posted above IF CARBURETOR RELATED would include:

(1) Incorrect BB-1

(2) Too much fuel pressure or incorrect float adjustment

(3) The hidden idle jet was not removed and cleaned by the rebuilder, or the passage has a clog

(4) Incorrect adjustment of the curb idle screw (not the mixture screw)

(5) Incorrect adjustment of the fast idle screw

(6) Hopefully not, but throttle valve installed incorrectly in the carburetor (yes, I have seen this numerous times).

(7) Power jet not rebuilt, thus power jet open at all times.

The BB-1 IS a great design, when properly selected for the application, and properly rebuilt.

And other possibilities other than carb exist, the number one other possibility would be a vacuum leak.

Jon.

[Jrbrks]

Carter produced 69 different type BB-1 updraft carburetors. Simply saying "BB-1" is similar to saying "15 inch tire".

Of those, ONLY the BB-1A and BB-1D should be used on the Franklin.

Possible idle issues as posted above IF CARBURETOR RELATED would include:

(1) Incorrect BB-1

(2) Too much fuel pressure or incorrect float adjustment

(3) The hidden idle jet was not removed and cleaned by the rebuilder, or the passage has a clog

(4) Incorrect adjustment of the curb idle screw (not the mixture screw)

(5) Incorrect adjustment of the fast idle screw

(6) Hopefully not, but throttle valve installed incorrectly in the carburetor (yes, I have seen this numerous times).

(7) Power jet not rebuilt, thus power jet open at all times.

The BB-1 IS a great design, when properly selected for the application, and properly rebuilt.

And other possibilities other than carb exist, the number one other possibility would be a vacuum leak.

Jon.

Thank you, Jon. I appreciate your thoughts and advice. I will check the items you suggest.

How might I determine if the carburetor is a BB-1A or BB-1D?

Being new to Franklins and to vehicles of this age, I went with the recommendation on the original Franklin Q&A section of the club website. It listed the BB-1 as the primary viable replacement for the Strombergs, but I found no delineation of the 1A or 1D requirement. Thus, I went by the throat size (attaching to intake manifold) to match that of the pot-metal Stromberg T2 that came with the vehicle.

Thank you, again.

Jim

[carbking]

Jim - other than to state the obvious that the identification is on the tag, there is no easy answer.

If the tag is missing or some unscrupulous individual placed the wrong tag on the carburetor, exact identification REQUIRES disassembly of the carburetor, and comparison of the calibrated internals with the Carter prints.

It is easier to eliminate the carburetor from being a BB-1A or BB-1D than to positively say it is.

The BB-1A has both upper and lower castings which are cast iron.

The BB-1D has a cast iron upper and zinc alloy lower casting.

Both BB-1A and BB-1D have center-to-center mounting bolt spacing of 2 11/16 inches.

Both BB-1A and BB-1D have "universal" throttle shaft (extends on BOTH sides of the carburetor), a fast idle attachment, and an adjustable main metering jet.

However, as the value of the BB-1A and BB-1D is significantly more than the value of the Chevrolet truck 517s (which uses similar castings BUT DIFFERENT INTERNALS), some of the external parts have been reproduced off-shore to make the less expensive carb look like the universals.

Let us hope that you do in fact have either the BB-1A or BB-1D and something else is the issue.

Jon.

Edited February 19, 2015 by carbking (see edit history)

[carbking]

Jim - see new BB-1 thread under "General Discussion" forum.

Jon.

[John_Mereness]

Because I do not know one single person who is successfully driving with a BB-1 in their Franklin that I would even be remotely pleased with its performance (even though they "love" them).

[amxny]

Jim,

I don't know if you are a member of the Franklin Club, but there is a member, Randy Fusco, that is very knowledgeable about carburetors for Franklins. I got a BB1 from him for my 1928 and am very happy with it. It made all the differance in the cars performance.