4 bolt and 2gc

47 flatbed

47 flatbed

Senior Member
Looking for the prep work needed to make this work. Intake is cast.(hersery find 2 years ago) 2gc with electric choke. Is there any plugs or areas that need to be adressed with the intake. I also left a message at Bubba's for an igintion. Thanks in advance.
Mike
 

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I have this set up, but I haven't tried it out yet. The fellow that sold it to me said the following "When I used a Rochester carb on an old Merc intake, I first used a Merc
> gasket then a metal plate (that matched the bottom of the Rochester carb)
> and then a Rochester carb mounting gasket."

Thought that might be helpful. I think there is a small hole in the side of the intake for a choke tube or something. That would probably need to be plugged.
 
Here's what you need to know. The small base 2GC came early on GM V-8's and some V-6's ('50's - 60's). As I said before, the small base carbs bolt right on to the Merc manifolds (as GreenMonster48 said, there are some open passages in the bottom of some 2GC"s that may require an adapter/block-off plate). If you mount the carb backwards from it's usual orientation, the throttle linkage and fuel lines drop almost exactly into place. Unfortunately, this puts the manual choke linkage on the wrong side of the carb with a backwards pull. I have an aluminum later model Canadian Merc manifold with provisions for an automatic choke. On this set up, the choke tube is on the proper side of the manifold, and the choke tube mated to the 2GC with a minor bending.

As to a cast iron manifold; it should work as well as a Canadian aluminum on if prepped properly. I used an aluminum manifold because I figured it would be easier to bore. I purchased an arbor and a 1 7/16" cutter from an outfit called "Rotobroach" (or perhaps Rotabroach - hyphens optional). The bad news is that the cutter and arbor cost almost $100. The good news is that it worked so well on the aluminum, that I think it would work well on cast iron. I did mine with the manifold clamped on my benchtop drill press and had no problems at all. I used a spare 2GC base as a guide to keep the cutter centered. This method has the advantage of putting the bores in the manifold exactly the same as the carb.
 
I'm still in the setup phase too. As GreenMonster said it will need an adapter plate to support the back of the carb which overhangs the manifold. The carb will seal without it but there isn't good surface bearing to tighten the nuts. the two 1/8" holes where the old choke actuator sat will need to be plugged. I'm pretty sure the bigger crossover tube can be left open on pass side. I don't think it is open to exhaust gasses.

Lonnie
 
I run an 8ba in my 41 truck with a 2GC carb from a V6 buick engine used in a 66 Jeep, 4 bolt Merc intake, carb mounted back ward, adapterted to throttle/choke, used the dash throttle hole for the chock rod, did not need throttle rod, seems to work in SC with no problems. I also used a 2GC off a 307 chev, changed out jets to make it work, used as my spare now.
 

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Mike, make sure the holes in the throttle base near the front mount holes are plugged as well as the vacuum signal port on the back under fuel inlet

Lonnie
 
What sort jetting are you lot using in the 2g on a flathead? How do they compare to a 94 or 885 Economy and power. On the original 8CM the choke pulled exhaust warmed air through the exhaust heat riser. What did the 2g use for its choke? Was it exhaust warmed air, or actual exhaust gas? I ask incase someone wanted to run the stock 2g choke?
Many thanks.
Martin.
 
Using the 2GC on a merc or Ford intake the throttle bores are smaller. Using a die grinder you can blend in the interference areas. However to take advantage of the increasec AF flow of the 3G it best to bore the intake to match the carb, or why use it in the first place. The open bace of the 2GC can be willed with JB weld and the center hole drilled for the ford mounting can be drilled through the Vacuum port for the carb, thus mounting it on a ford intake. Using an AF meter is the best way to tune it, especially if running a hot cam. you may have to cut some coils from the PV spring. This is a great carb and provides excellent power and economy when tuned properly. Remember it needs the SBC dist to run right
 
Hello Ron,
I'm fiddling here with an 8CM manifold and carb (885) and a Rochester 2g. Both these carbs here have the same throttle bores, both are also bigger than the holes in the manifold. Makes me wonder if the 885 with the opened manifold might be another good choice.
Do you know what the 2g used in it choke heat, warmed air or actual exhaust?
Thanks,
Martin.
 
I am using the 2g on my 53 merc engine with good results. I solved the choke issue with electric choke setup, 12v, works great. easy to hook up pcv valve also. need the gm dist. good luck
 
47 flatbed said:
Basically there is little to be done besides a plate between intake and carb?
Click to expand...

Seems that way, use the plate for carb support, mount the carb arse about face to make the throttle linkage easyer. Sort out choke, which ever way you fancy. Seems stock jetting is good to go, or at the least a good starting point to tune properly.
All good info thanks all.
Martin.
 
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