62 C10 with 235 currently has a Rochester. The throttle plate shaft has a bit of wear and it seeps gas a lil bit. Prime the carb manually and gas will run out around that shaft . I dont want to rebuild a carb that is still gonna leak like this .
Ive done a lil reading and the Carter YF seems to pop up as a good swap. I found one I can rebuild, but want to hear some input from here.
YF2100s in the pic.
Last edited by fattboyzz; 05/22/20237:46 PM. Reason: Add
1962 C10 with a 235 6cyl -- all of the drive train seems to be original. Some of this story is in the Side Lot Some people like a new truck. I liked the old ones.
The carb that fits this truck and has a reputation for good mileage.
I dont want to spend wads of money ,but Im not looking for cheap either.
What would you recommend ?
1962 C10 with a 235 6cyl -- all of the drive train seems to be original. Some of this story is in the Side Lot Some people like a new truck. I liked the old ones.
For many, the correct "YF" is the choice to go with to replace Rochester B's. You do need to make sure the one you find is compatible with the needs of your '62 235 though.
There are a number of different "YF" carbs out there. Your picture is too fuzzy to see which model number that one is.
There is a stamped "model number" on the side of the main body casting which can be decoded to figure out what it's original application was before going further in this process. You also need to pay attention to the base casting number to make sure it's a correct match to the body as someone else's previous work/rebuild may have resulted in mismatched parts.
A big helpful info source on Carter Chevrolet YF 235 aftermarket carbs is provided by our own member expert "carbking". This link is just one of many to his "Shop" and I am sure he will probably chime in here with helpful info as he can.
Pic below is a snapshot of where to look for the "model" number on the "YF" you have.
Hope the one you found will work for your 235.
Dan
~ Dan 1951 Chevy 3 window 3100 Follow this story in the DITY Gallery "My Grandpa Carl's Truck and How it Became Mine" 1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
The fuel leaking from the throttle shaft is not due to the throttle shaft being worn. It is likely caused by either a fuel pump which has too much fuel pressure for the float, causing fuel to be pushed through the needle and seat, or due to the float being set to high, or a leaky needle/seat. A brand new carburetor with a "tight" throttle shaft will leak there if excess fuel enters the bowl.
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
Carter, Rochester, Stromberg, and Zenith all made carburetors for the Chevrolet 235.
The Rochester would have the lowest initial cost for a core, and maybe the highest cost to have that core professionally restored.
The Carter would be the next lowest cost for a core, and probably the lowest cost for a professional to restore the core.
The Stromberg and Zenith would have a much higher initial cost, and a higher restoration cost than the Carter, but much lower than the Rochester.
Fuel economy:
For a professionally restored carburetor, the Stromberg and Zenith might be 10 percent better than the Carter, which might be 10 percent better than the Rochester.
Reliability:
Again, for professionally restored carburetors, the Rochester MIGHT go 5 years without another full restoration, the Carter would probably go 5 years without a clean-out kit, and 20 years without another restoration.
The Stromberg and Zenith could be expected to go without service for maybe 100k miles or more, assuming fresh fuel was delivered to the carburetor.
Summary:
Lots of folks like the Carter, as a REBUILT, not RESTORED carb is relatively inexpensive with good fuel economy and reliability.
Leaking at the throttle shaft:
Re-read Carl's response above. Fuel leaks around the throttle shaft because of too much fuel in the bowl, once the engine is no longer running. Fuel will not leak at this point when the engine is running, as there is engine vacuum which would prevent leakage. The three most common reasons for leakage around the throttle shaft: (1) FLAPS kit with fuel valve orifice too large, (2) electric fuel pump, (3) modern fuel (it hasn't been gasoline for decades). The professional would NOT use the FLAPS kit, so (1) would not apply on a professionally restored unit, but if (2) or (3) are present, then the restored unit would leak.
Jon
Good carburetion is fuelish hot air The most expensive carburetor is the wrong one you attempt to modify. If you truly believe "one size fits all," try walking a mile in your spouse's shoes! The Carburetor Shop
For many, the correct "YF" is the choice to go with to replace Rochester B's. You do need to make sure the one you find is compatible with the needs of your '62 235 though.
There are a number of different "YF" carbs out there. Your picture is too fuzzy to see which model number that one is.
There is a stamped "model number" on the side of the main body casting which can be decoded to figure out what it's original application was before going further in this process. You also need to pay attention to the base casting number to make sure it's a correct match to the body as someone else's previous work/rebuild may have resulted in mismatched parts.
A big helpful info source on Carter Chevrolet YF 235 aftermarket carbs is provided by our own member expert "carbking". This link is just one of many to his "Shop" and I am sure he will probably chime in here with helpful info as he can.
Pic below is a snapshot of where to look for the "model" number on the "YF" you have.
Hope the one you found will work for your 235.
Dan
Its the YF2100s
1962 C10 with a 235 6cyl -- all of the drive train seems to be original. Some of this story is in the Side Lot Some people like a new truck. I liked the old ones.
The YF2100s is popular around here because it has a manual choke. That carburetor was designed in 1953 (or 1952 for the 1953 235). The 235 changed notably in 1959. If economy is what you want, the engine you have is a very good candidate, but just changing the carburetor isn't the whole answer. You can read about what GM did on their Heritage Pages. Essentially they went with hydraulic lifters and a camshaft that produced greater torque at a lower rpm. Doing this achieved an impressively long flat net torque line. Take a look at page 59 of this report:
The net torque reaches almost maximum at 1600 rpm and stays flat almost until the net torque line and net horsepower lines intersect (around 2600 rpm). At 2000 rpm your 235 is producing as much torque as it will produce. It is not common to find a torque line like that...almost 1000 rpm at more/less max net torque is neat. From the standpoint of economy, this has a message. It means you can lower the overall gear ratio in your truck and zip along the highway using lower rpms. That change more than any carburetor you will ever find on the face of the earth will positively impact your driving economy. In my case, at 60mph my engine is rotating at around 2000 rpm. Maximum torque and good efficiency. With the stock rear end/transmission my engine would be rotating at around 3000 rpm at the same speed. 3000 rpm is 50% faster than 2000 rpm. Not max efficiency in any way. In fact at 3000 rpm I am well into what I call the "inefficient frontier."
The YF3200s was the last carburetor Carter engineered for the 235. Either that one or the 2100s will be fine for your 235...just depends on whether you're set on having a manual choke or whether you are happy with an automatic choke. Either of those two carburetors will be about the same regarding efficiency, although the 2100s was designed to run richer at lower speeds (in town driving), so your in town mileage may be a bit less. Good luck. We've been talking a lot about gear ratios here lately. Might be some interesting reading.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
The YF2100s is popular around here because it has a manual choke. That carburetor was designed in 1953 (or 1952 for the 1953 235). The 235 changed notably in 1959. If economy is what you want, the engine you have is a very good candidate, but just changing the carburetor isn't the whole answer. You can read about what GM did on their Heritage Pages. Essentially they went with hydraulic lifters and a camshaft that produced greater torque at a lower rpm. Doing this achieved an impressively long flat net torque line. Take a look at page 59 of this report:
The net torque reaches almost maximum at 1600 rpm and stays flat almost until the net torque line and net horsepower lines intersect (around 2600 rpm). At 2000 rpm your 235 is producing as much torque as it will produce. It is not common to find a torque line like that...almost 1000 rpm at more/less max net torque is neat. From the standpoint of economy, this has a message. It means you can lower the overall gear ratio in your truck and zip along the highway using lower rpms. That change more than any carburetor you will ever find on the face of the earth will positively impact your driving economy. In my case, at 60mph my engine is rotating at around 2000 rpm. Maximum torque and good efficiency. With the stock rear end/transmission my engine would be rotating at around 3000 rpm at the same speed. 3000 rpm is 50% faster than 2000 rpm. Not max efficiency in any way. In fact at 3000 rpm I am well into what I call the "inefficient frontier."
The YF3200s was the last carburetor Carter engineered for the 235. Either that one or the 2100s will be fine for your 235...just depends on whether you're set on having a manual choke or whether you are happy with an automatic choke. Either of those two carburetors will be about the same regarding efficiency, although the 2100s was designed to run richer at lower speeds (in town driving), so your in town mileage may be a bit less. Good luck. We've been talking a lot about gear ratios here lately. Might be some interesting reading.
I do plan on changing the final drive numbers, with either a rearend change ,or going to the T5 transmission.
Ive been conversing with Lugnutz on both of those options. He told me if my engine runs good, I could drop down in the low 3's on my rearend gear without any issues. It does run good and I expect it to get better with a rebuilt carb and replacing all the old ignition system.. The Eaton rearend is still in the truck with the 3.90 gear. I believe my only option on it is a change to 3.38. Thats a difference, but not a whole lot.
The T5 I have is still in my 89 S10 for now.
1962 C10 with a 235 6cyl -- all of the drive train seems to be original. Some of this story is in the Side Lot Some people like a new truck. I liked the old ones.
Have you figured a highway mpg with your setup, Jon?
No. It isn't easy to say because the variables that affect gas mileage can either have a slight effect or a dramatic effect. With the AD truck you have to take what you get. Wind, hills, running the A/C, driving over 60, tire pressure, windows down or windows open all impact mpg. Even running the wrong spark plug will make a difference. This coming fall I'm going to get serious about that question and account for all miles driven, all conditions and come up with an honest overall average. I could tell you driving from Texarkana to Dallas (flat as a pancake in a zone where the wind will normally be at your back and on a day when no A/C is needed and driving 55) it is possible to get between 17 and 20 mpg, but driving from Dallas to Abilene will be a different story.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
Interesting. I kinda figured 15 mph would be about best case….even with the improved gearing.
Going from memory, but I think Cosmo used to report 20ish mpg with his highly modified setup. (Dual carb 261 and an OD?)
Wind resistance and fuel distribution are not going to favor a 235-powered AD truck. A guy can probably make some marginal improvements on the fuel distribution. Not much of anything on the aerodynamics.
Good carburetion is fuelish hot air The most expensive carburetor is the wrong one you attempt to modify. If you truly believe "one size fits all," try walking a mile in your spouse's shoes! The Carburetor Shop
W/r/t "until the net torque line and net horsepower lines intersect (around 2600 rpm)"
Those values always intersect at exactly 5,252 RPM. The scale readings are not equal: the HP (left side) scale values are half of the torque in lb/ft. (right side) values.
Best mileage tip: reduce your cruising speed. That truck is a barn door aerodynamically, and above 30 or so mph even 5 mph makes a huge difference.
Aerodynamics makes a HUGE difference!
Dad bought a 1968 truck (that I still have) with one of the bug deflectors fastened on the front. Removing that bug deflector was good for a little better than 1 and 1/2 miles per gallon!
Jon
Good carburetion is fuelish hot air The most expensive carburetor is the wrong one you attempt to modify. If you truly believe "one size fits all," try walking a mile in your spouse's shoes! The Carburetor Shop
Best mileage tip: reduce your cruising speed. That truck is a barn door aerodynamically, and above 30 or so mph even 5 mph makes a huge difference.
I like to describe it as driving a brick through the air. But barn door is a good description too.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
I once strapped a set of plastic patio chairs to the top of my wife’s RAV4, which normally got around 26 MPG on trips. When we needed to stop for gas way before we anticipated, I thought there was something drastically wrong with her vehicle. The mileage dropped to 16 MPG. Once I removed the chairs on the return trip, it returned back to normal.
Last edited by Phak1; 05/23/20237:38 PM.
Phil Moderator, The Engine Shop, Interiors and Project Journals
1952 Chevrolet 3100, Three on the Tree, 4:11 torque tube Updated to: ‘59 235 w/hydraulic lifters, 12v w/alternator, HEI, PCV and Power front Disc Brakes Project Journals Stovebolt Gallery Forum
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