Help with Quadrajet decoding
Thread Starter
Instructor
Joined: Jul 2016
Posts: 226
Likes: 108
From: Crescent Beach, FL
Help with Quadrajet decoding
The '70 BB I just bought has a non-original Quadrajet that I'm curious about. None of the decoding sites I could find made sense. The number stamped on the body is 7040784. Any ideas?
Never mind. Maybe that's why I've always been a Holley guy. Thanks for the help.
Never mind. Maybe that's why I've always been a Holley guy. Thanks for the help.
Last edited by JohnnyQuik; Jul 15, 2016 at 07:46 PM.
Team Owner
Joined: Sep 2006
Posts: 31,172
Likes: 4,250
From: Westminster Maryland
Hi JQ,
That appears to be a casting number, not a stamped carburetor number. Is what's in your picture on the carb's base plate?
Regards,
Alan
I 'believe' this is the typical location on the Q-Jet for the 7 digit GM part number stamp and date of manufacture.
That appears to be a casting number, not a stamped carburetor number. Is what's in your picture on the carb's base plate?
Regards,
Alan
I 'believe' this is the typical location on the Q-Jet for the 7 digit GM part number stamp and date of manufacture.
Last edited by Alan 71; Jul 15, 2016 at 07:36 PM.
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
There's a flat section on the driver's side of the carburetor behind the secondary throttle linkage that will have a number embossed into it. That's what you need to look up.
EX on 17058204:
EX on 17058204:
Last edited by Shark Racer; Jul 15, 2016 at 06:59 PM.
Le Mans Master
Joined: Sep 2003
Posts: 8,812
Likes: 2,029
From: eastern NC
Based on the number the OP provided, in Cliff Ruggles' book it could be a 1970 model off of a Checker or Marine application with an automatic. If the second #7 is in fact a 2, it would mean a federal application verses a California model carb. (5th digit, typically "1" or "2" denotes if the original application is federal while "4" and "5" denote California applications.)
704 = 1970-1975 applications
0 = 4th digit denotes last numeral of the application year
7? = 5th digit, (see above)
8 = 6th digit typically indicates division application (0,1,2-Chevy; 3-Cadillac; 4-Buick; 5-Olds; 6,7-Pontiac; 8-Checker and Marine).
4 = 7th digit typically indicates transmission usage; even numbers are many times automatic trans applications while odd numbers are manual trans, but this is not always true.
Cliff's book is a terrific tool for working on Rochester Quadrajets and will easily pay for itself the first time you rebuild a Quadrajet while using it.
Good luck... GUSTO
704 = 1970-1975 applications
0 = 4th digit denotes last numeral of the application year
7? = 5th digit, (see above)
8 = 6th digit typically indicates division application (0,1,2-Chevy; 3-Cadillac; 4-Buick; 5-Olds; 6,7-Pontiac; 8-Checker and Marine).
4 = 7th digit typically indicates transmission usage; even numbers are many times automatic trans applications while odd numbers are manual trans, but this is not always true.
Cliff's book is a terrific tool for working on Rochester Quadrajets and will easily pay for itself the first time you rebuild a Quadrajet while using it.
Good luck... GUSTO
Last edited by GUSTO14; Jul 15, 2016 at 09:54 PM.
