2GC carb on merc manifold

[FordyOne]

I'm planning a 2gc carb for my 8ba. Is the heat riser still necessary?

[tubman]

I believe so. I am running a couple of them, and as has been said before, if you mount them backwards on the manifold, the throttle and fuel lines literally fall into place. However, the choke ends up on the wrong side and operates backwards. After a lot of looking around and thinking about it, I came to the conclusion that running the Mercury automatic choke is the best solution. Mine work flawlessly. For the automatic choke to operate properly, you need the heat risers. I see you're in Michigan, so blocking them will also effect driveability in the spring and fall.

You should also know that Mercury used two types of automatic chokes in the late flahead era. First, there are "regular" chokes where the choke mechanism is on the carburetor and is connected to the heat riser by a hollow tube. The second type has the choke mechanism mounted on the manifold and connected to the actual choke plate itself by a rod. These are known as "divorced" chokes. It all depends on the year Mercury manifold you pick up. I have done 2G setups with both types of chokes, and all that is needed in either case is a slight bending and shortening of the tube or actuating rod. Lucky for us that GM made 2G carburetors with both types of chokes as well; a "2GC" has the "regular" choke mechanism mounted on it, while a "2GV" is used with a "divorced choke mechanism. (Manual choke Rochesters are simply "2G".) You will be well served if you obtain the carb and manifold each with the proper choke type.

I have been a manual choke guy all my life, but the Mercury choke mechanism matched so well with the 2G that it was just too good to ignore.

[FordyOne]

I had been considering an electric choke. Anyone had any experience with them?

[oldbugger]

I have an electric choke on my 35 with 53 merc engine, been working great. Not sure if I can post pic but I'll try.

[tubman]

Sounds like an interesting (but unnecessary) exercise. Let us know how it turns out.

"old bugger", was that with a 2G type of carb or a Holley 4-BBL?

[oldbugger]

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Yes 2G I have pics but I'm not smart enough to follow the posting directions. Sorry

[V8COOPMAN]

Originally Posted by oldbugger

Yes 2G I have pics but I'm not smart enough to follow the posting directions. Sorry

"bugger" ..... A little bit of "deja vu" involved here once again. If you'll e-mail 'em to me, I'll post 'em for you.

My e-mail: [email protected]


Included BELOW is the link for that tutorial that I wrote-up a while back for posting pictures. Click on the link!


https://www.fordbarn.com/forum/showp...&postcount=649


Coop

.

[oldbugger]

Thanks so much for posting the pictures for me. I guess I'm not very quick, I thought I followed your instructions, still no luck

[FordyOne]

Tubman, I checked my 2GC and it is the type with the vacuum tube. I don't know how fussy I can be about finding the correct manifold, they don't come up so often anymore so I that is why I am thinking electric or manual. I'm comfortable with either.

[FordyOne]

oldbugger,you could almost make paper airplanes out of those pictures and throw them to me .I 'm just east of South Haven.

[51504bat]

IIRC the Merc manifold needs to be machined to match the 2G card. I think there was a thread on it either here on on the HAMB.


Edit:
This is from the HAMB
https://www.jalopyjournal.com/forum/...ntake.1205124/

[oldbugger]

Im just north of Saugatuck. send me a pm and you can come over and look

[tubman]

Originally Posted by 51504bat

IIRC the Merc manifold needs to be machined to match the 2G card. I think there was a thread on it either here on on the HAMB.


Edit:
This is from the HAMB
https://www.jalopyjournal.com/forum/...ntake.1205124/

The 2G throttle bores are 1 7/16" while the Merc manifold has 1 3/8" throttle bores. To get the best performance, the Merc manifold should be bored out to the 2G size. I do this with a device called a "Rota-Broach" and bore the manifold all the way down. I have done both aluminum and cast iron manifolds, and the "Rota-Broach" cuts both easily. I have a guide I made out of a 1" block of aluminum that I bolt to the carb mounting surface. I then bolt the manifold to my drill press base at the correct angle and run the broach down. Because of the depth of the cutter, the cutter is self-guiding. It's not a difficult task. The "Rota-Broaches" are kind of expensive, but I could be convinced to rent mine out. Here's what they look like :

[FordyOne]

51504bat,are you the guy who has the merc manifold in the swap meet ? If you are I would be glad to buy it . I would have contacted you there but don't have 10 posts . Been here and the old Bill Bentley site for 25 years and don't have 10 posts yet.

[alanwoodieman]

running a 2cg on my 51 merc engine in my 41 truck for over 10 years and I have a proper working manual choke. small bore 2gc are no problem, big bore 2gc will interfear really badly

[V8COOPMAN]

Originally Posted by oldbugger

Thanks so much for posting the pictures for me. I guess I'm not very quick, I thought I followed your instructions, still no luck

Here are the pictures I promised to post for "oldbugger".


Coop

[FordyOne]

oldbugger,between your pics and alanwoodyman's I have a good idea of both manual and electric options. If I decide to go electric I may take you up on that visit.

[miniceptor86]

I bored my Merc manifold on a bench type drill press and an inexpensive hole saw. I used the the 2gc base gasket to mark the new holes which are offset from the manifolds original bores. My Merc manifold had provisions for the choke heat tube. The auto choke works flawlessly. I got my 2gc from RockAuto but had to send it back to the remanufacturer (UREMCO, great people to work with ) because the motor didn’t run great. They found “dirt” still in some air bleed circuits. Even though it was a rebuilt carb the float level was not correctly set as well as the choke fully closed gap.

[FordyOne]

Thanks, Jim, that is a good idea I have a friend who is a machinist with access to a shop he uses after hours. And, this post is my tenth, so I may be able to PM now.

[miniceptor86]

I have some pictures in my photo album on this forum.