Rochester Quadrajet ID issue - The 1947 - Present Chevrolet & GMC Truck Message Board Network

czarcaustic · 09-28-2009, 11:55 AM

Hey guys ... my carb is spewing gas all over the place so I have decided to rebuild the ol' quadrajet.

I grabbed the stamp and then went online to ID my specific carb but something has confused me.

Stamp says:

7046216 YD

I understand:

70= Rochester
46= ???
2= 49 state emission
1= chevy
6= auto tranny
YD= ??

The questions:

Everywhere I check 46 is not an option, it SHOULD stand for 1976, however this engine (and I assume carb) is off of a 1980 chevy pickup (PO swapped the ol inline 6 for the 350/350). Furthermore it seems that rochester went to the 170 prefix in '76 and I don't have a 170 prefix. Is this something anyone else has run into?

What is the YD?

Any help from the all knowing would be greatly appreciated!

Czar Out!

Jim_PA · 09-28-2009, 12:48 PM

Check the casting again? Got any pics of the carb?

czarcaustic · 09-28-2009, 01:43 PM

I guess I need to go back over to the barn and recheck that casting number - it just doesn't make sense.

Pictures:
http://picasaweb.google.com/tuszynsk...at88b9p7DFtgE#

Jim_PA · 09-28-2009, 02:35 PM

Just for fun, I'm going to say it's a 1971.

The choke is pre-74, and the idle mixture screws would have been plugged from the factory if it was 72 or newer. Not to say that someone couldn't have changed that...

I also think the vent on the front of the carb was different in years 1970 and older.

fleetimus · 09-28-2009, 05:23 PM

http://www.carburetion.com/quadnumber.htm

**DANTIP** · 09-28-2009, 05:43 PM

The last two characters on my Q-Jet carb stamp is IU (likely in the same place as your YD) and in the carb section of my build sheet is IU, therefore I assume this was the code used at the factory. I have never seen a breakdown of this 2-letter code.

**yote1234** · 07-24-2013, 02:08 PM

Quote:

Originally Posted by DANTIP

The last two characters on my Q-Jet carb stamp is IU (likely in the same place as your YD) and in the carb section of my build sheet is IU, therefore I assume this was the code used at the factory. I have never seen a breakdown of this 2-letter code.

mine is a IU as well. anyone know?

09-28-2009, 11:55 AM	#1
czarcaustic Registered User Join Date: Aug 2009 Location: Panama City, FL Posts: 84	Rochester Quadrajet ID issue Hey guys ... my carb is spewing gas all over the place so I have decided to rebuild the ol' quadrajet. I grabbed the stamp and then went online to ID my specific carb but something has confused me. Stamp says: 7046216 YD I understand: 70= Rochester 46= ??? 2= 49 state emission 1= chevy 6= auto tranny YD= ?? The questions: Everywhere I check 46 is not an option, it SHOULD stand for 1976, however this engine (and I assume carb) is off of a 1980 chevy pickup (PO swapped the ol inline 6 for the 350/350). Furthermore it seems that rochester went to the 170 prefix in '76 and I don't have a 170 prefix. Is this something anyone else has run into? What is the YD? Any help from the all knowing would be greatly appreciated! Czar Out! __________________ ------------------------------- '71 GMC 1500 Longbed (Marilyn: PICS) '04 Toyota Tacoma (grocery getter) '03 Lexus ES 300 (Wife's) ------------------------------- '72 GMC Short Fleet (Sold - offer I couldn't refuse)

09-28-2009, 12:48 PM	#2
Jim_PA Registered User Join Date: May 2005 Location: PA Posts: 2,696	Re: Rochester Quadrajet ID issue Check the casting again? Got any pics of the carb?

09-28-2009, 01:43 PM	#3
czarcaustic Registered User Join Date: Aug 2009 Location: Panama City, FL Posts: 84	Re: Rochester Quadrajet ID issue I guess I need to go back over to the barn and recheck that casting number - it just doesn't make sense. Pictures: http://picasaweb.google.com/tuszynsk...at88b9p7DFtgE# __________________ ------------------------------- '71 GMC 1500 Longbed (Marilyn: PICS) '04 Toyota Tacoma (grocery getter) '03 Lexus ES 300 (Wife's) ------------------------------- '72 GMC Short Fleet (Sold - offer I couldn't refuse) Last edited by czarcaustic; 09-28-2009 at 01:55 PM. Reason: added pictures

09-28-2009, 02:35 PM	#4
Jim_PA Registered User Join Date: May 2005 Location: PA Posts: 2,696	Re: Rochester Quadrajet ID issue Just for fun, I'm going to say it's a 1971. The choke is pre-74, and the idle mixture screws would have been plugged from the factory if it was 72 or newer. Not to say that someone couldn't have changed that... I also think the vent on the front of the carb was different in years 1970 and older.

09-28-2009, 05:23 PM	#5
fleetimus Registered User Join Date: Jul 2000 Location: Auburn,Ca USA Posts: 369	Re: Rochester Quadrajet ID issue http://www.carburetion.com/quadnumber.htm __________________ 68 Chevy l/b, 4 whl disc in the foothills of No Calif

09-28-2009, 05:43 PM	#6
DANTIP Registered User Join Date: Sep 2001 Location: Fort Wayne, Indiana, USA Posts: 1,890	Re: Rochester Quadrajet ID issue The last two characters on my Q-Jet carb stamp is IU (likely in the same place as your YD) and in the carb section of my build sheet is IU, therefore I assume this was the code used at the factory. I have never seen a breakdown of this 2-letter code.

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