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Re: Hi RPM misfire
the long and short of it is, you will have to figure out if this is spark related, fuel related, or mechanical.
A timing light, locked timing and a free rev to 5000RPM should show you if the timing is scattering at that RPM or dropping out altogether.
If this were a lean issue, I'd expect intake popping and general nastiness but from your description, it doesn't sound like that. If it were too rich of a mixture, you'd be getting a ton of black smoke out the exhaust right before and during the misfiring.
My money is on ignition still. Make sure you have a good engine ground, and a good chassis ground to battery. Also, cap, rotor, wires (the coil wire wears out faster than the plug wires) all good things to try.
-scott
the long and short of it is, you will have to figure out if this is spark related, fuel related, or mechanical.
A timing light, locked timing and a free rev to 5000RPM should show you if the timing is scattering at that RPM or dropping out altogether.
If this were a lean issue, I'd expect intake popping and general nastiness but from your description, it doesn't sound like that. If it were too rich of a mixture, you'd be getting a ton of black smoke out the exhaust right before and during the misfiring.
My money is on ignition still. Make sure you have a good engine ground, and a good chassis ground to battery. Also, cap, rotor, wires (the coil wire wears out faster than the plug wires) all good things to try.
-scott
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