(1972 302 stock 2100 carb) okay, got a hot start problem and not sure where to start. Say you drive some where, like a store, turn it off and go shop say less than 30 minutes, usally to get it started you wind up having to hold it to the floor, crank say 5 seconds or so(never counted) It will catch ease off an hold a fast idle for a second then let it idle. I have tried different choke combos and nothin seems to help. I feel like it is flooding out a little bit, and wont start with out some pedal, then it floods worse when you open the throttle. some times after i park it, i can smell gas at the front of the car, but never see any.. And sometimes it is even harder to start. Where should i start lookin? What would cause it to lose some gas after a hot shutdown, but take a few minutes? What does the power valve do? What symptons do you have if it is going bad? i feel the needle is holding, maybe the level is a little high?? so where should i start checkin? And anybody tell me about the power valve functuion? And its symptoms when it starts to go bad?? later!! And sorry for writing a book.. chris
Have you tried it without using the choke at all? Just start cranking the engine and as it cranks just press down slowly on the gas pedal.
This could be your problem. The power valve is for fuel enrichment in a low vacuum condition. It should be closed at idle. It is common for them to leak and thus cause hard starting and an over-rich condition. To check it, remove the carb. The power valve is located under a small square cover located under the float bowl. While keeping the carb oriented upright, remove the 4 cover retaining screws. If it is wet inside the cover, the power valve is leaking. Simply unscrew it to replace.
Your bowl is empty. The PV or accellerator pump is leaking all your fuel out when the car sits. You have to crank so long to fill the bowl back up before the car starts. That is where the gas smell is coming from... The leak. These leaks could be internal, so you may not see fuel. It can even build up under the carb mounting pad and burn off there. Fix the leak, or better yet rebuild the carb. Dave
I should have elaborated more on the power valve leak. If it is a bad leak, it will drain the bowl, but what causes the flooding is that even with a small leak, the fuel is drawn through the vacuum passage on the opposite side of the power valve.
okay went and braved the cold tonight and pulled the carb. I took off the air horn and gasket, turned it up side down took off power valve cover, it was wet so i removed the valve and gasket. I noticed there was some gunk in the bottom of the carb so i pulled the float and needle. Took some carb cleaner and cleaned the bowl real good and shot some through the main jets. Also opened the butterflies and cleaned down in there. Then followed up with the aire hose and blew every thing out. Put hte new power valve and gasket in and just snugged it, and then the cover with new gasket. Turned it back over and put the old needle and float back in, with new air horn gasket then put the air horn back on. The carb stayed stuck to the spacer and the spacer came loose from the intake. The old gasket looked pretty good and was stuck solid. So instead of scraping for an hour in the cold and wind i just reused it. Mounted it back up rehooked every thing primed the bowl with some gas down the vent, pumped up the accelerator pump, double checked every thing, hoped in set the choke and cranked her off. Ran atleast as good as before so that was a good start. Mounted the air cleaner let her warm up and took her for a spin. She ran good and maybe a little more power, and smoothness. It also seems to idle smoother. I smell no gas now, and restarted easily after sitting hot for like ten minutes. So right now it looks like a definative improvement. But i have two new questions. The idle jets are set out just over two and a half turns, does this sound about right? I havent fooled with tuning them any more yet.. And secondly as you come up off idle and get to a faster idle it runs kinda rough, not a smooth purr, but if you keep on going it tends to smooth out, i am guessing the roughness is coming from the idle side and is smoothing out once you hit the high side. so any ideas on what to look at for that??? later!! and sorry about writing a book again!! chris
The transfer from the idle circuit to the cruise circuit has always been a problem area. Too rich or too lean an idle mixture or too high or low an idle can contribute to the problem. There is a cheat that can cover up a lot of mis-tuning - the accelerator pump. When you have a problem the easy fix is to tune the accelerator pump to cover up the problem. The right way to fix the problem is to tune your idle speed and mixture to minimize any off idle stumble and then use the accelerator pump to work out the rest.
