correct ignition adavance
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Cargo Master
Joined: Sep 2007
Posts: 2,095
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From: Wahpeton ND
correct ignition adavance
I just installed a pertronix in my 64 f100 and it works wounderful. However i notice a occasional knock when driving at 65 mph or more. what is the correct abount of advance at idle.
New User
Joined: Oct 2005
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correct ignition adavance
Hopefully this will open a can of worms...I have always been told the stated specs are the ball park figure to run. They do not take into account the altitude, octane/quality of fuel, or the build and condition of the engine. The best way to set the advance is to advance it till it pings and then back off a bit. A ping that is seldom heard is not harmful. Change brands of fuel or even the grade may eliminate the problem. Sounds like you are very close to the desired settings for your use. J
Logistics Pro
Joined: Feb 2005
Posts: 3,952
Likes: 117
From: Upper Left Coast
Howdy,
no worms here......just ants!
You might have some issues with the advance weights and springs in your distributor. It may be advancing your timing more than it should be advanced at high RPM. I cannot remember what the total advance should be but an auto electric shop that does distributor tuning will be able to tell you what it should and put yours on a test setup and tell you what it's doing. It's possible that you have a broken spring etc...
You could also have an engine that's running hot and/or is somewhat carbon'd up and has a hot spot in some of the combustion chambers that is causing preignition.
It's not something you want the engine to do a lot.....especially under load.
Cheers,
Rick
no worms here......just ants!
You might have some issues with the advance weights and springs in your distributor. It may be advancing your timing more than it should be advanced at high RPM. I cannot remember what the total advance should be but an auto electric shop that does distributor tuning will be able to tell you what it should and put yours on a test setup and tell you what it's doing. It's possible that you have a broken spring etc...
You could also have an engine that's running hot and/or is somewhat carbon'd up and has a hot spot in some of the combustion chambers that is causing preignition.
It's not something you want the engine to do a lot.....especially under load.
Cheers,
Rick
Posting Guru
Joined: Jul 2003
Posts: 1,398
Likes: 2
From: Davenport, IA
I was playing with the advances for awhile - and I'd like to get back to it. As of now, I'm running about 10 initial, 35-40 with vaccum, and am somewhere around 10 degrees all-in mechanical advance at 4000rpms. I discovered I had some other issues that were affecting (afflicting) my motor, so I need to start over with the timing.
Laughing Gas
Joined: Oct 2003
Posts: 890
Likes: 0
From: New York
I think factory spec is 2 to 6 BTDC initial, depending on fuel octane rating.
John Mummert, ford-y-block.com, recommends 8-10 BTDC initial for most engines. (Initial timing, of course, doesn't include vacuum- should be measured with vacuum advance disconnected). I'm currently running my stock 292 at 10 BTDC on 93 octane, and it runs great. Vacuum advance hooked to manifold vacuum, and no modifications to the stock advance curve---- just make sure that the vacuum diaphragm and advance weights are working right.
John Mummert, ford-y-block.com, recommends 8-10 BTDC initial for most engines. (Initial timing, of course, doesn't include vacuum- should be measured with vacuum advance disconnected). I'm currently running my stock 292 at 10 BTDC on 93 octane, and it runs great. Vacuum advance hooked to manifold vacuum, and no modifications to the stock advance curve---- just make sure that the vacuum diaphragm and advance weights are working right.
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