Howdy. Stock 390 with a stock '62 Caddy intake. Trying to run an Edelbrock Carter-style carb, I want to say it's 500 cfm. Idles rough and off-idle rough, stumble "spit-n'-quit". I'm guessing the trough on the intake plenum carb casting is either part of the idle circuit or for heat riser? Somebody plugged the holes at some point in time (not me). Anyway, I'm thinking carb/manifold mismatch or vacuum leak is causing it to lean out. I can't find any apparent leaks around the manifold. Is there any way to get the Eddy and Caddy to play nice together? I also have a square-bore to spread-bore spacer on there. Thanks!!
The original Carter was a 650 CFM, and calibrated SPECIFICALLY for the Cadillac 390 engine. Carter 3351s W/O AC Carter 3352s W / AC Jon
Unfortunately, I don't have the original Carter, otherwise I'd use it. I do have another Edelbrock 650 CFM I could put on there. But I guess the flow of the OEM intake is just that picky?
The bases on those carters are cast iron I''m not sure how well an aluminum carb base will handle that heat. I have drilled and tapped and plugged the holes that let exhaust heat in a Chevy intake that had that heat channel in it and ran it for years that way.
Edelbrock carb will bolt to the 390 intake. No adaptor needed. Should tap heat risers for 1/8 pipe plugs. An off the shelf 650 E-brock carb is probably jetted a bit lean for the 390.
I've never seen a Carter AFB that wasn't all aluminum. People who discarded the stainless steel plate that went between the intake manifold and the carb ended up warping and/or corroding the aluminum carb base.
"I've never seen a Carter AFB that wasn't all aluminum" AFB stands for Aluminum Four Barrel... Marketing genius, I tell yuh!!
I think I have a line on a rebuildable 3352s. Was there originally a spacer between the carb and manifold, or does it bolt directly to the manifold?
There is a THIN (maybe 0.020) plate between the carb mounting gasket and the intake to block the exhaust coming through the intake to warm the carburetor. Carter part number is 186-93. As far as I am aware, these have not been reproduced. I checked out inventory, and we have been sold out for maybe 40 years. One could be cut out of a sheet of stainless without a lot of trouble. And it would not be airflow that would be the problem by using the clone, rather calibration. Figure on primary jets, secondary jets, step-up rods, step-up springs, an auxiliary air valve, plus machine modifications to the primary clusters. As far as I am aware, ALL Carter AFB carbs fit into the "square-bore" category. Yes, many of them have secondaries slightly larger than primaries; but not the 1.375 primary, 2.25 secondary of the normal spread-bore. The largest spread on the AFB's were 1.0625 primary, 1.5625 secondary. These still classify as square-bore. Jon
That is very important and helpful information; thanks very much! I've got a nice, complete and original 3352s on the way to me with the A/C dashpot. So I am****uming that no mods need be done since this is the correct carburetor, just a rebuild kit (?). I think I still have a paint can of Berryman Soup somewhere...
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