The Stovebolt Site Forums The Shop Area Engine Shop Rochester to Carter Carbs

On replacing Rochester Carbs to something else, I guess the standard practice is to use the existing insulator/spacer from carb to manifold. The Rochester throttle body flange has one port which the spacer accomodates and well as replacement gaskets. Now the Carter YF has two ports on the flange the the insulator/spacer only mates up to one of them. Also all the Throttle Body gaskets that I can look at all cover up that second port. I am running twin YF single barrels. Has anyone experienced leaks at the base? Should both ports be open?
Help.

No leaks. Been running my YF's for years. Best thing I ever did getting rid of
those leakchesters!

Easy question!

When placing an aftermarket (or different to original) carburetor on an engine REGARDLESS OF BRAND, ALWAYS USE THE CARBURETOR MANUFACTURER'S SPECIFIED GASKET!!!!!

For Carter type YF carbs used on early Chevrolet 6 cylinders:

Carter 1A-24 (use with governor only) 788s

Carter 1A-31 788s (w/o governor), 789s, 966s, 967s, 2100s, 2101s

Carter 1A-41 756s, 787s (w/o governor), 964s, 965s, 2008s, 2046s

Carter 1A-59 (use with governor only) 787s

Using these gaskets will assure that the carburetor gets all the vacuum it needs. Next make certain that the specified gasket will not leak vacuum externally on the intake (or spacer).

Jon.

The original insulator/space covers one of the two vacuum ports on the TB Flange. Should this insulator be ground out so it can access engine vacuum?

If you use a gasket with the appropriate cut-out to match the vacuum hole/port on the base of the carburetor, the carburetor to intake manifold insulator does not necessarily need a notch in it.

Okay. Assuming the correct gasket, the spacer seals the path in the proper gasket. There is not "canal" from the spacer to the throat that allows passage of vacuum to the carb. Am I missing something?

Are you using a spacer?

Actually, yes.

Please note in my previous post the different Carters that were designed SPECIFICALLY for early 1950's Chevrolet. The are dozens of later YF's designed for Chevrolet, and HUNDREDS of additional YF's for other applications.

The safe way is to use the carb specified for the specific application AND the specified gasket. If this is not done, then you need to know WHY the passage is in the carb. Some carbs were designed to provide a manifold vacuum port, others a ported manifold port for distributor use. Others were designed to have a passage to provide vacuum to a sandwich governor. Sometimes a passage would be used for dual purpose if the casting were used on different applications. And then you always have to contend with Dr. Goodpliers (the evil twin of Mr. Goodwrench) who thinks castings may be interchanged among carburetors.

When using other than factory engineered parts for the application, one becomes ones own engineer. One can always disassemble the carb, and determine the origin (or the object) of the passage.

So while your question about notching the spacer is a simple question, there is no single answer because of the different applications.

As stated in my first post, if you use the specified gasket for the carb, then the carb will get all of the vacuum the carb needs without providing any other help. Now whether you get the desired distributor vacuum, governor vacuum, etc. depends on the application.

Jon.

Thanks Jon. I have twin YF2100S Carbs on an Offy manifold. I understand Proper gasket for Proper Carb. You advised the proper gasket for the 2100S series is a Carter 1A-31. I can't find any pictures of what that looks like. Do you have any?

We don't sell individual gaskets (they are contained in the repair kits we make); so, here is a picture:

http://www.thecarburetorshop.com/Carter_Chevrolet_YF_flange.jpg

Jon.

I need to take a picture of the bottom of my carb, the gasket, and the insulator and share.

None of the holes lined up the way it seems they should, so I modified the gasket in a way that made sense to me to get vacuum to the hole in the bottom of carb. Now I'm curious if I did it right.

Okay, thanks for the picture. It looks like one of the ports can be covered.

Here's a pic of what I described earlier. Insulator - Carb - Gasket

My assumption is the little hole in the base of carb need access to vacuum.

But that hole does NOT line up with the notch in the insulator, nor the hole in the gasket. (Incidentally, the hole in the gasket does line up with insulator notch)

So, I made a notch in the gasket that lines up with the hole in base of carb. Will that work?

Either this gasket or this gasket should do want you need.

Unfortunately, they are not labelled correctly with respect for years and for sizes of engines.

From what I have figured out, if you use the proper gasket for the proper Carter (Carbking) then mate it to the old Rochester Spacer, nothing lines up. It seems the Carter gasket is meant to keep at least one flange port open to vacuum. I traced both of my ports and they go to the same plenum so I assume you only need one. Then you put on the Old Spacer and it covers up the port that your proper gasket uncovered for you. Then no vacuum is getting to the main body plenum. So is seems to me that Carter should have made a spacer for their replacement Carbs.

Thanks. Looks like same part number both links?

Sorry, I have changed one of the links above.

There are two gaskets - both with cut-outs that go the "throat".

The two diameters are for the two diameter holes/bases in the different "generation" carbs/manifolds.

I have a 235 sized carb. See how the one they label as 216 has the cutout very near the mounting bolt hole? That's where mine "needs" to be, as opposed to the gasket they label as 235 has the notch further away.

What year 235 carb?

235s were used from 1941-1962/63.

I think the same intake/exhaust manifolds were used on both 216/235 engines through 1949.

The carburetor hole-diameter in the intake manifold changed in 1950, from then onwards, the 216 & 235 engines had different intake manifolds. And, they had different carburetor base sizes, and different carburetor mounting bolt distance/separation, and different carb-to-manifold gaskets.

The correct size carb-to-intake gasket should be used.
A gasket with a cut-out in the correct location should be used.
A gasket without the cut-out could be cut out (by the installer) in the correct location.

Just to complicate things (or, just to make things easier for mechanics/shops), I think that some carb-to-manifold gaskets were made to work on both size manifolds (and in any orientation).

I have a collection of carb to intake insulator plates/spacers (and gaskets). Some have little indentations in the "cut-outs" locations, and some do not. I use the appropriate size insulator/gasket (for the intake hole diameter, and attachment bolts) - and make sure the slot/cut-out/hole in the gasket matches the hole in the base of the carburetor. Some of the extra cut-out holes in the gasket will serve no purpose (but, will cause no problems). Some of my gaskets have no holes - presumably used by some people between the insulator and the intake manifold? I usually put no gasket in that location, unless there is a vacuum leak when using no gasket.

Yeah, mine is the large base 2 - 15/16 carb. I guess I will just stick with the one I modified to fit the carb hole. Should allow for some space even though it doesn't match the insulator notch.

Getting ready to try a restart after installing a new set of manifold and new radiator. Just so I know, what are the symptoms related to that carb port being blocked? Rich running?