8ba 275 carb options

[tubman]

sweet thanks, i should've taken you up on your offer a while back about going into detail about your set up, what do you have for throttle linkage? how did you bore the intake out? just a die grinder or something more precise?

Basically, I just added a ball stud to the 2G that was the same size as the end of the Ford throttle rod, and everything fell together. IIRC, I cut off the end of the Ford throttle rod, threaded it and screwed on an adjustable rod end. Actually the throttle doesn't open quite all of the way, but the increase in performance was enough that I haven't got around to fixing that yet.

I used something called a "Rota-Broach" and a guide I made out of 1" thick aluminum to bore the manifold. I just slip the guide over the carburetor studs, clamp the intake manifold on to my drill press, and bore away. The only tricky part is getting the manifold clamped down at just the right angle because the carb mounting surface is not parallel to the block mounting surface. I have done aluminum and cast iron manifolds and they both cut easily. This method allows you to cut all the way down the manifold a full 1 7/16". When this is done, I use a die grinder to smooth the transition at the bottom of the bore. The "Rota-Broach" and it's required arbor are kind of expensive, but I use the in the manufacture of my "trash can" condensers. I have the cutter and an extra arbor I could let you use (along with the guide) for the cost of shipping if you want. All I would need is a $100 deposit to make sure I get it back. PM me if you're interested.

EDIT : One last thing. The 2G base has voids cast into it for manifold heat. The size and shape of the Merc manifold carb mounting surface is such that these voids can cause vacuum leaks. This can be remedied by using stacked Merc and Rochester carb gaskets. In the alternative, I have made block off plates made from 1/16" aluminum to take care of this. Since it costs as much to make 20 of these as 1, I have spares.

I notice you are in Canada, which may make shipping problematic.

 

[V8COOPMAN]

I use this unit from Speedway Motors or Amazon. On the chance that it might be restrictive, I ordered another element and made a longer center stud and run two elements stacked one on top of the other. It looks good, works good, and still fits under the hood of my '51 with good clearance. (Sorry about using a link rather than a picture; for some reason I can't attach a 250K .jpg this morning after doing it successfully for years.)

https://www.amazon.com/Inch-Chrome-Cleaner-Barrel-Carb/dp/B075NQR3M4?tag=atomicindus08-20

How's this, for a dumb boy?

Coop

 

[tubman]

That's the one.

Thanks, Coop.

 

[Alberta50fordor]

Basically, I just added a ball stud to the 2G that was the same size as the end of the Ford throttle rod, and everything fell together. IIRC, I cut off the end of the Ford throttle rod, threaded it and screwed on an adjustable rod end. Actually the throttle doesn't open quite all of the way, but the increase in performance was enough that I haven't got around to fixing that yet.

I used something called a "Rota-Broach" and a guide I made out of 1" thick aluminum to bore the manifold. I just slip the guide over the carburetor studs, clamp the intake manifold on to my drill press, and bore away. The only tricky part is getting the manifold clamped down at just the right angle because the carb mounting surface is not parallel to the block mounting surface. I have done aluminum and cast iron manifolds and they both cut easily. This method allows you to cut all the way down the manifold a full 1 7/16". When this is done, I use a die grinder to smooth the transition at the bottom of the bore. The "Rota-Broach" and it's required arbor are kind of expensive, but I use the in the manufacture of my "trash can" condensers. I have the cutter and an extra arbor I could let you use (along with the guide) for the cost of shipping if you want. All I would need is a $100 deposit to make sure I get it back. PM me if you're interested.

EDIT : One last thing. The 2G base has voids cast into it for manifold heat. The size and shape of the Merc manifold carb mounting surface is such that these voids can cause vacuum leaks. This can be remedied by using stacked Merc and Rochester carb gaskets. In the alternative, I have made block off plates made from 1/16" aluminum to take care of this. Since it costs as much to make 20 of these as 1, I have spares.

I notice you are in Canada, which may make shipping problematic.

So the performance increase is noticeable with the bigger 2bbl?, how does it compare flow/performance wise to a super dual?
also how do you have your choke set up? I'd rather stick with a manual choke

 

[Ross F-1]

From various sources:
Holley 94. Carb. 155 cfm
Holley 8ba. Carb. 162 cfm
Holley ECG (2110 Y-block) 210 cfm
Rochester 1 1/4" flange ("small base"), 1 7/16 Bore x 1 3/32 venturi = 278 CFM.

 

[tubman]

So the performance increase is noticeable with the bigger 2bbl?, how does it compare flow/performance wise to a super dual?
also how do you have your choke set up? I'd rather stick with a manual choke

It's really hard for me to say. The 2GC is on a good running '51 Merc with massaged Edmunds heads and a Mallory dual point that I swapped in to replace a rather tired stock 8BA. The 8BA ran fine but was always a little weak. I tested the compression before I pulled it and all cylinders were between 85 and 105 psi. The Merc I put in, though used, had 110-115 on all 8. The increase in performance was quite evident.

As to the difference (if any) from a "Super" dual, I really have no idea. If I had to guess, I'd say that the "Super" would have a slight advantage at speed but would be more difficult to get and keep running right. As I alluded to earlier, there is still a little throttle left on my present set up due to the geometry of the linkage. I adjusted the linkage to get full throttle, which resulted in obtaining a full pull at the penalty of a 1500 RPM idle. The increase was not enough to cause me to upgrade the throttle linkage (yet). I think, given the fact that I have a stock cam, ports, and displacement, the 2G is about all the carburetor my engine will take.

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. When run backwards, the fuel line and throttle linkage need very little change. The choke however, ends up on the wrong side and pulls backwards and is just located awkwardly. I have done 2G setups with both "regular" (choke mechanism on the carburetor) and "divorced" (choke mechanism located on the manifold) chokes, and all that is needed in either case is a slight bending and shortening of the tube or acuating rod. As a side benefit, I have now learned how to repair and adjust automatic chokes and have come to love them.