Hi, I have a 283 in my 1963 impala 4 door pillerless, it floats around at about 210-220 and then starts missing etc low in the rev range, it is running anit rich as it blows a little black out the exhaust when warm. I have put new head gaskets, new carbie, new leads, flushed the radiator and have a 7 blade fan off a ford zd fairlane. Its worth mentioning it is bored out to 40 thou due to it being rebuilt a few times. It has a 2 speed powerglide so would a transcooler drop the temps abit? Or any other ideas? Also whats causing the miss down low when warm? Thank you for any help
I would try advancing the distributor first and see if that doesn't help. On my automatic cars. once everything else has been checked, I set the carb needle valves and idle with the car in gear, brake on or someone pushing on the brakes, until it idles well and at the rpm I desire.
Is the coolant flowing properly? What condition is the rad and water pump in? thermostat working? Is ignition in good condition and set properly? Do you have a fan shroud? Etc. Many questions, many possible causes.
Check coolant for combustion g***es ( test strips) , pressure check cooling system , look to " milk shake" in oil , leakdown & compression checks . Would it be too much to ask to spell out carburetor , it only takes two seconds & doesn't read like a children's book . The other is distributor as opposed to balance/ equilibrium issues .
My son had a similar situation. It ended up being too much fuel pressure pushing fuel past the needle valve (Rochester 4GC). We picked up a replacement fuel pump that fit everything SBC. The pressure was too much for the old 283 carburetor. A good pressure regulator fixed it, and then we had to "dial" it in for most driving situations so it wouldn't starve under load or have too much pressure/fuel at idle. Later I did find an old rebuilt 283 fuel pump from the 1960s which ran a lower pressure. Also, with a 50/50 antifreeze coolant mix and a 7lb radiator cap I think the boiling point is a little over 230 degrees F.
Welcome to the HAMB. You will find that around here you will get better (and faster) results if you post photos of whatever you are having issues with. Fan shrouds work great but the position of the fan blade/shroud opening can have an effect on cooling. As an example, this one is not ideal, should be deeper within the shroud, though this particular shroud does not look very effective, a bit short.
Does it have a fan shroud? What thermostat is in it? What pulleys, are they underdrive? Are you sure you have the correct rotation water pump/fan? Does it have AC and is the condenser or radiator clogged up or fins bent over? Is the trans routed thru the radiator or is it air-cooled?
What is the ignition timing? Any other discussion is worthless until we know. If you set it at 4 to 6 deg with vac hooked up you're running around with pretty retarded timing, which is late firing, which doesn't allow fuel to cool the combustion process, which overheats the headers or exhaust manifolds, which keeps the coolant hot. If you're running with no thermostat you're not allowing the coolant to do its job also, but til then what is the ignition timing?
What is a "zd fairlane"? The shrouds on those were like a drainage culvert, a must to have if you want it to run cool.
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