Thermoquad vs Quadrajet

[Jeff Lee]

I need a Q-Jet # 7040263 - 1970 Pontiac 49 state manual trans core. 1970 date, no superseded date code.
Please email direct
JeffLeeAzRealty@qwest.net

[Danny Ashley]

Jeff;
Go to customrebuiltcarbs.com. They're showing 7 in stock. Click on classic carbs, then Pontiac, then follow the charts. Danny

[Jeff Lee]

Thanks, I sent in a request for price quote. I know it's a bendover part, how bad do you think it will be?

[Jim Wahl]

Remember, no matter which carb you choose, the primary and secondaries must be the same size as the original OEM carb. The 1 3/8 primary Thermoquad is actually rated at 750, where the 1 1/2 primary is rated at 800. Jim

[Danny Ashley]

John:
My earlier post was based on your Q-Jet being an 800CFM . I was told by a Mopar guy that Thermoquads came only in 800 and 1000 CFM's but according to Mr. Wahl, there's a 750. That being the case, you could use an Edelbrock #1901 or # 1902. I'd better stick to giving advise just on Q-Jets.LOL. I would check with NHRA to make sure what Quadrajet is legal before spending any money. Danny

[Jeff Lee]

I was under the impression all Q-Jets were 750 CFM except those with only one ring around the booster which were 800 CFM. The 800 was a specialty carb as used on 455 HO Pontiac, SD 455 and probably a few others. Correct or wrong?

On the T-Quad, it's 750, 800 & 1000. Basically small block, big block and motor home big block. Again, correct or wrong? Wasn't there a red bowl race T-Quad @ 1100 or 1200 CFM?

[Danny Ashley]

Jeff:
All Q-Jets were 750CFM (1.093 venturi) until 1971 when the 800's (1.218 venturi) were installed on Buicks. Pontiac got their's in 1973, Olds 1975, and Chevy also 1975. Not sure about Caddy's. The single booster were on Pontiacs in 1971. I have heard that they were on a few late 1970 and early 1972's. The 7041263 was used on low performance 400's and I think 455's. These carburetors venturi measures 1.093. I had one flowed and was told it flowed inbetween a 750 and a 800. The Pontiac community always refer to these as an 800. Is there an advantage to these over an 750? NHRA thinks so because they say they are only legal on the engines they came on. Danny

[Mark Yacavone]

It should be noted that most of the Chevy 350's and the 305's built after 75, didn't get the large primary (1.21 venturi) carbs . The SB 400's and the 454's did, though.

[Jim Wahl]

Danny,
Carter did make a Thermoquad they rated at 1000 cfm but it was an aftermarket replacement type carb. It was never an OEM deal. I think it was the Carter Competition Series 9000 and 9001 models. BTW none we ever flowed made anywhere near 1000 cfm. The 750 and 800 cfm ratings are much closer to being realistic but still over rated.
Jeff, I have never seen or heard of a "Red Bowl" Thermoquad. Sounds like an Urban Legend to me. The Motorhome Thermoquads were rated the same as the big block ones,(800cfm) they just had less smog crap involved. They were also available on certain big block Ford motors. Jim

[Neil Smedley]

I had a ` red bowl` 1000 cfm thermoquad years ago.....the only difference being the size of the primary boosters.......they took up a lot less area.......since most of the air enters the engine through the back barrels, I could not see an advantage