The Stovebolt Site Forums The Shop Area Engine Shop what's the cfm requirement

from a stock roch, or whatever other 1bbls that were/can be used, on a 235? even rebuilt, those little devils are salty

Pretty much can use a 1bbl from any engine that is near a 235 ci displacement. The Rochester, known as a "Rottenchester", has a lot of picadillos associated with it. Leaking gas, worn throttle shaft bushings, and lazy accelerator pumps are common problems but these were never enough to keep me from using them. Many opt for the Carter or Holley replacement 1 bbls. I have used ones from a 230ci Chrysler flathead 6 but my favorite is the low profile 200-250 Ford six, including the one with the transparent float bowl. I discard all the rods and the bellcrank on the block and use a pedal/cable set up from a later Chevy pickup. Alignment is not a factor, the cable can be routed so it pulls in the right direction and at the correct angle, and either a manual or automatic choke can be fabbed up but with these carbs the pump squirt is so positive that in Texas a choke is usually not necessary. Not true for colder climes. Disregard all this if you are an original purist. A down and dirty way to ballpark CFM is take 1/2 your engine size (117.5)x maximum rpm (3000 normally for a 235) and then divide that by 1728(ci in a cf). In this case 117.5 x 3000 divided by 1728 ='s 204 CFM carb size.

and from my manual, carters and gm model Bs were used. is a gm actually a roch? and going by the formula, how does it account for duals and trips?

Rochester was or still is a part of GM. Carter made carburetors for GM as well, so both are correct.

As for CFM and dual or triple set ups, the engine never needs as mch air as a carb can flow, plus thats why most multi set ups are hard to make run.

Have you ever stood behind a small block with dual four barrles and a tunnel ram intake when it was running?

Joe

stood behind? no, but does it work as a replacement for foreplay? i'd seek it out if so