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Author
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Topic: timing
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6shooter
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Member # 1246
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posted
 
 
can anyone explain total timing and what a timing adjuster on a 4.6 effects it(example:if there is a chip installed and the tuner says 16' timing; if you then advance it with the timing adjuster to say, 15', how is the total timing effected).Another example; stock timing on a 96 cobra is 10'. if you set the timing adjuster to 15', what is really happening?
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Paxton Novi 2000,FMS Shorties,Bassani X w/cats,FMS Oval TB,JMS Chip,42lb inj.,255gph intank pump, Pro-M 87mm, saleen wheels, Tremec 6-speed, 4.10gears
Posts: 11 | From: St. Louis | Registered: May 2002
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Gear Head
JARED
Member # 779
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posted
By increasing the timing you are speeding up the motor. Basically making it crank faster to get more power and run more efficent.
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Posts: 5685 | From: EASTBAY | Registered: Jan 2002
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Stimson
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Member # 51
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quote:
Originally posted by sic91sleeper:
By increasing the timing you are speeding up the motor. Basically making it crank faster to get more power and run more efficent.
This is completely incorrect in every way.
Posts: 2373 | Registered: Jun 2000
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6shooter
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Member # 1246
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posted
anybody else? when the chip tuner says 16' timing, is this total or advanced? the reason i ask is this. i ordered a chip. the paper says it's programmed for 16' timing. i have a blower making 10lbs boost. the car is losing power 100% at 6200rpm at .035 spark plug gap. at .025 gap no problem too 7000rpm, but power is down at low rpms. i put the gap back at .035 and with timing adjuster moved to the 12 mark(10 being stock), the car seems to be reacting better. now it is knocking off at about 6800rpm. can i keep advancing the adjuster, or will the timing be bad enough to hurt the car. at 12'advance with adjuster, there is no pinging yet. ![[Confused]](confused.gif)
Posts: 11 | From: St. Louis | Registered: May 2002
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Gear Head
JARED
Member # 779
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posted
quote:
Originally posted by st5150:
quote:
Originally posted by sic91sleeper:
By increasing the timing you are speeding up the motor. Basically making it crank faster to get more power and run more efficent.
This is completely incorrect in every way.
then enlighten us sti515 or w/e
[ May 08, 2002, 09:01 PM: Message edited by: sic91sleeper ]
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Support our troops!
Posts: 5685 | From: EASTBAY | Registered: Jan 2002
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Stimson
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Member # 51
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posted
quote:
Originally posted by 6shooter:
can anyone explain total timing and what a timing adjuster on a 4.6 effects it(example:if there is a chip installed and the tuner says 16' timing; if you then advance it with the timing adjuster to say, 15', how is the total timing effected).Another example; stock timing on a 96 cobra is 10'. if you set the timing adjuster to 15', what is really happening?
I'll give a crack at it, even though its more typing than I'm willing to do right now. "total advance" is how many degrees of crank rotation before the #1 piston reaches top dead center. The spark plug fires before the piston reaches its peak "hight" in the cylinder because the air/gas mixure is a relatively slow burn. If you have it ignite too soon, the flame will be going down while the piston is moving up (detonation), if you have it fire too late, the flame will push the piston down as the piston is already moving down (power left on the table). The timing adjuster lets you tweak the timing and find the sweet spot between detonation and power left on the table.
Posts: 2373 | Registered: Jun 2000
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6shooter
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Member # 1246
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posted
the chip tuner is one of the more popular tuners is the US, rather not say to protect their name. do you think the term 16'timing on my spec sheet is the total timing, or 16'advanced?
Posts: 11 | From: St. Louis | Registered: May 2002
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ScuEleanor
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Member # 785
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posted
When the piston is in the compression stroke, both valves must be closed. If one or more is open, the valve timing is out. Perhaps a timing belt or timing chain has jumped a tooth. If the spark does not arrive at the correct moment, the engine is out of time. If this ignition timing is only slightly off, the engine may run with less efficiency = Timing.
It causes the valves to open and close at the proper time =Timing Belt
A drive chain driven by the crankshaft and operates the camshaft. It causes the valves to open and close at the proper time. = Timing Chain
Hope this helps
Posts: 77 | From: Santa Clara | Registered: Jan 2002
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ScuEleanor
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Member # 785
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Advancing the timing changing the ignition timing so that the spark occurs earlier in the cycle. The opposite is retard.
Posts: 77 | From: Santa Clara | Registered: Jan 2002
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1SLOWLX
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Member # 558
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Well with my chip tunner he told me to set the timing at stock 10. He advanced mine by the computer and shit
Albert
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Built Tuff with your stuff ;)
Posts: 5231 | From: bay area | Registered: Nov 2001
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Stimson
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Member # 51
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posted
quote:
Originally posted by 6shooter:
if you set the timing adjuster to 15', what is really happening?
Okay, to answer your question more directly, the computer (EEC) doesn't measure advance. It asumes a "Base" value and advances timing acordingly. For example, on a typical 5.O, the EEC assumes the distributor is set at 10 degrees initial, and the EEC advances the timing as much as 26 degrees under full load for a "total" timing of 36 degrees. I'm not sure how much the 4.6's advance timing, but it should be about the same. If you use the timing adjuser to change the base timing to 15 degrees from the factory ten, the EEC will add 26 degrees on top of that for a total of 41 degrees total advance.
*Keep in mind this whole time that timing is when the spark plug is fired (measured in degrees of crank rotation) before the piston reaches its peak travel. To rephrase it, When you adjust the timing, you're adjusting the "time" the spark plug fires relative to the piston's postition, and its units of measurement isn't seconds, but rather degrees (of crank rotation). I hope this makes sense. Its hard to explain with out pictures and diagrams.
Posts: 2373 | Registered: Jun 2000
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ScuEleanor
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Member # 785
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posted
Typically the piston is already on its way down from the compression stroke before the spark plug ignites the air/fuel mixture. A few degrees is all it takes to regain lost power and deliver it to the crankshaft. A crank sensor determines the proper timing of the coil-packs, which fire the spark. The timing adjuster allows you to relocate the crank sensor and adjust its relative orientation to the crank to improve spark timing. For a Supercharged Cobra, start with 9 and then subtract 1° for every 2 psi of boost (example for 8 psi: 9°-4=5°)
P.S. I am hoping you know that your car doesn't have a distributor, hence the crank sensor.
Posts: 77 | From: Santa Clara | Registered: Jan 2002
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ScuEleanor
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Member # 785
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Also if you are looking to buy an adjuster, the Steeda 4.6 Adjuster will do fine. It has a clear notch mark stating the 10 degree stock location and then has availability to advance and retard 10 degrees.
Posts: 77 | From: Santa Clara | Registered: Jan 2002
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