Rochester 2G (2 Barrel Carb)

Discussion in 'Other' started by Gary Farmer, Jul 1, 2013.

  1. Gary Farmer

    Gary Farmer "The Paradigm Shifter"

    Did some research on this carb and found out some very interesting data. Seems it's one of, if not the most durable and dependable carbs ever made, and they came in about 5 different flavors!

    From what I understand, there were two base sizes, the small and the large. The small came in one CFM size (278) while the large came in four sizes (352, 381, 423, and 435 CFM). Aftermarket vendors have capitalized on this durable and dependable carb by gutting it out and turning it into a 500 CFM carb for dirt track racing. Imagine what this carb could do on a small block!

    The small base was used up to 1971 on everything, while the large was introduced in 1971. By 1973, all Buick engines used the large base.
    This data might be a bit off, but it's what I found. Tried looking for more specific data on these carbs and only got lost in the jungle.

    Do a google search and type in "Rochester 2G" in the search box. I've found everything from forum archive discussions to dirt track racing to vendors who sell rebuilt carbs to personal testimonies to old 1950s-60s document data service manuals.

    DEADMANSCURVE my first word : truck

    yep - always thought a 500cfm on like a 300 instead of spending huge bucks on a 4bbl intake might work well . a little plenum work n port matching , maybe some cold air . plus look kinda stock .
    found about the same kinda info on internet , stock specs etc plus a couple dirt track sites that had some mod info .
    mopar performance used to list a 2bbl small block intake for certain classes . i think it may have been cast but for sure not stock height or runner design .
    i know summit list's the Jet mod'd 500 2G carbs .
    my first car was a 64 special wagon , 300 , three on the tree car ( switched to a 3 speed comp plus ) . put a holley 500 2bbl on it - ran good .
  3. shiftbyear

    shiftbyear Well-Known Member


    DEADMANSCURVE my first word : truck

    interesting . read over the e-bay info and i see he makes them to 700cfm also . when i went to "other items" it looked like he also sold parts - hi flow needle n seats , etc .
  5. 74regalnz

    74regalnz Well-Known Member

    Hi guys, was looking at my options for a carb and found these. Because it will cost me a kidney in shipping to get a stock 4 bbl inlet to the bottom of the planet. I wondered had any one tried this type of carb on a stock 350 ? I see he also makes 600 & 700 cfm carbs. My car seams to starve above 70 mph if i floor it but idle is OK and if i hit the gas at start it spins the 295s on the back. yes i have new inline filters and new air cleaner but the carb itself looks to need at least a clean and kit, local suppliers just don't support Buick down here so all my parts need to be shipped. Any other tips will be great fully received
  6. Gary Farmer

    Gary Farmer "The Paradigm Shifter"

    I'll let a little secret out that I was toying with the idea of using a 2G on a 350. I mulled over the pros and cons in my head and I'm still not 100% decided.

    The first Buick I ever owned was a '68 Skylark with a 350 2G carb, and it ran so good people swore it was a 4 barrel carb. I tweaked and tuned the engine and it would burn rubber all day long.

    Its biggest weakness was when the engine started to rev, the power would trail off because the engine was starving. This was the small 2G I believe, so a bigger one would do even better. With a mild cam like a Crower level 2 and a big 2G, I imagine the low-mid range torque would be pretty incredible.

    Biggest problem I see with it is gas mileage. As long as you babied it and didn't put the pedal down too hard it would do ok. Not as good as a Q-Jet, but not shabby. This would require a highway gear or just slow driving.

    Partial throttle it does great and there's no transition between 2 and 4 barrels like on a 4 barrel carb, so you have all your power instantly on tap. Low end and mid range torque is amazing.

    Get one too big like a 600 or 700 and I imagine the gas mileage would suck. My biggest drawback to using one.

    Dare to be different! :grin:

    ---------- Post added at 10:47 PM ---------- Previous post was at 10:14 PM ----------

    Let you guys in on another 'secret'...

    You can modify a 2 hole spacer so that each hole is wider at the bottom than it is on the top, which creates extra draw from the plenum and makes the carb act bigger than it actually is. This would also help a 2G on a larger CID engine such as the Buick 350. You would have to match the intake holes to the bottom of the spacer so they are either even or the intake holes a little larger, and smooth the spacer out so it flows out evenly into the intake.

    Fuel/air mixture ratio is great on these 2 barrel intakes, because the carb sits in the middle of all the action and everything is evenly distributed.

    There's more you can do to the intake too, but I'll keep that to myself for now. :Brow:

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