i would say it depends on if your trying to make your car stock ? if not i would go with the 4 barrel smaller primary = better gas mileage like u said . And better performance . As long as u keep your foot out of it . but it is realy up too u as u are the owner of the car an no one else is .
5150 4cars = carzy4cars my car= 68 firebird 350 jim butlers ported heads an intake , 4 speed , 3:73s
I found it interesting that when I modified the factory Ford 302 2Bbl in my last truck with an Edelbrock cam/4Bbl carb/manifold set, it did not make the gas mileage any worse.
2012 Mustang Boss 302 #1918, Competition Orange. FGF replacement 2006 Mustang V6 Pony, Vista Blue. Factory ordered. 2019 BMW X3 (Titled to the wife, but I'm always driving it for her. So I'm claiming it) Old projects, gone but not forgotten: 1967 FB 400, original CA car. After 22 years of work, trashed by the guy who was supposed to paint it. I had to sell it. 1980 Turbo Trans Am 1970 Mustang fastback, 351C 4Bbl, auto 1988 Mustang GT, 5 speed 1983 F-150 4x4, built 302 1994 Chevy K2500 HD 4x4, 454 TBI
They come up on the parts for sale listing here all the time, and on eBay. Things to watch out for...make sure it's a '67 to '72 Pontiac intake, and yes it will be set up for spreadbore, ready to bolt on a Quadrajet.
Vikki 1969 Goldenrod Yellow / black 400 convertible numbers matching
A larger Rochester 2-barrel (re-calibrated specifically to your engine) would give somewhat better (measureable) performance, with no loss of fuel economy under normal driving conditions.
Most, when they say "500 CFM 2-bbl" are referring to the Holley 4412. This carb would give somewhat better (measurable) performance, with a large loss in fuel economy. In other words, roughly the same performance gain as a larger Pontiac Rochester 2-bbl, without the fuel economy. This unit would not be legal on your vehicle if licensed in the USA.
A Pontiac Carter AFB from the mid 1960's on a 1965 or 1966 intake would give you better performance with about the same or somewhat better fuel economy, but is not legal for your vehicle if it is licensed in the USA.
A properly calibrated Rochester Q-Jet on a 1968~1972 Pontiac manifold (I agree with Vikki that a 1967 would also fit, but it has issues due to the heat passage and is better left to the restorers), would provide much better performance and better fuel economy under normal driving conditions.
A properly calibrated Carter TQ on a 1968-1972 Pontiac manifold (see above) would give you the best performance and better fuel economy under normal driving conditions. I am using this carburetor (part number 9800) with an aluminum 455 H.O. intake on my own high performance Pontiac 350.
Jon.
Good carburetion is fuelish hot air Owner, The Carburetor Shop LLC
Vikki - one should start with one of the aftermarket units. Numbers which are applicable to Pontiac are:
9800s (800 CFM) electric choke (smog legal through 1974) 9810s (modification of 9800s to include EGR port)(smog legal through 1974) 4846s, 4846sa (850 CFM manual choke race only) 4847s, 4847sa (1000 CFM manual choke race only)
The 4847s was tested by Pontiac on the RA V engines. The RA V which set the various performance records was using the 4847s.
The 9800s and 9810s will bolt to the Q-Jet intake, linkage will fit from most Pontiac installations. Fuel inlet is in rear (fabricate new fuel line). Original air cleaner may or may not fit, as the TQ has 2 huge bowls, one on either side. Some of the "pancake" wrap-around original air cleaners will hit the bowl unless a 3/8 spacer is placed between carb and air cleaner.
Other TQ's (as far as Pontiac engines) are useful only for spare parts (floats, linkage, etc.).
While the 4846 and 4847 are listed by Carter as being race only, either can be used on a "pro-street" engine with standard transmission. I would never recommend using the 4847 with a dogmatic tranny.
More information about these in Jim Hand's book.
Jon.
Good carburetion is fuelish hot air Owner, The Carburetor Shop LLC
I went from an old 2b to an edelbrock intake and a 600 holley with vacumm secondaries and a electric choke that and an HEI were the best things i ever did for my engine.
I modified part of my old linkage for the new holley and it really wasnt a big deal (just a little dremel work) you could go with an edelbrock carb (carter oar AFB are the same) just remember that the way the fuel line runs you cant really use a recessed base air cleaner
'67 Convertible Bird Blocks a '70 400 w/ 3sp auto on the column Deluxe Int
I intake weighs 42 LBs. My zip code is 53177. If you go to www.ups.com enter the weight add about 5 lbs for packaging enter you zip code my zip code and it will give you the cost. Let me know if you want it.
