I'm a newbie and haven't contributed much yet, but I really hope that someday I could help someone in this kind of situation. I'm having bad troubles with my '50 Chevy. I can't figure out the exact reason it does what it does. Tried to search, but didn't find a thread that could help me out. I decided to ask help to see if someone would come up with the educated guess after hearing the symptoms. That would be great, since I had to leave the car to my parents (a 100 miles away) after it died, and I'd rather gather the right tools/parts beforehand and drive it home instead of towing... The car came to me last January. It has a '53 235 six from a non-PG car. Engine appears to be stock, but I swapped the intake/exhaust as a unit from a newer 261, because the original exhaust was split, and the extra outlet broke off. I kept the original single barrel rochester carb. I converted the car to 12 volt system w/ a new generator, new battery and a used 12-volt coil. I changed the oil and the plugs. I first drove shorter distances, and it ran like a champ. On the first longer trip it died after about 45 minutes of driving. It started to stall and pull just like if it was out of gas. I fetched some gas but it didn't help. I managed to drive short pulls at a time. Then I waited for help, and after an attempt to tow with a rope (it snapped pretty soon), I managed to drive home, a drive that took about 15-20 minutes. I didn't have much time to tinker with it before I needed it in my wedding that was taking place almost 200 miles away. I thought maybe it just had too little gas, and dirt in the fuel system, so I flushed a lot of gas out from the bottom of the tank and cleaned the bowl and the screen at the fuel pump. I filled it up and checked that fuel was flowing freely to the carb while cranking. I then tested it by driving it to work and back, which takes almost 30 mins to one direction. It ran strongly and I crossed my fingers and packed my tools for the long trip. Well, of course it died, after running strongly for about 45 minutes. After that it ran only short distances, after cooling down a little. I filled it up a couple of times during the trip. My mum and dad came to rescue and towed me with a rope the last 50 miles. The trip took me at least 7 hours. Man, I was happy... The actual good thing was that it didn't let us down during the short trip required to drive in our wedding. I was there for a week beforehand, but didn't have any time to work with it, since there was so many other preparations to make for the wedding. After the wedding I was there for almost a week clearing things off after the wedding, and again, I didn't have much time to work with it. I was almost sure that it had been vapor locking. I tossed in an electrical pump and rerouted the line around the mechanical pump. The same time I noticed that attachment of the fuel line at the tank was kinked a bit and leaked a bit, because the line had been hit by the axle. I fixed this and checked that fuel was flowing freely from the tank. I surely hoped that it would work now, and me and my newly-wed wife headed home. Of course it didn't work. Steady cruising and part throttle were OK, but from the beginning it worked worse than earlier at open throttle. It ran about half an hour and died. My wife was driving our Caprice and we had with us the good rope with which my dad had towed me earlier. We decided to tow it to my parents' house, because it was half the distance and much flatter ground. Now my vacation is over and we have to go get it home the next weekend, and after all this towing, I surely would love to drive it home.. Now it runs all the way worse than earlier. It starts, but the more I step on the throttle, the ****tier it runs. If I pump the throttle enough, it dies completely. I tried a different coil (the original 6-volt), no difference. I lifted off the top of the carb to see fuel level. It was about a fingerwidth below the mating surface of the bowl and the top. I swapped in the carb from the newer 261. It idled better, but again started to run worse when giving it the throttle and eventually died when pumping the gas pedal. It had the same fuel level as the original carb. Some other things... Condenser and the points at least look good. It hasn't lost oil, and the oil looks good and doesn't smell much like gasoline. Again I didn't have enough time with the car, and for some reason didn't check the spark plugs, but I can ask my dad to check that for me if it would help. It hasn't smoked at any point, and when it idles, the exhaust smells normal. Distributor advance turns freely by hand. Exhaust heating system moves freely.
First thing I'd try is a new coil and condenser. It can be typical of both of them to quit working when they get hot, and resume working after cooling off. Good luck ..... EDIT: Whoops! Just reread your post and saw you'd tried a "different" coil. I'm ***uming another used one? I'd still replace it with a new one .... they're cheap enough. (Or used to be!) Condenser could still be the villain.
You need to narrow down your problem a little more. The next time you have time to work on the Chevy (I understand the pressures of being a newly wed but trust me it will too soon p***) take a friend with you, before you go remove the aircleaner. Drive normally and wait for the car to do its evil thing. As soon as it stalls jump out and check down the throat of the carb while your companion (perhaps your new bride?) pumps the gas pedal, if you see gas from the accelerator pump gas is probably not the problem. Go to the other side of the motor pull the coil wire from the distributor and while holding it near bare metal have your helper spin the car over with the ignition on, look and listen for a big fat spark. If it's got spark thats probably not your problem either. It will be one or the other I'm sure, now just wait around for it to cool down and restart (another good reason to bring the new bride nudge nudge wink wink). The ignition switch in old Chevys can get tired as well, take a jumper wire and go from the battery directly to the poitive side of the coil and try starting with the switch off ***uming you are still running the push ****on, if it fires up the switch could be faulty.
I came across this; 6 volt to 12 Volt conversion General Applications FAQ on Converting. One of the most frequently ask questions we get are, "How do I upgrade to 12 volts". The 12 volt upgrade is probably the ... sanjosechevys.org/Tech/tech_6-12_Volt_​Conv.htm - Cached You will need to add a ceramic ballast resister to your 6 volt ignition coil. A firewall mounted resistor, such as thoughts use on early 12 volt GM products are the easiest. These resistors are available from Napa Auto Parts for about $10.00.( Napa Part Echlin ICR-13) The resistor is installed inline on the 12 volts supply to the distributor dropping the ignition to 6 volts. (***I know you said you put a 12 volt coil on - but maybe try taking it off ****)
Thanks, all! I was leaning towards it being an ignition problem, after trying two carbs and seeing they both had gas in the bowl after it stalled... must check the accelerator pump though. I think I'll check the accelerator pump shot, then the spark. If the spark is weak I see what a jumper wire, coil, or condenser does, one of the time... If I still can't find the problem and don't get it running, we'll just tow the ******* home (so agonizing as it is) and I'll continue narrowing the problem from there.
have you been to the stoveboltforum? there are many people there that know these engines in-and-out. if you haven't, do an intro then post your question there on the tech forum. may help -DVZ
Do you have the stock spacer/insulator between the carb and intake? It's meant to prevent vapor lock. ...just a thought.
Yes, the cap seems to be breathing, since it didn't hiss or pop when opening after stalling on the road. Also there is an insulator under the carb.
Found a pic about the correct fuel level when the air horn is removed: Another shot of the inside of the bowl: Not sure, but I think the level was higher on the both carbs. It made me wonder... Perhaps it was vaporlocking or starving before because of the kink/leak at the tank, and is drowning now as the kink is fixed and the electrical pump added... But in that case, shouldn't it work better when @ open throttle or when pumping the pedal (just the opposite to how it has acted on the electrical pump)?? Shouldn't it also smoke when running?
We went there on saturday. This time it didn't even give a slightest promise to fire up . The coil gave a spark, but I tested it with another just to make sure, and it gave a little better spark. Also checked that an individual plug wire gave spark, and that a plug seemed to be ok. Also swapped the condenser just in case. The fuel level was a little high with the electric pump, so I tried to start it for some time without running a pump at all, and then with the original mechanical pump. The accelerator pump of the carb worked. As far as I know, if there are both fuel and spark present, it should at least try to fire at some point...but it just didn't. It was time to give up and have some beer... On sunday we towed it the hundred miles home. It actually went really smoothly, and on the best stretches we could tow at 50 mph. I'm still happy to own a 1950 Chevy, although it actually isn't as "automobile" right now as it was designed to be... Well, I just have to start with the basics now and check and fix one thing after another. After all, I was going to swap the whole engine before the next summer anyway.
Hmm. Usually stumbling under load indicates it's not getting enough fuel, like the filter is clogged or the pump is failing. Presumably you've checked what the actual pressure is at the carb at this point? But it doesn't have to be much, 4-6 psi I believe is plenty. The next thing I would look at is to make sure the vaccuum lines for the advance on the distributor are in good shape with no leaks. Not enough advance because of a leak could be a reason for the breaking up at higher RPMs. It also could vary when it will do it - rubber is a funny thing, it might not leak cold but once hot and it expands a crack could turn into a leak. For that matter, check the plug wires out too - I had a set do exactly that, the truck would run great cold, when hot it would misfire, the boots were shorting out on the manifolds through small cracks and I couldn't hear it over the exhaust nor see it because it was a Chevy V8 and the boots are right in next to the exhaust manifold on them, it gave me fits for a month or so. If you're priming the carb with gas, you have a spark, and it still doesn't run, check where the timing is set. Perhaps it's jumped time somehow. I seem to remember the original timing gears on these motors are prone to failure because they're made of some kind of material to reduce noise. But even with steel gears sometimes a worn chain can jump a tooth or two. Sooner or later with everything set right, it has to run. You might look into tracking down a Carter YF carb, though, they're much better than that leaky old Rochester B that's on it now.
I don't know if you already checked this, but to me it almost seem like your problem could be a leaky fuelline!?! I had the problem with my '53-It was the same idle fine and the more I went on it the worse the engine would run! I found that I had a small hole in the rubber fuelline and the more I stepped on the gas pedal the more air it would **** through the damn hole.... I tell you the damn hole was so little that it was barely noticeable when inspecting the line! Hope you'll solve your problem. Klaus
I too think this is a fuel carb issue ... are the carbs your using rebuilt or fairly fresh..? I would stick with one carb and rebuild it . does it idle right ?
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