carburetor codes

[jasonw]

HELP ON YEARS      CAN'T FIND IN BOOK


ROCHESTER QUADRAJET 17057020
QUADRAJET 7028212

[lakeholme]

17057020 = Won't be in "the book", because it's a post 1975 carb. But look on page 154.  The 170 prefix started in 76.

7028212 = 1968 MV used in Camaro with 327/275HP A/T or 350/295HP A/T and in several other Chevy applications.

[bertfam]

Try THIS SITE for Rochester carb decoding.

Ed

[My68SS]

I have a curiosity with my 12C 1968 L34 auto carb numbers - 7037931
These are cast into the rear of the body in a circular shape.
The first 4 digits are fine, but the next digit [9] doesn't add up to the details on oldengine.org
Should be in the range 0 - 5  I've rechecked it under a magnifying glass from all different angles and it's definitely a 9

The 2nd last digit [3] is also odd - Cadillac division?? and the last digit is for manual, not auto.
Am I looking at the right numbers on this carb? I can't find any others anywhere on it.

[My68SS]

These guys http://www.recarbco.com/technical/rochester/qjet.html suggest that Rochester didn't always follow the rules with regard to the last few digits.
At this site  http://www.holisticpage.com/camaro/parts/carb.htm there are some more id locations mentioned.
Maybe mine had the tag under a airhorn screw? I can remember seeing one of those, can't remember which carby though.
Hopefully I have a carby of the right year for this car at least...

[My68SS]

Hopefully I have a carby of the right year for this car at least...

I still might not even have that right!
So far I have been assuming that because my model 68 was built in 1967, the carby would have a 70x7xxx code, but everywhere I read, the code is quoted as 70x8xxx
Is that correct, mine should be 7028xxx or 7038xxx?

Also, for 60's carbys, there seems to be a necessary relationship between the 3rd digit [2 or 3] and the 5th digit?
ie. if the 3rd digit is a 2, then the 5th digit has to be either 0,1 or 2, [2 for q-jet]
if the 3rd digit is a 3, then the 5th has to be either 3,4 or 5. [5 for q-jet]
Have I read that right?

[ccargo]

My 68 L35/M40 has a 7034481 carb on it but I'm not certain its the original. I've tried to decode it but nothing seems to fit past the 703 portion? The smog equiped cars seem to have a little different format.

[My68SS]

ccargo, were on the carby are you finding your numbers, at the rear like mine? Are they stamped or raised cast numbers?

[rich69rs]

If not stamped on the body, then a tag.  Pic is from the 2BBl on my '69 RS

[My68SS]

If not stamped on the body, then a tag.  Pic is from the 2BBl on my '69 RS

Is there any correlation between the cast raised numbers in a circle at the rear and the numbers on the tag?

edit: was the tag under the airhorn screw typical for 1st gen Camaro's?

[rich69rs]

Separate tags, installed under the front middle air horn screw, were fairly common by 1969, at least for the 2 Bbl carbs.  7029110 is the correct 2 Bbl for 1969 Camaro base V8 (327 or 307) with auto tranny, no A/C, and no A.I.R.
Not sure what some of the other numbers cast into the top of the carb mean.  Pic shows the tag / carb perspective better.

Numbers on the tag (7029110; H8; CH) decode as: 
               70 = Prefix Code; Rochester
                2  = Decade Produced; 1960’s w/o A.I.R
                9  = Model Year; 1969
                1  = 2 BBL; Federal Stds.
                1 = GM Division; 0, 1, or 2 = Chevrolet
                0  =Transmission; Even #’s = Auto

               H8 = Month/Year Built = August, 1968
               CH = Factory Inspector on Production Line (not correct - see KurtS comment below)

[KurtS]

CH = Factory Inspector on Production Line

Nope.
CH = broadcast code.

[rich69rs]

Thanks Kurt,

My previous info. on "CH" came from an earlier CRG forum discussion.  Thanks for getting it corrected for me.

Richard

[My68SS]

Ok, this site has some intersting info on various carbs including rochester, though the tag usage seems to differ from your understanding Rich?
http://www.thecarburetorshop.com/Carburetor_ID.htm

I'm a bit more confident now that my carb is the original, especially after reading the bit about the raised casting numbers.
I'm just missing my tag  

[rich69rs]

Very interesting - according to the info at the link, some Rochester carbs had tags going back to 1949.  It would be interesting to know what was the differentator that Rochester used to determine when the part number physically got stamped on the carb vs. when it was on a removable tag.