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Best factory GM 2 barrel carb

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Best factory GM 2 barrel carb

Postby levisnteeshirt » Thu May 13, 2010 8:17 am

whats the best factory " stock and totally stock " GM 2 barrel carb ??

i was reading today the 1970 400 sbc is bigger than a 1973 ,,

what about the factory 396 2 barrel ?

an inquiring dirt tracker friend needs to know
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Re: Best factory GM 2 barrel carb

Postby F1Fever » Thu May 13, 2010 8:58 am

what intake do you have to run? a stock GM 2bbl?
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Re: Best factory GM 2 barrel carb

Postby brechlrl » Thu May 13, 2010 9:13 am

In 67 or 68 you could get a 2bbl on a 455 Olds
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Re: Best factory GM 2 barrel carb

Postby levisnteeshirt » Thu May 13, 2010 9:35 am

yeah they have to use an untouched intake and they do check them
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Re: Best factory GM 2 barrel carb

Postby jmarkaudio » Thu May 13, 2010 11:08 am

How about something off of a truck or bus?
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Re: Best factory GM 2 barrel carb

Postby ZIGGY » Thu May 13, 2010 12:12 pm

For 2 barrel circle track carb knowledge, call Dayton Umholtz, Kinetic Performance Carbs - 607-277-6462.
He can help improve the "stock" part too if your friend so desires.
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Re: Best factory GM 2 barrel carb

Postby PackardV8 » Thu May 13, 2010 1:46 pm

Yet again, it costs more for the best built race 2-bbl carb than a off the shelf 390 CFB 4-bbl.

Every time I get involved in one of these "stock intake, stock 2-bbls" I always come away wishing they had chosen one spec aftermarket intake and carb. Easier and less expensive to find, easier to build, easier to tune, easier for tech to check, since there is only one possibility. Does away with arguing that this is one of them rare Canadian school bus non-EGR 600 CFM 2-bbl carbs and intakes and is really completely stock even though it looks like half of a Dominator, can't happen.

thnx, jack vines
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Re: Best factory GM 2 barrel carb

Postby levisnteeshirt » Thu May 13, 2010 2:19 pm

i think the 4412 500 cfm holley should be the standard " stock class " dirt racing carb

i had a friend that would buy every 5-600 dollar " stock " carb he could get his hands on 20 years ago because he was afraid his competition would

but this track requires a " stock " carb ,,,

i wonder if a person could graft a rottenchester front bowl onto a 6425 650 2 barrel ,,LOL
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Re: Best factory GM 2 barrel carb

Postby Cogburn » Fri May 14, 2010 12:09 am

Any of the 1 3/8" venturi carbs can be made to run. The biggest stock venturi is 1 3/8". After that it is the fuel curve.

Good luck.
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Re: Best factory GM 2 barrel carb

Postby Troy Patterson » Fri May 14, 2010 5:39 pm

Rochester 2GC went as large as 450 - 500 cfm. Pretty good carb and yes, it's all in the fuel curve. More to be gained or lost in fuel curve than trying to cheat the venturi.

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Re: Best factory GM 2 barrel carb

Postby ProPower engines » Sat May 15, 2010 12:59 pm

What about the merc marine carbs. I have seen a couple local stock car guys use them and when i was tech guy they appeared to have a larger venturi then the rare school bus carbs that guys had. (they did not look like half a dominator)lol but still a bit larger and the guys that used them said they were a bit of work to get tuned............
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Re: Best factory GM 2 barrel carb

Postby levisnteeshirt » Mon May 17, 2010 6:06 pm

hmm ,, i saw some of those carbs ,, wondered if they were bigger than the auto carbs ,,
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Re: Best factory GM 2 barrel carb

Postby Fahlin Racing » Fri Jun 04, 2010 2:26 pm

I have some experience here. The local short track oval near where I grew up restricted us to only iron 2V intakes and the 2GC. They wouldn't let me run the factory aluminum 2V intake and any 2GC Rochester produced for a car, not a truck for no explained reason. I had the same discussion about why the 4412 should be used with him and he just didn't understand I guess. If you have specifications that need to be met as far as Venturi/barrel diameter I have been told the truck 2GC units have a slightly larger diameter than the car units. I have not come across a truck carburetor in particular, so I can not give you a 100% accurate answer as to the possible differences between the two. Sorry about that.

Ask if they require a stock SPECIFIC intake relative to the engine displacement and model year or not, because you might be able to run any 2V intake manifold that is iron plus a 500cfm 2GC carb if you can locate one. I was told by a guy who apparently used to race bombers said the 1960s 2GC units had removable jets I believe?? I am too young to know this off the top of my head, maybe one of the older gearheads among speedtalk could chime in to verify that or not.
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Re: Best factory GM 2 barrel carb

Postby agawam » Fri Jun 04, 2010 4:00 pm

the large 2G carb came in four sizes352 381 423 and 435 cfm, venturi sizes were 1 3/16, 1 1/4, 1 5/16, 1 3/8 respectively, the best intakes were 70-71 400 2bbl made in canada and some not marked canada but with casting numbers "6313" "3487" "3752" "8467" , and then some cheater intakes made by brezezky and others, sean murphy builds carbs as well as a few others in 500cfm,the @g carb is a great carb and the stuff is out there ,jets acc pumps power valves in stock or holley conversion, I have one of those marine carbs its huge but has onle one mixture screw also have a truck carb from a C60, seems to have a thicker base than the others, olds pontiac and buick put them on their 400s and 455 engines, in 68-9 chevy used them on the 396 with trailer package and 70-2 the 400 sbc, I just bought a carb off ebay still in factory plastic for a 400 455 pontiac for less than 60 bucks, a few years ago I put a carb and intake on a chevy 305,replaced the sad duo-jet, the car would roast the tires after that, the 2G carb is my favorite, everytime I'm in the boneyard I check for them and grab what I can, try one with a 1 or 2 inch spacer, low end torque unreal, I first noticed this carb when I bought a 69 belaire 4 door with an open chamber 396 with a 2bbl and turbo 400,9:1cr for 50 bucks, this car would literally rip the rubber from the wheels, so I carried two spares and a jack all the time, thinking it was an improvement I put a 4bbl and intake on and it was a dog so I returned to the deuce
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Re: Best factory GM 2 barrel carb

Postby Fahlin Racing » Sat Jun 05, 2010 7:20 am

Agawam, you have posted some great information and helped more than one person as well!

Thank you :D
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