The Stovebolt Site Forums The Shop Area Engine Shop Rochester B vs Carter 4375S

OK - Shifted gears & now back on the 67.....The unanimous preference was the Carter over the Rochester....Physically all looks good with the exception of the gas pedal linkage....No way the Carter will hook up to the linkage????

Would it connect correctly if the Carter was mounted the other way?

After the fruitless attempts to get the Rochester to work properly, it was suggested that the Carter was a better carb....then someone was kind enough to send me a Carter spec list which identified the exact model carb for a 1967, 250 cu in, manual choke...which is 4375S.....I located one, and was under the impression that it would be the correct fit & replacement for the Rochester.....I'm not really inclined to modify the linkage or start making any modifications to the carb....It either fits or not....On a previous post I considered a Chinese aftermarket just to see if I could get this truck to run 'off choke' I didn't get any encouragement, that's when the topic shifted to the Carter...... So now I'm back to square 1......I'm just not getting all of these posts that are carburetor related problems....The truck starts, on choke, warms up and won't idle when the choke is pushed in, in attempt to keep it running I have to rapidly pump the gas pedal however it will spit & sputter.... Its not a vacuum issue as I checked it....all the reference is on my other post.....What could be so wrong???

I have 1954 3100 with the original engine and 2 Rochester Bs. Yes, L know that some on here don't like the Rochester Bs and I was almost convinced to spend $1000 to replace them but I just got back from a 1250 mile trip with them and they ran flawlessly. Literally ran all day at 60-65 mph.

OK...Lets start with the truck itself...It is a 1967 K20...built in Oshawa....When I google production numbers, I find a hyphen for units made, (I have another post on this)...leading me to believe this is a pretty rare truck. There is also evidence the originality of this truck suggests, that it was in the possession of the original owner up until several years ago.....then it changed hands twice before I got it.....This truck is a 100% survivor with 100% original paint, even down to the original Harrison radiator. Unfortunately I was unable to obtain any history on the truck. The guy I got the truck from was vague in providing any details of who he got it from, other than it was obtained from an estate..The guy I got the truck from said he could never get it to run right and said the carburetor needed to be rebuilt. I had no intention on another truck, but the attraction was the originality and the fact it was NEVER MONKEYED WITH....I had my fill of undoing crap with vehicles that fell into the wrong hands..I was in my late teens when these trucks were new. I worked for a GM dealer that had a 68 shop truck, with a 250 3 speed and that truck never gave an ounce of trouble....I can almost bet my life it had a Rochester....I can hardly recall any Rochester issues.... I have a 72 GTO which I bought brand new with the original quadrajet that often lays for a year or two at a time, and I never had the carb off the engine. I get in, set the choke with one push to the pedal, it cranks, fires up on high idle, warms up, & I kick it down.....PERFECT .....I also know that time & age plays a factor, along with the differences between NEW & REBUILT.... and I know I'm on a rant here but, I got off track with 'Options' where my inclination is always originality ....This vintage era GM was the high water mark...So my point.....There really is no reason to to find alternatives....I know there's a tiny fragment of issue with the Rochester....My plate is full with other real life responsibilities.....For desert, I will find the time & opportunity to take apart & dissect this Rochester with no interruptions.....and am confident that it will once again it will perform as it once did...I Thank you all....

According to the manufacturer's information; both Rochester and Carter were used on the 250 in 1967 as original equipment.

The 4375s was used only on standard tranmission federal trucks.

Federal trucks with automatic transmission used 4376s.

There were also two different Carters for use on California only trucks.

Did Chevrolet use different linkage for Carter versus Rochester? I do not have this information.

Since the 4375s was used as original equipment on the 1967 250 with standard transmission on a federal truck, one would think that it would bolt directly on with no issues (unless Chevrolet did use different linkage).

One comment about issues with Carter and/or Rochester: Carter made some dogs, specifically the models BBR, AS, and RBS. Not all Carters are wonderful designs. Rochester made some really great carburetors, specifically Q-Jets (after 1967), and the 2G (2-barrel) and 4G (4-barrel) carbs. But as in any manufactured product, there will be some good and some bad. The are some individuals that have had no issues with the Rochester B's, and others that have had issues with the Q-Jets. But if one looks at the overall averages (and I have been doing carburetors for 60 years, so some experience) one comes to a conclusion as to the probability of success with a given model.

Jon.

As my pics show the throttle linkage is on the opposite side pf the carburetor...lending that although the carbs may interchange, the linkages do not..... Also to be noted that I blame no one for suggestions or involvement in my posts...we all have a shared common interest and despite the successes and failures of suggestions, I feel intentions are sincere & genuine....My feelings on modifications hinge on the negative side.....A lot of research and testing goes into development, and who am I to change that.....My 70 - 292 has a Rochester and runs perfectly, so its a flaw or imported issue that I'm experiencing with my Rochester B on my 67, not a 'No good' Rochester..... I hope to figure it out........