The Stovebolt Site Forums The Shop Area Engine Shop 235 Fenton 2 1 barrel Rochester b carb choke ?

I have a question about running the 2 Rochester 1 barrel carbs with a choke on just the rear one. I have one really good carb and one the choke butterflies and top springs are crap so I was thinking about taking all of the choke system out completely butterfly, rod, all and just using the rear one as a choke, I know not the best way but seen several done this way and it doesn't get extremely cold here. Have any of you done this and what did you do about the holes once the rod is removed?

Brads1951,

One choke connected (rear one) worked fine for me. You might want to consider somehow "tying"/holding the unused choke valve/flapper open but leaving the parts in place.

I dimly recall reading here that removing the valve/flapper parts somehow affects air flow.

Let's see if someone who knows carburetors clarifies/corrects this.

What size engines did the two Rochesters come from?

They came from 55-57 235. I have two 216 rochesters but their bolt pattern is the smaller ones that don't fit the Fenton intake. I looked for adapter but no luck and I don't want to have the intake welded up and redrilled.

Tim is correct on the airflow. Having the choke butterfly functioning actually IMPROVES airflow at lower RPM (probably below 3500 or so).

With 2 carbs, both should be IDENTICAL for best results (unless you are looking for the absolute maximum WOT horsepower and have access to a dynamometer and some sophisticated individual cylinder temperature measuring devices).

Not saying it won't work the other way, because it will; just not as well.

Jon.

Okay, I've read on other websites that some Rochester 1 barrel 216 carbs (everything but the bottom main throttle butterfly) can be exchanged with the 235 bottom throttle butterfly to work on Fenton intakes. Is this what most of you are doing to be able to use 216 carbs on the wider intake

I passed on the Fenton and bought an Offenhauser because they came in either the big or small bolt pattern.
That doesn't help unless you want to return the Fenton.

Rochester spent the money for additional research, development, and tooling for multiple sizes because they were making too much money!

Jon.

One more question should I run the carb isolators that were originally on the stock intake on the Fenton? Just needing to know ahead of time so I can order them if so since mine are all junk. I did already rebuild one carb 216 with the 235 bottom and it all bolted together perfect

At this point, with mixed bases and unknown carb models, the spacers won't really matter. The dual intakes do not heat up as well as the stock intake since the carbs are spaced out away from the center heat. Spacers help cool the carb, you should not need them and they can always be added later.