Idle mixture screws identification

[Machmeter1]

Hello, I got me an original Carter carburator BBD 4608S. The carburator looks good so far, but there were two different idle mixture screws in the carburator base. Can someone identify which screw is the right one, or are they both wrong? On Mike's carburator webpage, there are plenty of idle mixture screws displayed for the BBD - not sure what to order.
Thanks Wolfgang

 

[Tinmannz]

I'd say the shorter is correct based upon the description in the links below. However, they both appear to be the same size and probably work, that's why they were together. The guy robbed another carb and pieced them together. its hard to tell if the tips are equal though. Measurements are taken from tip to base of screw head.

CARTER BBD CARBURETOR IDLE MIXTURE SCREW 30A-51 | eBay

CARTER TQ BBD HOLLEY 1940 1945 IDLE MIXTURE SCREW 10-32 1.675" LENGTH 15R-137 | eBay

 

[RustyRatRod]

Match up the long one. They will be easier to access.

 

[AJ/FormS]

Just run them

 

[Machmeter1]

The tips are slightly different. The long screw has a narrower tip.
I put already a lot of time into the rebuild and search for a correct carb. Therefore I am very determined to find the right screws.
Thanks Wolfgang

 

[Dana67Dart]

Here are some photos of idle mixture screws. Notice that they are all square headed.


67 BBD still in the base (CAP Carb which are different than non CAP) ( sorry I don't have a photos of them out but note that they are square headed)

65 BBD (NON CAP)
These measure:
4.78mm (0.188") OD (across the threaded section)
35.32mm (1.391") overall length

(for reference not exact values)
17.25mm (.679") total length of the threaded section (under head of screw to end of threads)
13.48mm (.531") needle section (from thread to tip)
4.59mm (.181) head thickness
3.51mm (0.014")OD at widest part of taper
0.085mm (.033") OD at narrowest part of taper

looks like 32 threads per inch

They appear to be brass

67 AFB (CAP Carb which are different than non CAP)

 

[Machmeter1]

Well, that is good information. Seems like both screws I have are wrong.
Thanks Wolfgang

 

[Dana67Dart]

What year is the carb.

 

[Machmeter1]

Should be year correct for 69 model:

 

[Machmeter1]

I am getting closer, in the carter parts catalog are two idle screws mentioned:
Early production part# 30A 182 (10/32 thd x 1.172L)
Late production part# 30A 198 (10/32 thd x 1.705L)

Since I have a low deck carburator - it should be an early production
Therefore 30A 182 should be the right screw

Problem is, most vendors list just the later production idle screw.