Timing marks: do they equal one degree or two?
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Junior User
Joined: Mar 2013
Posts: 51
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From: Decatur, Georgia, US of A
Timing marks: do they equal one degree or two?
Also, factory specs are 10-12 deg BTDC on my 400. BUT mine is heavily modified, and heavily cammed....is 15 degrees too far advanced?
Any opinions appreciated!
Any opinions appreciated!
Post Fiend
Joined: Apr 2008
Posts: 8,261
Likes: 15
From: Big Sky Country
15 degrees isn't too much initial advance (IF, you're running ported vacuum and not manifold vacuum), in fact, 15 degrees is probably not enough advance for your particular motor, just be sure that whatever advance you add on the front end (initial) you subtract an equal amount on the back end (mechanical), you don't want to exceed 36-38 total.
On a hi-po motor you want as much initial advance as you can get on the crank and the least amount from the mechanical advance in the distributor, e.g. 18-24 degrees initial timing on the crank and 12-20 degrees of mechanical advance in the distributor to obtain your total of 36-38 degrees of total timing.
You need advance at low rpm to make the engine pull hard, it'll have much better throttle response, a better idle vacuum signal, and it'll run cooler & cleaner.
(the timing marks equal 2 degrees btw)
On a hi-po motor you want as much initial advance as you can get on the crank and the least amount from the mechanical advance in the distributor, e.g. 18-24 degrees initial timing on the crank and 12-20 degrees of mechanical advance in the distributor to obtain your total of 36-38 degrees of total timing.
You need advance at low rpm to make the engine pull hard, it'll have much better throttle response, a better idle vacuum signal, and it'll run cooler & cleaner.
(the timing marks equal 2 degrees btw)
Thread Starter
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Junior User
Joined: Mar 2013
Posts: 51
Likes: 1
From: Decatur, Georgia, US of A
15 degrees isn't too much initial advance (IF, you're running ported vacuum and not manifold vacuum), in fact, 15 degrees is probably not enough advance for your particular motor, just be sure that whatever advance you add on the front end (initial) you subtract an equal amount on the back end (mechanical), you don't want to exceed 36-38 total.
On a hi-po motor you want as much initial advance as you can get on the crank and the least amount from the mechanical advance in the distributor, e.g. 18-24 degrees initial timing on the crank and 12-20 degrees of mechanical advance in the distributor to obtain your total of 36-38 degrees of total timing.
You need advance at low rpm to make the engine pull hard, it'll have much better throttle response, a better idle vacuum signal, and it'll run cooler & cleaner.
(the timing marks equal 2 degrees btw)
On a hi-po motor you want as much initial advance as you can get on the crank and the least amount from the mechanical advance in the distributor, e.g. 18-24 degrees initial timing on the crank and 12-20 degrees of mechanical advance in the distributor to obtain your total of 36-38 degrees of total timing.
You need advance at low rpm to make the engine pull hard, it'll have much better throttle response, a better idle vacuum signal, and it'll run cooler & cleaner.
(the timing marks equal 2 degrees btw)
Senior User
Joined: Mar 2006
Posts: 212
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From: Morganton, NC
Each mark is 2 degrees. Run as much initial advance as you can. I have a 94 Cobra with aluminum heads that can handle 18* before detonation occurs.
I dont think I have ever had a iron headed engine that would take more than 14* without detonation at low RPM cruising.
I dont think I have ever had a iron headed engine that would take more than 14* without detonation at low RPM cruising.
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Junior User
Joined: Mar 2013
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From: Decatur, Georgia, US of A
I just took it to about 17-18 and took it around the block. Highboy, you're right, the throttle response was better and crisper. No pinging. Idle set at about 600 and it seems to like that.
Post Fiend
Joined: Apr 2008
Posts: 8,261
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From: Big Sky Country
Your motor will usually let you know when you've advanced the timing too far, the starter will struggle to turn the engine over, especially when hot, if you reach this point you've gone too far, back off a few degrees.
Just remember, when you add more initial advance on the crank you need to limit the mechanical advance in the distributor an equal amount, otherwise, the motor will start to ping well before the mechanical advance is "all in" around 3,000 rpms.
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Junior User
Joined: Mar 2013
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From: Decatur, Georgia, US of A
You can run as much initial advance as the motor will tolerate (up to a certain point) just be sure to listen for detonation (pinging), if you hear it, back off in 2 degree increments until it goes away.
Your motor will usually let you know when you've advanced the timing too far, the starter will struggle to turn the engine over, especially when hot, if you reach this point you've gone too far, back off a few degrees.
Just remember, when you add more initial advance on the crank you need to limit the mechanical advance in the distributor an equal amount, otherwise, the motor will start to ping well before the mechanical advance is "all in" around 3,000 rpms.
Your motor will usually let you know when you've advanced the timing too far, the starter will struggle to turn the engine over, especially when hot, if you reach this point you've gone too far, back off a few degrees.
Just remember, when you add more initial advance on the crank you need to limit the mechanical advance in the distributor an equal amount, otherwise, the motor will start to ping well before the mechanical advance is "all in" around 3,000 rpms.
Could this be related to the timing??? It feels like what the ignition coil did when it failed, but of course I have a brand new one on there now and it's just fine.
Distributor itself is cheap junk from Autozone.
Flummoxed.
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Junior User
Joined: Mar 2013
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From: Decatur, Georgia, US of A
AND I should add...when I was really stepping on it, it was hauling...no pinging at all. Very strong. But, like I said, then it just started missing real bad and engine died.
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