So my 66 buick electra has its factory Rochester 4GC carb. I've been told that it is very restrictive and I need to change it out. I was wondering is this true? Also what can I do in order to get more power out of my 401 nailhead engine?
What do you want out of your car? I had a 4GC Rochester on my '64 Chevelle SS and got it up to 120 MPH, with a 283 (added the carburetor and manifold- this was not a stock option, but the rest of the engine was stock). Your car is heavier, so may take longer to get to that speed, and having a larger frontal area may not reach that speed. If you are looking for acceleration, and don't cruise the highways for long drives your best bet would be to just put in a lower gear ratio rear end ring and pinion. There are options for the 401, like a dual quad manifold and carburetors which will only give you a small boost in performance, since the cam and pistons will not match the flow available. Plus, those parts are on a par with gold for their cost. That carburetor is actually matched to your engine from the factory. Once you start changing things, it's going to be cubic money.
Yeah , what Steve said . If you want to cruise around - good basic carb rebuild , good full tune up , lower restriction mufflers/dual exhaust and make sure that your brakes and suspension are properly set up . Enjoy the ride . You have a part number for carb and/or a couple pics ?
The 4GC is a tough carb to keep fresh these days. Some parts, like floats are no longer made. There were 3 cfm sizes for the 4 jet. 486, 553, and 692. The early Quadrajet offered 750 cfm. I agree with the above info. If it is a cruiser, enjoy what you have and cruise.
Right now it's single exhaust with a long glasspack welded to the end of the pipe ending at the axle.
I picked up .4 of a second and 4mph in the quarter mile changing from single to dual exhaust on a '70 cutlass 4 door 350 2bbl. Also consider recurving your distributor professionally. Your car may want different timing requirements from the factory specs. Carbs respond to vacuum signal. If you have the original nylon timing chain in it, I replacing it for piece of mind. Good luck
You have a glass pack at the end on top of the muffler? I would take that off and run a straight end exhaust. Any extra breathing to a Nailhead helps especially dual exhaust but I don't know if the single exhaust manifolds are different and can work. Maby someone will chime in on that. I would change the 4GC to a at least 650 AFB or it's Edlebrock equivlent..as finding a Q-jet manifold would be very expensive. Use a after market air cleaner if your still using the original. "Save the original" What's the weather out there, just curious?
Thanks for that bit of information. I'm not worried about the carb right now but I do want to change it out in the future. I also plan on dual exhaust. I got quoted $280 for true dual exhaust. (Do you know what mufflers sound best on a nailhead?) I would've gotten the exhaust done months ago if it were not for the car needing work every time I turn around.
Nope the glass pack is my muffler. The original muffler fell off one day when I was driving through town! I drove the car straight piped for 2 months before I got tired of the sound. Also it's starting to warm up here in Booneville, Mississippi. It's usually humid. Some days more than others. And yes I'm still running the stock air cleaner. I've been wanting to change it out for a round air cleaner but I haven't found a cheap one. (Once I get the car reliable I can start buying goodies for the car. A cheap one will do for now.)
