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I hate to say this, but im on a highschoolers budget and when i purchased my 61 Chev w/ 235 it came with a Carter YF or YFA carb and thus have no funds for a brand spankin new Rochester 1bbl. I dissasembled it and cleaned it then went to geta rebuild kit, and the needle for it out of the YF rebuild kit was twice the size of the original, and the parts were wrong. what should i do? How do i accuratley identify it, because obvbiousley i mis-identified it. Im also thinking if i should buy a not terribly used Rochester 1bbl? Please any suggestions or info is greatly accepted!

This site may help you with id and proper kit.

www.thecarburetorshop.com

There should be a stamped number on the flange that will tell you your carter model number

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Mine is a 787s

Here is a 2100s
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Is the the needle your refering to?
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Original on left

Keep the Carter. I replaced my two Leakchesters with Carter YF's a few years ago and never looked back.

thats funny, I have never heard of anyone wanting to get a rochester instead of the carter...

Once in a great while we get a call from someone building a "museum" vehicle that will not be driven, or a numbers matching show vehicle that will be driven only on and off the trailer; and since the Rochester was original, that is what they want.

Jon.

My Hydra-Matic is not a museum vehicle and I run an original-spec Rochester BC on it. It works fine and does not leak. I also set up a pair of professionally rebuilt 1954 235 truck Rochester B carbs on a 1960 261 with dual intake/exhaust. They still behave nicely and they are not yet leaking (a friend now has that truck).

Off Topic
Yes, I know that many/most old Rochester carbs leak. And, I know that "feature" cannot reliably be remedied.
Carter's are probably better, but I have thinking of putting on the 261 either:
- dual GMC 228 Zeniths, if I they can be set up with the adjustable jet; or,
- a Rochester 2GC (for a 265 or 283 V-8) if it can be easily adapted at the base.
I'm no expert, and no technician, but I like to play.

Tim - the adjustable main jet on the Zenith 28/228 is a wonderful adjustment tool when using a single carburetor. However, trying to use the adjustable main metering jets in a multiple carburetor environment is an absolute exercise in futility UNLESS you have access to both a chassis dynomometer AND a really good exhaust gas analyser. A lot of experience doesn't hurt either. I have the necessary experience, but not the diagnostic tools. I would not do this on my own vehicle. But good luck if you do.

Jon.

Jon, the headers we used on the dyno when setting up round track engines had thermistors in every exhaust port connected to a pyrometer gauge. It was interesting to watch the difference in port temperatures under load created by slight differences in gasflow to individual cylinders. We used those numbers in addition to 4-gas analyzer readings when making jetting changes, and fine-tuning port modifications, etc. All that was done with a single big Holley 4-barrel on a single-plane manifold on a 355 cubic inch roller cam engine. We were above 600 HP at 7,500 RPM, and still building torque. We didn't max it out because we were already above the RPM the car owner planned to run and he didnt want to take a chance of hand grenading the engine. Multiple carbs really make big changes in exhaust port temperature. Sometimes it's necessary to change jet sizes from one carb barrel to another, primary and secondary, to equalize the power from different cylinders.
Jerry

Jerry - I completely agree; and have been suggesting this for 30 years, but with fixed jets, not adjustable on multiple carb setups that require synchronization.

When one is running a multiple carb setup that requires synchronization, the adjustable jet simply gets in the way because the tuner has no way of knowing the value provided by the jet.

As to the issue itself of different jetting for different holes, sometime check out a late 1960's dual quad hemi. The factory calibration is different for each of the 8 throttle bores.

Most tuners leave power on the table, whether it is a single carb or a multiple setup by failure to completely understand both the carb, and the flow characteristics of the intake manifold.

Jon.

Jon,

Thanks for your opinion (I was hoping you would respond with opinion and advice).

What carburetor would you recommend using as a single carburetor on an original manifold of a 261 bored to around 270 ci (over bored .060") ?

1. With original 7.5 approximate compression ratio

2. With an "848" head from a 1960 235 - approximately 8.25 compression ratio

It would be nice if the carburetor is one that could be easily tuned/adjusted/jetted on a 261.

Thanks,

My recommendation would be either a single Stromberg or Zenith WITH the adjustable main metering jet in a S.A.E. size 3. Which one? This is where the homework comes in. Since you now have a 270, and G.M.C. built a 270 with Zenith carb; compare your engine to the original G.M.C. 270. Take a look at compression, cam specifications, and desired RPM. Now take a look at the internal venturi used on the 270. If your engine is a bit stronger, add 1 or 2 mm to the venturi. If your engine is a bit weaker, then subtract a mm.

Probably, you will end up with either a Zenith 228 size 12 or a Stromberg BXV size 3 with an internal venturi from 30~34 mm. The homework will tell you.

Jon.

Thank you very much, Jon