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#78653 06/09/2007 11:36 PM | Joined: Apr 2002 Posts: 99 Wrench Fetcher | | Wrench Fetcher Joined: Apr 2002 Posts: 99 | I know this site is focused more on older engines than my problem with a 1962 327, 300 HP engines. That being said, I don't think my problem is unique to 1962's.
Engine:
Chevy: 327 cu. in., 300 HP, 4 barrel carb
Problem:
Slight miss when "crusing between 30 and 40 mph.
When I turn off ignition, the engine continues to run, morel like a sputtering and eventually stops.
I use regular, unleaded fuel. I don't know if valve seats have been changed for no-lead gas.
Engine starts and runs fine except for slight miss and sputtering when turned off.
Any help would be greatly appreciated.
Regards,
JD John. | | |
#78654 06/10/2007 1:54 AM | Joined: Feb 2004 Posts: 29,792 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,792 | Regular unleaded- - - - -WRONG CHOICE! If it's actually a 300 HP engine, it has a 10.5:1 compression ratio, and 93 octane will just barely work in it. Regular or mid-grade gas will detonate, and probably cause major engine damage, especially if you do any full-throttle running.
The after-run is probably caused by too high an idle speed. If the car has an automatic transmission, try leaving it in drive as you shut the ignition off. If it's got a stick shift, leave the car in gear and let the clutch out as you shut down. Dropping the idle speed to about 700 RPM or less is the best fix for after-run.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
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#78655 06/10/2007 2:12 AM | Joined: Jul 2004 Posts: 5,708 'Bolter | | 'Bolter Joined: Jul 2004 Posts: 5,708 | JD Bob,
If the idle speed is too high as Jerry mentions, there usually needs to be some source of auto-ignition to light the fuel off after you kill the switch to cause the engine to keep running. Carbon can do this but so can a burned valve or a worn electrode on a plug. One of these items might tie in with your slight miss a mid speed.
A good tune up with a compression test thrown in might help with the diagnosis and could solve the problem.
I don't know if this engine is in your '58 or not. Some alternator installations on rigs that originally had generators will tap off the coil for field power. If not done properly, this can back-feed voltage from the alternator to the coil and cause run-on...this is just a thought.
Stuart | | |
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