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Old 02-25-2005, 09:40 PM
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Motor is misfiring help?

Ok here is my problem my car has had a miss since the day i bought it. When it idles u can here it cut out it sounds like it is only one cylinder because it has a pause between cutting out. It also above 5,000 really starts to cutout and struggles to get up in rpms it gets poppity. I have ran 3 different top ends on this motor. First was the factory TPI. Second was a stealth ram setup. Third it is now carbed. Had 3 sets of wires 3 coils and 2 distributors. The motor is a 92 chevy truck 350 the guy before me rebuilt and i bought it with 2,000 miles on the motor. The guy put a small cam in it, XE262HR other than that the bottom of the motor was rebuilt to stock specs. Does anyone have any ideas as to what might be wrong?

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Old 02-25-2005, 11:50 PM
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Are you sure the cam is not flat?
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Old 02-26-2005, 05:31 AM
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Agree, sounds like a typical flat chevy cam. Could be a broken intake valve spring. Have you put a vacuum guage on it? Do so and note the readings A bad valve or valve spring with show as a sharp quick dip on the guage for every engine revolution.
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Old 02-26-2005, 07:03 AM
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A broken intake spring wont make it miss. It will make it pop through the carb. A broken exhaust spring will make it miss. I had 3 broken springs 2 exhaust and 1 intake so thats where I got my info. Pull all the plug wires 1 at a time with it running. Watch a tach and see the difference. Is it just 1 cylinder? Does it move around? I would do a compression test. See if thats ok. If it has good compression and it comes down to 1 cylinder then you could have a broken spring, a bad cam lobe. or not getting fuel to that cylinder. The last one is not likely if your using a carb. If you suspect a spring try pushing the valve open by hand while its not running. On my motor the only ones I could move were the ones with broken springs.
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