-
Trouble idling when cold
hey,
I have a 350 newly board engine with 9.5/1 comp. New Vortec Heads. Mild cam, about a 440 lift, performer manifold, and 725 road demon carb. The thing runs ok when it warms up, but i have been have weird problems with it when i cools off. When i start the engine in the mourning, it has trouble idling, it jumps around rpms alot and tries to die. Lately, i have had to sit in it to warm it up and keep pumping to gas when its about to die to keep it running. For the first 5 miles or so it runs really bad at low rpm, either with de-accelerating or idleing. It acts like a major vacumm leak. When de-accelerating i have to constantly pump the gas and power break it to keep it running. Im pretty sure i have to choke perectly tuned, and i sprayed ether to try to find a vacumm leak, but no luck. Now im leaning towards a intake manifold leak, or that i need to jet it up a little. It backfires sometimes, and always threw the carb, which means its running lean. My guess is that there is a vacumm leak, and its sucking more air then gas, but i don't understand why when i warms up it runs better. I can drive it until it gets completely up to temp, then park it for 30 minutes, jump back in it while it should still be warm, and it acts up a little until i drive it again. Im know im gonna have to tear into it and find the problem, but does anyone have and suggestions or relations to this problem?
Thanks, Bob B.
-
Most likely problem is the vortec heads...
Those do not have the exhaust ports in em that feed the bottom of the intake.
without a little heat to vaporize the fuel on the bottom of the intake. she's gonna stumble till the engine builds nuff heat to do it. For a good cold run with a carb ya gotta have those heat passages, on an elect. injected car ya dont as the puter can adjust for it.
-
I agree that the Vortec heads not having the heat passages doesn't help the problem, but before i had the demon carb on it, i had a edelbrock carb and manifold and i didn't have this problem. ]: