Inliners International Forums General Discussion Engines Rochester Model B 1 barrel

I am looking for a pair or at least one Rochester Model B 1 barrel carb with 1 inch venture.
For those of you that don't know what I am talking about it's the center opening above the throttle body not the air cleaner mounting horn. Most of them are 1 1/4 but there are at least 7 different sizes 1 inch is the smallest and hard to measure.
Can someone help?

The smallest one I show is a 1-1/16" venturi.
I guesstimate its flow at about 96cfm at 1.5" Hg (the 4bbl rating), the perfect size to feed about 60hp.
Yup its tiny.

I did a carb shootout with a bunch of these carbs:
1-1/16" venturi ~96cfm
1-11/32" venturi ~140cfm (the most common car 194 and 230 carb)
1-9/16" venturi ~185cfm (mainly 292 trucks but also the 250cid and the 230HiPerf)
The 250cid and 292cid launched just as well with the big jug as it did with the medium size carb if the carbs were set up right.

That little 1-1/16 job (I only have one) ran like a sick dog, WAY too lean until I punched out the power valve hole. Even when I got the mix right, it was just way too small, I had to guesstimate the airflow at 96cfm to match what the GTECH was telling me. Even two of them is only the same size as a single Big Jug "B" carb, which is still too small for almost any six.

If you plan 2 carbs you might try a pair of the more common 1-11/32" venturi, they are dirt cheap at swap meets.

What is your engine build?

My engine is a stock 235 duel Fenton intake and exhaust. I have the infamous hesitation. I want to run duel Rochester's I am hard headed. LOL I was told there isn't enough vacuum with larger ventures to give me the off idle circuit fuel draw.

My engine is a stock 235 duel Fenton intake and exhaust. I have the infamous hesitation. I want to run duel Rochester's I am hard headed. LOL I was told there isn't enough vacuum with larger ventures to give me the off idle circuit fuel draw.

So are you running dual carbs right now & its hesitating?

My method is to use a single carb intake, wring the carbs out 1 at a time and find my favorites (as I said the mid-size carbs are cheep). Some of them do hesitate, but some I can punch right off the line to the floor. Get a pair like that and they might work as duals.

What about initial timing, sometimes that helps or a quicker timing curve? A retarded cam will also make it more prone to hesitate, have you degreed the cam in so you know where it is? Of course gears don't stretch like a chain but I always check anyway

I show the little 1-1/16" "B" used on the 60-62 truck, 235 economy option.

Some of the old 216 Carter BB carbs are also this small but of course theyre not Rochesters.

I found out luckily that my fuel line was clogged at the tank and was starving my carb's it just quit in my drive way and wouldn't run so I blew out my line from the fuel pump to the tank and it runs a lot better. Who would have guessed that one all new lines and such but old tank oh well. Problem solved I guess it was getting just enough fuel to run weird stuff happens to me but hey I was at home. I will drain the tank later and clean it out good.

There used to be a Tech Tips Section on this site. One of the articles was titled "Improving Drivability With Multiple Rochesters". The article explained with pictures how to modify the idle circuit, high speed circuit and high speed power valve circuit to correct for the low vacuum to each carb. It might help you if you can retrieve it from the earlier Inliners web site.

I read about that article and Tom Langdon said all I would do is ruin the carbs when I ask him about doing it.
Have you heard if anyone else has had success doing that?
I could do it easy enough I have a ton of carbs and the means to do it.
I might try it any way to see for myself.
Thanks for the info.

I did the power valve opening trick as noted in the article.
That did the trick on the little 1-1/16 carb.
But mainly, I like it cuz you are at most ruining the "tower" that holds the spring, jet, etc. You can swap in another one if you ruin it.

I have not tried drilling the idle passage in the air horn though it seems a reasonable fix to the hesitation. This is sometimes done when running a big cam when you need a lot more idle and transition volume of fuel/air. Bad part of this trick is, once you drill it you kinda ruin the lid if its too far, so then you have to swap on another similar carb lid.

Sounds like you fixed your problem though?
Yup those old tanks and the sender/filter/sock can get full of crud and goo.

I am still looking for another 1 1/16 carb I haven't heard from anyone whether they will part with one or not. Might you have one you would part with in stock condition? Or know someone?

fyerman,
Oh OK, I didn't know you still needed one.
Well since nobody else has bit:
* I only have one small BC carb, was kinda hoarding it but realistically not likely I will ever use it.
* If you need it see how $30 sounds plus flat rate ship to you in a medium box, we can PM or Email the rest
* Here is its history:

Got the carb in a box of stuff in a 64 Nova 283, obviously the wrong vehicle. Sat for years til I did the Carb/Intake Shootout a couple years ago, I compared all the 1bbl vs 4bbl carbs I had.

I cleaned the Little BC as best I could, can Email photos, and put a kit in it and a different iron base as the original was frozen. It came with
Jet 42 PVCR .027

I then ran some 1/8 mile shootouts as follows.
This was in a ~2900 lb Nova, stock 250 Powerglide 3.08 (no traction issues for sure)
Jet.PVCR 1/8-mph
Jet 42 PVCR.027
12.311-55.69 as rebuilt.

Jet 52 PVCR.027
12.162-55.12 a lot better on the launch

Jet 58 PVCR.027
12.765-52.31 too rich, ran and drove like a soggy wet dog

Jet 42 PVCR.036 drilled out
12.064-56.42 best of the bunch for this carb

Jet 42 PVCR.036, 1 of 2 top idle air bleeds epoxied shut
12.131-56.04 thought this might help but it really didn't

For comparison here is a typical "mid-size" BV carb, the 1-11/32 venturi that came in most 194 & 230 cars:
11.496-60.69
That's over 3 carlengths faster just in the 1/8 mile and over 4mph. This is why I was not impressed with the Little BC. One of them is just too small I guess even on a stock 250.

That said, it did idle and drive ok, it was just slow, kinda like blasting down the 1/8 mile with your foot only 1/2 way down.

See what you think or give me a PM