![]() On the hood was a pair of functional air scooped which provided cold air for the 400 cubic-inch engine which breathed through dual exhaust pipes. On the front fenders were twin fiberglass, rear-facing scoops which acted as vents for the engine heat. The Trans Ams were painted in cameo white paint, had medium blue stripes, a full-width rear airfoil, and dark blue deluxe upholstery. Ben Harrison and Jim Wangers worked on product planning and marketing. Under the direction of Chief Engineer Bill Collins, Herb Adams worked on the chassis development. In March of 1969, Pontiac announced the arrival of the Trans Am option for its Firebird, based on the prior Pontiac Firebird Sport Turismo and Tunnel-Port racing projects. The late 1960s was an exciting time for the American automobile, as horsepower continued to rise as drivers went down the road a quarter-mile at a time. 'Trans Am' was also a known name in fact, Pontiac had to pay a $5 royalty per car to the SCCA due to the vehicle being named after this popular SCCA Trans-Am racing series. The name 'Firebird' was not new it had been used by GM on 1950s and early 1960s concept cars. It shared its platform with its GM Chevrolet sibling, the Camaro. We never had customers complain of idle issues with the single booster Q-Jets that we built.The Pontiac Firebird was in production from 1967 through 2002. Rochester got the idea for the 1971 Q-Jet with the missing booster from the thermoquad, and those who had run the 1000 thermoquad may have just assumed the Rochester would also have idle issues. The 1000 CFM had the outer booster ring removed, AND THE 1000 CFM DID HAVE IDLE ISSUES. The early release thermoquads were designed for race only, and were released in 8 CFM ratings. In 1969, Carter released a larger version of the Q-Jet called the Thermoquad. Wonder what the bean-counters thought of this? The Carter and Rochester engineers were actually SHARING data (what a revolutionary concept!!!). Remember that in the late 1960's and early 1970's, Carter was building lots of Q-Jets for GM. The "myth" may be based on facts with an incorrect interpretation. I think it's an incorrect myth that they don't work well. I run a 7041267 (single booster ring) carb on my '71 T/A with no issues whatsoever - runs great from idle to wide open throttle. Not sure exactly which engines got the slashed vent. I can't see much difference in the '68-'70 models which had the slashed vent. As most know, the 704 numbers began with the '70 models. The 1st pic is of a #7040273 small vent model. So, for some of you Q-jet experts, were there some of the late '70 models which had the big vents ? ![]() The small vent model will look more correct for a '70 model car.Īlthough the above article, and Cliffs book says the big vents started with the '71 models, this '70 Model, on Ebay, has a big vent. But, if you don't mind cutting a hole in your air cleaner base, then the big vent models will work. This opens up the choice between the '68-'70 type, small vent models, and the '71-'74 big vents. ".Anyone have a nice rebuilt or rebuildable 750 cfm (4spd) from a early second gen?" should be able to perform just as well as any 800cfm casting - assuming you're not running an engine that has enough displacement to need that extra cfm. IMHO, the 7040263 which is a correct casting for: The next options for this cfm core are 1973/1974 455SD carbs - but they have a different choke setup which will not work with a 1970 intake manifold, and will require a different corresponding air cleaner base. That is to say that if your Formula originally came equipped with a 7040564, 7040563, 7040570, 7040573 carburetor, then your air cleaner base has provisions for the 71-74 style Rochester 4bbl fuel bowl vent. The only early (70-73) 2nd gen 800cfm castings are:ġ) 1971 455HO (7041270, 7041273, 7041267, 7041268)Īll of these castings can be used with a '70 intake manifold, but will require a specific to 1970-California air cleaner base FYI (and I'm going off memory, so hopefully I have all the numbers typed correct)
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