The Stovebolt Site Forums The Shop Area Engine Shop Carter YF 4376s

Maybe I can help a little bit...but there is a gotcha or two. While it wasn't the 4376S, I got a 4145S a few years ago and after some work on the throttle rod connector (because of differences in the design of the 230/250 and the 235 it had to be re-worked---the first gotcha---image of it below) I learned it will perform okay on the 235. Slightly on the rich side, though. I ended up thinking it would have run rich on the 230 and fine on the 250 and GM probably didn't care. The 261? Don't know because I don't have one of those. But the 4145 will work and because it is on the rich side I believe it might be close to okay on the 261. Another gotcha? You have to use a center screw air cleaner or spend time making an adapter. But it does have a manual choke and throttle can be rigged up (throttles by 1966-67 were almost all gone from GM vehicles).

Here is what I learned about the 4373 and 4376 and some other newer ones I've come across that were also used in 155/194/230/250 (like the 4480s)...these have the same throttle diameter and the same venturi size as the YF models made for the 235, but some have pressed in jets and the ones I've seen are largely worn out by varying degrees. A few horribly worn out. The metering rods chatter in them and wear grooves and ruts. You may recall a month or two ago I showed how I was making replacement jets (that could essentially be made in any needed size). I think...but have not had the time to experiment because of some personal stuff...that tinkering with metering rod sizes, metering rod timing and jet size could produce carburetors from these that would work on the 235 or 261. It is another project.

If people here are committed to having a manual choke and throttle, it is becoming hard to find Carter YF carburetors that will work. And staggeringly expensive.