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CHEVROLET Carter YF carburetors.

There have been a number of questions on this and other forums concerning replacing the older Carter type W-1 carburetors and Rochester type B carburetors with Carter type YF. Some have had great success; others less so. This post is an attempt to clarify.

The enthusiast will encounter two major issues with using YF carburetors. The first is the selection of the carburetor; the second is selection of the rebuilding kit to rebuild the carburetor.

Discussing the carburetor selection first: Carter made hundreds of type YF carburetors beginning in 1950 on up through 1986. These were used on applications from Jeep 4 cylinders with 134 CID to Foorrdd 6 cylinders of 300 CID. It is IMPORTANT is use one of the YF carburetors designed for Chevrolet. These carburetors come in 4 groups by size and choke type. The sizes are S.A.E. size 2 which is an inch and one-quarter carburetor with center to center stud spacing of two and eleven-sixteenths inches; and S.A.E. size three which is an inch and one-half carburetor with center to center stud spacing of two and fifteen-sixteenths inches. The two choke types are manual and automatic (when installing a carburetor with automatic choke on an engine which originally had a manual choke, it is necessary to fabricate a “heat stove” to affix to the exhaust manifold).

A listing of Carter YF for Chevrolet

756S size 2 auto choke (1937 and newer engines)
787S size 2 manual choke (1937 and newer engines)
788S size 3 manual choke (1950 and newer engines)
789S size 3 auto choke (1950 and newer engines)
964S size 2 manual choke (1937 and newer engines)
965S size 2 auto choke (1937 and newer engines)
966S size 3 manual choke (1950 and newer engines)
967S size 3 auto choke (1950 and newer engines)
2008S size 2 manual choke (1937 and newer FLEET economy engines ONLY)
2046S size 2 manual choke (1932 – 1936 engines ONLY)
2100S size 3 manual choke (1950 and newer engines)
2101S size 3 manual choke (1950 and newer engines)

The issue with the aftermarket rebuilding kits is quite simple. The carburetors made for Chevrolet were made in the 1950’s and early 1960’s. Most of the YF production was for Foorrdd engines, especially the 300 CID 6 cylinder which require more fuel. MOST (not all) of the current aftermarket repair kits contain a fuel valve designed for the Foorrdd engine which has an orifice of 0.101 inches. The fuel valve as used in ALL of the YF carbs for Chevrolet had an orifice size of 0.081 inches. If you do the math, the valve for the Foorrdd has an orifice size which is seventy percent larger! Using this valve in the Chevrolet carburetor will cause at best an over rich condition at idle, and at worst flooding and fuel leakage.

Jon.

Jon,
Very interesting! However, at the risk of running it into the ground, I will pursue it further.... What is the difference between the following:

788S size 3 manual choke (1950 and newer engines)
966S size 3 manual choke (1950 and newer engines)
2100S size 3 manual choke (1950 and newer engines)
Also, what does the prefix "Z" mean?

Thanks - Scott

Scott - each succeeding higher number superceded the lower (minor design changes). The higher number would be the most desirable, but all are excellent. The "Z" prefix is short for "Zip-fit", Carter's terminalogy for a replacement unit.

There were also some much newer YF carbs made for Chevrolet 6 cylinders in the mid-1960's, but these are not included in this list. The carburetors listed are for Chevrolet 181, 206, 216 and 235 CID engines beginning in 1932.

Jon.

I've got a pair of YF's on an Edelbrock manifold on my 50 216 and after a little tinkering they run great. No hesitation, fires right up with a little choke, even at about 20 degrees, and best of all don't leak like the Roch's. I'm very happy with them.

By the way, the rebuild kit at Carquest Auto Parts stores is their # 121A. It covers about all of the YF's from the looks of the instruction sheet and if I remember right was about $16.

brjr51,
Thanks for the tip, but I hear there is a guy that sells the kits with high quality parts and an uncommon spring that holds the internals together when you hit bumps. It also comes with good instructions and a very informed person on the other end of the line. My son found him on the jeep site, but I think he may be on this BB too. In fact I think he is very close! - Subtle Scott

Question in another thread, so placing an entry here to return this thread to recent postings.

Jon.

What about the GMC motors? Did they also use Carters in the later years?

Jon, are the YF carb identification numbers cast or stamped on the carb body ?

Jon, I recently installed a 'rebuilt' YF on my 235 and although it seems to run fine and doesn't leak, I have to start it without any choke. After it starts if I choke it very little the engine will die. After it warms up it seems to run fine and acceleration is great compared to the old Rochester. But, I think I may have some problems getting it going in cold weather. Is this indicating the wrong size (as in too large) fuel valve? If this is the case, are fuel valves of the correct size available without buying an entire kit?

Your sharing of information on carburetors is very helpful on this board as it seems a lot of us like to play with our carbs. I am getting old enough now that sometimes I think I would like to get mine set right and leave it alone. Thanks- Doug

Splashoil - the true GMC engines used mostly Zenith and Stromberg carbs, and excellent carbs they are.

Rusty46 - most of the aftermarket Carters have the number stamped (not raised) on the center section.

Pete - it is possible you have a problem with idle adjustment. Give me a call during normal business hours to discuss.

Jon.

I've run two YF on my 39 GMC for years on a Nicson
The real problem is small parts
I've basically run the same carbs on both the trucks engines 228
and 302
But where do I get the small bits?
I'd really like to fine tune these instead of relying on their flexibility

I've both off now after the 39 started popin and fartin and I traced it to clogged carbs....

Nate has em cookin in some trick Yamaha stuff

Carbking,
Thanks for that list, it is very helpful. But I have a like new YF 820SB What is that from???
Chevyb

Thanks Jon, I appreciate the information and knowledge you share with us.

Always good for a refresher...ttt

Does anybody have an idea what Carter Yf will fit on a 1962 261 cid and if the bolt pattern is the same as the 235 from 1954 the intake I have is for an 235 cid it will fit the 261 but the 261 used larger Carburetors than the 235

Robert

Welcome to the board! There is a TON of useful information here! Fire up that search engine and find an answer to just about anything!

I don't believe that Carter made a YF for the Chevrolet 261 engine. If you don't want to use the original Rochestor, then I suggest a Zenith series 228. This is the carburetor that was used on the GMC 270 engine. It's CFM rating makes it a better choice for the 261. You certainly can use a YF carb for the 235 on your 261, but your engine will not live up to it's full potential. I used a YF2100 on my 261 for a while. It was thoroughly adequate.

I'm now using the Zenith 228 carburetor on my '54 261, and have no complaints. It was a direct bolt-in with no modifications needed to the linkages.

However, it can be a somewhat hard carb to find. I was fortunate and found mine on ebay for dirt cheap. I had a local carb guy professionally rebuild it.

Happy 'bolting to you!
Steve

Carter did not offer a carburetor for the 261. For best results on the 261, use either a Zenith 28 or 228 for the GMC 270 (as previously posted) or one of the Stromberg "B" series replacement carbs. Both work very well.

Jon.

Carbking,

There are Carter YF's for sale on ebay, but most of them have an automatic choke. For example, there is a 789S w/Auto. What's necessary to fabricate a "heat stove" to the exhaust manifold, and can these auto chokes be converted to a manual choke?

Thanks
Dave

NAPA has an automatic to manual conversion kit. Price is about $75.

To fabricate a heat stove:

(1) acquire a 6 inch by 3 inch piece of sheet metal
(2) cut a 1/2 inch square out of each corner
(3) bend up all 4 sides
(4) you now have a rectangular bowl 1/2 inch deep
(5) drill a hole in the center of the bowl
(6) insert a brass fitting in the hole

Heat stove is finished. Install with the open end of the bowl toward the exhaust pipe (or manifold), and attach with muffler clamps. Bend a steel line to attach the brass fitting on the stove to the choke on the carburetor.

Jon.