The Stovebolt Site Forums The Shop Area Engine Shop Trouble with carbuerator when cold

My 65 fleetside would not crank. I did all the regular checks, fuel lines, filter, everything was good. After a few days of confusion, I thought to do like my grandfather did. I poured a little gas in the carb and it fired right up on the first turn of the key instantly. What is the problem, and how can I fix it. Hello to all, this is my first post.

"Cranking" involves the starter making the engine turn over, which it sounds like is happening. A "no start" condition with normal cranking speed involves low compression, lack of fuel, or no spark. Since adding a squirt of fuel makes the engine start, I'm going to assume your compression and spark are adequate, if not perfect. Yod haven't mentioned if you have a manual or an automatic choke. If it's manual, do you know if the choke is closing all the way when you pull the knob? Check on that, as sometimes the choke plate will not move far enough to get enough restriction to the airflow. A choke operates by strangling off airflow at the top of the carburetor, and letting intake manifold vacuum be applied to all the fuel passages in the carb. The temporary very rich mixture allows enough fuel to reach the cylinders that at least some of it burns. Once the engine fires, release the choke slightly to avoid flooding, or over-rich running during warmup. Adjust a manual choke by shortening the cable until the choke plate closes all the way just as the knob on the dash reaches the end of its travel.

If you've got an automatic choke that's working right, it should do all the cold-start things for you- - - - -just tap the gas once and crank the engine. The choke plate should snap closed, and once the engine starts, it will release itself slightly. As long as the choke is partially applied, a "fast idle" system will keep the engine from stalling. Automatic chokes get sticky and don't close all the way, so soak the choke linkage down with lots of spray carb cleaner and work it back and forth until all the parts move freely. The choke coil should make the valve close when the engine is cold, at least enough to restrict the airflow on the first start-up. Adjust it by loosening the hold-down screws on the choke cover, and rotate it to increase the spring tension on the choke plate.
Jerry

Also take a look at the acellerator pump action. With the engine off. look down the throat of the carb & work the throttle open & shut. Each time a squirt of gas should go into the throat. This acts the same as pouring a little gas down it. If it doesn't work you need some carb work. If it does maybe you are not using it enough for a cold engine. These modern cars we have now with fuel injection pumping the throttle has no effect on anything. The old vehicles with carbs. we had to pump it several times on a cold start.

I have no choke at all, forgot to mention, since this problem has just started a couple weeks ago. I've been running it with no choke for about six months. I just sit there and keep the foot pedal depressed and adjust by the sound of it running until it warms up. About that no choke, my old rodchester 2 bl had to be replaced, I put a holley on it that uses a heat riser spring, which I do not have. My regular set-up used a manual choke, which I really liked. Thanks for the informative reply.

Thanks for your input, didn't think about the looking in the carb trick. Went to crank it this afternoon and it fired right up, can't figure it out.

I have been looking for the correct heat riser spring for my new manual choke carb to fit on the manifold of my 65 283. I have tried many and had to return them. As things happen, I was about to switch to a quadrajet manifold and put in a 4 bl., but when I received the quad manifold, quess what, sitting right there on the late 60's 283 quad manifold was the spring that will fit the set up that I have now on my 65 2 bl. manifold. Some things happen that way. By the way, my truck has been cranking on the first try ever since I received your post. I'll run it with the set-up as it is now until I figure out my next move. The detailed explanation was appreciated.