Okay, I know the four BIGGER holes are for the throttle plates, folks...but what about the two smaller holes on each side of them (next to the four throttle holes)?? The intake is from a 1960s small block Chevy, likely topped with either a Carter or a 4-jet originally. Should these holes be plugged to run an Edelbrock?? I've never had one of these old cast iron intakes before, so it's new stuff to me!!!
Close, they are for the heat passages...the carb has a cast iron base, with a passage that runs around the front connecting the two side holes. Takes a special base gasket. You could plug them if you don't run the original carb.
Allows hot air from the exhaust x-over to heat the bottom of the carb area for quicker warmups/better atomization of fuel in cold climates. Plug for "performance" in warmer climates
heat riser i believe,ive had early cast 2 barrel intakes that had them,ussualy on the 2 barrel intakes the carb studs would break off
Thanks guys... I was thinking they had something to do with warming the stock carb up (since they go into the exhaust crossover), but did not know that the original carbs had cast iron bases on them! They'll be plugged for sure!!!
I asked because he snaked it off my shelf at my "going away party". It's out of my 64 Impala SS, the stock intake for a 327 4 bbl. I think it had a Carter originally, but when I got it it had some bastard style Holley, and IDK if a "regular" (1850/60) Holley will fit or not. Jay
Yup, those are heat riser holes. Tap them out and screw a plug into them. They ran a sort of high tempreture gasket to insulate the carb base. Usually age makes them crack. I've tapped a couple of them for 1/2" bolts, then drilled and tapped a hole in from the outside and put in a set screw just to keep things from moving around. Just put a coat of high temp RTV on the bolt threads to take up any slop, lock the set screws and it's done. I've never had any issues with leaks after doing this.
Mid 60s Chevy used a strange base on Holley carbs on some models, that covered those holes. A standard Holley will have a vacuum leak at that point, unless you use two gaskets and a seperator plate.
Some clown boogied outta Michigan and left it behind!! Edelbrock used to sell a thin metal plate that they recommended for use on the original Performer intakes when running a square-bore carb instead of a spred-bore one (the manifolds would accept either). That plate (with two gaskets) would probably do the trick here like you mentioned, but in addition to that, I'd feel better blocking the holes as well. Thanks, All!! (You too, Jay!! )