Have a timing question
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From: reedsport
Have a timing question
1986 460 motor. P.O. Removed all smog and egr stuff. The valve cover says set timing to 8 btdc. Should it be different now that all egr and vacuum stuff removed? The vacuum advance is still hooked up. Duraspark system. I’m doing everything I can to figure out why the carb is backfiring before I get into valves. Thanks
Post Fiend
Joined: Apr 2002
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From: Waterloo, Iowa
Disconnect and plug vac. advance. Set it to 12° or so and then (careful!) run it up in neutral to 3-4k and see where it tops out at. Probably 34° or 36° ... that's the ballpark. Experiment. Take some test drives, without vac. advance hooked back up yet. Try advancing the distributir a little bit more. Figure out what's installed in the distributor now in terms of advance curve. Write it down. By measuring at 500 RPM, 1000 RPM in neutral etc, you'll soon determine if the distributor adjustment is suitable. A "rebuilt" distributor could have came from a Pinto, or maybe a dump truck, who knows.
Make sure the mechanism advances and moves smoothly with a timing light. Also check that when the vac. advance is hooked back up that the diaphragm holds vacuum. If it doesn't, that can cause backfire. Can play with different weight springs and advance curves. This can really wake up a motor and doesn't cost a lot.
Make sure the mechanism advances and moves smoothly with a timing light. Also check that when the vac. advance is hooked back up that the diaphragm holds vacuum. If it doesn't, that can cause backfire. Can play with different weight springs and advance curves. This can really wake up a motor and doesn't cost a lot.
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More Turbo
Joined: Jun 2010
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From: reedsport
Dusconnect and plug vac. advance. Set it to 12° and then (careful!) run it up in neutral to 3-4k and see where it tops out at. Probably 34° or 36° ... that's the ballpark. Experiment.
Make sure the mechanism advances and moves smoothly. Also check that the vac. advance is hooked back up that the diaphragm holds vacuum. If it doesn't can cause backfire. Can play with different springs and advance curves. This can really wake up a motor and doesn't cost a lot.
Make sure the mechanism advances and moves smoothly. Also check that the vac. advance is hooked back up that the diaphragm holds vacuum. If it doesn't can cause backfire. Can play with different springs and advance curves. This can really wake up a motor and doesn't cost a lot.
Thread Starter
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More Turbo
Joined: Jun 2010
Posts: 546
Likes: 1
From: reedsport
Disconnect and plug vac. advance. Set it to 12° or so and then (careful!) run it up in neutral to 3-4k and see where it tops out at. Probably 34° or 36° ... that's the ballpark. Experiment. Take some test drives, without vac. advance hooked back up yet. Try advancing the distributir a little bit more. Figure out what's installed in the distributor now in terms of advance curve. Write it down. By measuring at 500 RPM, 1000 RPM in neutral etc, you'll soon determine if the distributor adjustment is suitable. A "rebuilt" distributor could have came from a Pinto, or maybe a dump truck, who knows.
Make sure the mechanism advances and moves smoothly with a timing light. Also check that when the vac. advance is hooked back up that the diaphragm holds vacuum. If it doesn't, that can cause backfire. Can play with different weight springs and advance curves. This can really wake up a motor and doesn't cost a lot.
Make sure the mechanism advances and moves smoothly with a timing light. Also check that when the vac. advance is hooked back up that the diaphragm holds vacuum. If it doesn't, that can cause backfire. Can play with different weight springs and advance curves. This can really wake up a motor and doesn't cost a lot.
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From: reedsport
yes. It ran better but pops higher rpm. Not popping off idle
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Lead Driver
Joined: Mar 2004
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So, the engine ran fine till you removed the smog stuff, or was it having problems that lead up to you removing the smog stuff thinking that might fix it ?
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From: reedsport
i bought it like that with everything removed it never ran right.
Lead Driver
Joined: Mar 2004
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Then the first thing I would do is verify the condition of the engine by doing a compression test or leak down test. For all you know at this point, the motor could be shot and your just wasting your time with it.
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