I have a big block 454 , only about 70,000 miles on it. Starts fine and idles fine. I kinda timed it by ear, do not have a timing light. what happens is that it doesnt seem to have the power that it should when I get on it driving. and when I rev it up at idle, it seems to start stumbling at about 3000-3500 rpms and blowing black smoke out the exhaust. Question, is the coil weak or is the timing to retarded or is this question retarded ?
CK5
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running rough at high rpms
- Thread starter scrappyk5
- Start date
Need more info--like is it carbed,or has EFI,have HEI or points,etc....hard to make a guess with such limited info to go on..
Black smoke is usually gas, as you know.
You could have a problem with the choke plate getting pulled down at high speeds if its loose, but most likely its a misfire.
And with that, you just have to go through the usual suspects. Plugs, wires, cap, rotor, coil spring, ignition module.
As always, never assume new is good.
Spraying water on the wires while it is running at night will show up a bad wire either through causing a stumble or seeing an arc.
Otherwise, pull the cap and check for problems, pop the coil out if its in the cap and look for corrosion where it makes contact through that spring.
Lastly, pull the plugs and look for one that has not been firing right.
You could have a problem with the choke plate getting pulled down at high speeds if its loose, but most likely its a misfire.
And with that, you just have to go through the usual suspects. Plugs, wires, cap, rotor, coil spring, ignition module.
As always, never assume new is good.
Spraying water on the wires while it is running at night will show up a bad wire either through causing a stumble or seeing an arc.
Otherwise, pull the cap and check for problems, pop the coil out if its in the cap and look for corrosion where it makes contact through that spring.
Lastly, pull the plugs and look for one that has not been firing right.
