2 Q-Jets what do I have ?

[mtman]

  Hi to all smarter than me, # (1) is 7028267 and # (2) is 7043274 I think #1 is 800cfm and they both need rebuild. I'm no expert on carbs and don't want to mess them up. Any help with what I have and how or where to rebuild them would be great. I need the carb for my Pontiac 400cu.in. with slight build. Thanks Mike 

[Ethan1]

Hi to all smarter than me, # (1) is 7028267 and # (2) is 7043274 I think #1 is 800cfm and they both need rebuild. I'm no expert on carbs and don't want to mess them up. Any help with what I have and how or where to rebuild them would be great. I need the carb for my Pontiac 400cu.in. with slight build. Thanks Mike 

 Welcome to CHP!

 7028267 is off a 1968 Pontiac and Tempest 400cid/428cid, M/T

 7043274 is off a 1973 Pontiac and Tempest, Grand Prix and Firebird 400cid, A/T

 I do not think either of those carburetors are 800CFM, though.

[mtman]

Ethan, Thanks for the info, but I goofed up big time # (1) is #7041540 sorry for the mix up. Thanks Mike

[Ethan1]

Ethan, Thanks for the info, but I goofed up big time # (1) is #7041540 sorry for the mix up. Thanks Mike

 Yes, 7041540 is indeed an 800CFM version off a 1971 Buick Electra and Riviera 455cid, A/T.

[mtman]

  Ethan, Once again Thanks. If the 800cfm is a good fit for my engine I'm going to send it to  Cliff's for a rebuild, and get a kit for the other and try it myself so I have one to run on tell I get the 800 back. I will probably need a little when I cross that bridge  Thanks Mike

[Marx3]

Yes, 7041540 is indeed an 800CFM version off a 1971 Buick Electra and Riviera 455cid, A/T.

say what? I always thought they didn't make the large cfm units untill the M4M came in ´75...?

[Ethan1]

say what? I always thought they didn't make the large cfm units untill the M4M came in ´75...?

 From Cliff's book:

 

In 1971 Buick improved the performance of its large-displacement engines by increasing the airflow capacity of its Quadrajets. Rather than expanding on Pontiac's approach, they simply enlarged the primary bore in the main body. Typically 1 3/32 inches in diameter, Buick's modifications increased bore diameter to 1 7/32 inches. Generally referred to by airflow capacity of "approximately 800 cfm," Buick continued using this design through 1974. Its advantage of additional airflow improved performance, but unlike Pontiac's approach, Buick's Quadrajet retained the velocity boosters for maximum throttle response and improved emissions.

[Marx3]

ohh yes... I read that book so many times, but that part must have slipped my mind :-)

[Ethan1]

ohh yes... I read that book so many times, but that part must have slipped my mind :-)

 Yeah, I forgot it as well and had to look it up in his book.