Edelbrock 650 Manual Choke

Getting the Manual Choke Working on Your 650 Carb

The Edelbrock 650 with a manual choke is one of those setups that seems straightforward on paper and then introduces a few frustrating gremlins once it's actually bolted to an engine. The choke isn't a big deal if you understand how it operates, but the wrong approach turns a simple cold start into a 20-minute guessing game involving repeated button-pulling and a soaked intake manifold.

Here's how it works. The carb has a mechanical lever on the driver's side. When you pull the cable, the choke plate closes. That's it. There's no vacuum advance, no self-adjusting mechanism, no computer telling you when to open the plate. You control it entirely by hand. Pull to close, push to open. Simple concept, but the execution is where most people mess up. The cable routes from the dash or a floor-mounted kicker to a lever on the carb. The linkage connects directly to the choke shaft. One important detail that people consistently overlook: the choke needs to fully close and fully open. If your cable is too short or the bracket is positioned poorly, you might only get partial choke closure. That means you're richening the mixture slightly instead of getting a proper closed choke for starting. The fix is usually just trimming the cable housing and re-crimping the outer jacket so you have a few more inches of travel. Takes about ten minutes with a pair of side cutters and a crimping tool. I ran into this exact problem on a '72 Chevy with a mild crate motor swap. The carb was sitting right, the bracket was correct, but when I pulled the cable all the way in, the choke plate was maybe three-quarters closed. The engine would start, but it flooded immediately because the plate wasn't sealing the air horn properly. I traced it to the factory cable being pre-stretched from manufacturing. I cut two inches off the outer housing, re-crimped it, and suddenly the plate went dead flat against the seat. Engine started on the first pull every time after that.

When you route the cable, keep it away from hot exhaust components and moving suspension parts. A melted cable jacket is a pain to replace. Use a loom or split loom tubing if the routing path runs near anything that gets hot or vibrates a lot. The manual choke cable itself isn't expensive — Edelbrock sells replacements for around thirty dollars — but diagnosing a burnt cable at midnight on the side of the road is not fun.

Starting Procedure That Actually Works

Most people treat the manual choke wrong because they're used to vacuum chokes or electric chokes that self-adjust. With the manual setup, you need a consistent routine. Start cold. Turn the key. Pull the cable firmly to the stops, hold it for about five seconds, then release and let it snap back. Do not leave the choke pulled in while cranking. You'll dump raw fuel into the intake and flood the thing every single time. The brief pull closes the plate just enough to enrich the mixture for startup without over-fueling. After the engine fires, let it idle with the choke still closed for maybe thirty seconds to a minute. This gives the fuel enough time to vaporize properly before you introduce more airflow by opening the choke. Then pull the cable again to open the plate. You'll feel the engine RPM climb as the choke opens and more air gets admitted. The idle will smooth out within a second or two. If it bogs down after opening, you held the choke closed too long and the chambers are now too rich. Next time, let it idle shorter before opening. This is counter-intuitive for a lot of builders. You'd think leaving the choke closed longer helps warm things up faster. It doesn't. A flooded engine won't run regardless of how long the choke stays shut. The sweet spot is brief, controlled enrichment, not sustained flooding.

Common Problems and What They Actually Mean

If the choke sticks closed after warmup, the cable is either binding inside its housing or the return spring on the carb is weak or broken. Inspect the cable for kinks or debris. Wiggle the cable while someone watches the choke plate — if the plate doesn't move freely when you push the cable in, the housing is restricting movement. Replace the cable. If the plate moves fine but won't stay open, the return spring inside the carb is suspect. Edelbrock sells a rebuild kit for around twenty-five dollars that includes a new spring. Choke plates that don't seal properly is another frequent issue. This usually means the shaft has wear in the bushings or the plate angle is off. With the carb off the intake, remove the air horn and inspect the plate. It should sit perfectly flat when closed with no visible gap at any point around the perimeter. If there's a gap, the plate is bent or the shaft is worn. A slightly worn shaft can sometimes be compensated by adjusting the plate angle via the retaining clip, but if the play is significant, you're looking at a replacement carb or a rebuild. New bushings run about eighteen dollars at most carb shops. Here's something most guides don't mention: the manual choke on the 650 is sensitive to intake manifold design. If you're running a tall dual-plane manifold with a long taper, the cold charge velocity changes how the choke needs to behave. A short-ram intake or a square-bore plenum manifold will respond very differently to the same choke setting. This is why some builds with the 650 manual choke seem to work flawlessly while others struggle. It's not the carb that's wrong — it's the mismatch between the choke tuning and the airflow characteristics of your particular intake setup. In my experience, a 350 cubic inch small-block on a standard intake manifold with the manual choke takes about twelve to fifteen seconds of warmup idle before you can safely open the plate. A 383 on a performance manifold might need only eight. Run the engine until the temperature gauge begins to move, then open the choke. That's the most reliable indicator you'll get without pulling apart the setup to measure manifold vacuum.

When the Manual Choke Is the Wrong Choice

There are situations where the manual choke simply won't work well for your application. If you're building a street car that sees daily driving in varying temperatures — especially if you live somewhere that swings from freezing to seventy degrees within a week — the manual choke becomes a chore. You'll be pulling the cable every cold start, and if you forget or get it wrong, the car runs poorly. An electric choke upgrade on the same carb costs roughly forty dollars for a kit and eliminates that variable entirely. The electric choke self-adjusts based on engine temperature. It's not perfect, but it's significantly less fussy than wrestling with a manual cable in subzero weather. Similarly, if you're running a high-duration cam with significant overlap, the engine needs more deliberate choke management than a mild cam does. A rough idle at idle speed combined with a manual choke can make cold driving nearly unbearable. In those cases, consider the electric choke or look at a newer carb like the Edelbrock Performer RPM series which comes with an electric choke from the factory and has improved venturi design for better airflow at low RPM. The Edelbrock 650 Manual Choke carburetor is a solid choice for classic car builds where simplicity is valued and the driving conditions are predictable. It's tunable, repairable, and doesn't require electrical connections beyond what's already in your engine bay. But it demands that you pay attention to cable adjustment, choke plate condition, and warmup procedure. Neglect any of those and you're fighting the carb instead of driving the car.