I bought a Q-Jet with two numbers in it, the first and I think is the original is
7029207
70-Prefix code
2 -decade produced
9 - year...1969
2 - 4 bbl Federal
0 - Chevy
7 - manual tranny
with a date code of
2836
but then there is another number stamped into it
7040502, which I think someone stamped into it and I bought it on Ebay for these numbers for my 1970 automatic with a 350/300 hp car, did I get the wrong one? I know the second set of numbers is correct for my car. Also what would the date be..2836 (283rd day of 1966?)
70 -Prefix
4 -decade produced 1970-1975
0 -1970
5 -4 bbl calif
0 -chevy
2 - automatic

 

The 7029207 is the 69 version of my 70 L-46 7040207.

For some reason the 7029207 was the workhorse and was continued to be produced for quite some time. It was later replaced with another number I don't recall. The "6" in your date code could easily be 1976

Don't know the differences in the calif Q-jets over the rest. I do believe they had the heat shield under them though

 

"Restamped" Q-Jets are becoming pretty common. People take a Q-Jet, slap some other jets in it, and re-stamp the number for the new jetting combo. You need to determine which stamping is the original and which is the re-stamp. The re-stamp means nothing - it's the original stamping that the carb should be set up for.

Carb 7029207 is a 1969 Vette carb for a 350 325-horse. It was jetted with 66 jets, 36 primary rods, and "BG" secondary rods.

Carb 7040502 is a 1970 350 Chevelle/Camaro carb for a California application. It was jetted 76/44/BA.

As you can see, the jetting on the two carbs is vastly different, and internal air bleed calibrations are different to match this different jetting. Simply swapping jetting confuguration between the two carbs does not work well.

As a visual indication, you can tell a 1969 carb because it has the idle vent system on the forward top area of the carb. 1970 does not have this. I have seen, however, some '68/'69 carbs with the idle vent converted to post-70 configuration by installing a stamped steel plug in the idle vent port. If your carb has a plug in the idle vent or the idle vent system intact, it's a '69. If the idle vent hole is cast closed (never been there), it's a post-70.

 

my 70 -350hp, 7040207 ,has the idle vent valve. (june build)

 

I am thankful for all the help Lars and others has helped me out in this forum, and I think it is a 1976, but then the numbers and the date code dont make sense (date code of 2836 vs 7029207, dated the 283rd day of 1966 or 1976 where the 2 of 7029207 was produced in the 1960s, if I am reading this right) I think I found where the idle vent is cast "closed" and this was restamped as the restamped numbers are off to one side, but I had it rebuilt before I knew this by Bob at Competiton Carbs and he does excellent work here in the Sparks-Reno area of Nevada, so lesson learned and again thank you for everyones help in this matter.

 

I don't think they made a Quadrajet in 1966. I think they started making them in 68 model year for Corvettes.

 

PM lars and get his Q-jet papers