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Checking Total Mechanical Advanced Timing

  • Thread starter Thread starter 93gtmustang
  • Start date Start date Jul 29, 2007

93gtmustang

10 Year Member
Oct 21, 2006
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49
Jul 29, 2007
#1
  • Jul 29, 2007
  • #1
This is from Ford Racing's web site.
Engine Installation and Tuning Tips.
Typical total mechanical advanced timing at 4000rpms for Ford Racing Performance
Parts crate engines: 5.0L : 36 to 38 degrees


My timing is at 15 degrees advanced at idle with timing the spout disconnected.
I tried to check it to see if it was at 36 to 38 degrees at 4000 rpms and it still read 15 degrees. Do I have to do anything different to check total mechanical advanced timing?
I read the below from a link that Bill302 posted, real good information.

Ignition Curving

Here's one we see all the time. Did you know improper ignition tuning not only adversely affects performance, but it also can do permanent engine damage? Here's why: Ignition timing isn't just about aiming a timing light and getting 6 or 12 degrees BTDC timing at idle. What really counts is total timing and how it synchs with engine rpm. Total timing, meaning total spark advance in degrees of crankshaft rotation/position, should be completely in by 3,000 rpm.



As a rule, total timing should never exceed 36 degrees BTDC at 3,000 rpm and higher. Some people push the envelope and crank a few extra degrees in there thinking it will net us more power. But, when you dial in too much timing, you run a high risk of serious engine damage from detonation/spark knock. This happens when fuel ignition occurs too early on compression/ignition stroke.

The objective is to light the mixture at exactly the right time as the piston rises in the cylinder to where combustion is fully underway when the piston reaches top dead center. This hinges on fuel octane rating, ambient temperature, humidity, cam profile, chamber size and shape, air/fuel mixture, and atmospheric pressure (or pressure altitude). Every situation is different, which means no two engines will respond the same way to ignition curve. What works on your buddy's 302 likely will not work on yours.

And remember something else: Total timing when the engine isn't under a load is different than total timing with a load. With a load, you often need less timing because detonation typically occurs heavy load at wide-open throttle at low rpm. This calls for retarding total timing one degree at a time.
 

bill302

Active Member
Nov 2, 2005
2,131
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alabama,gadsden
Jul 29, 2007
#2
  • Jul 29, 2007
  • #2
did you reinsert your spout connector to check total mechanical advanced timing...
 

93gtmustang

10 Year Member
Oct 21, 2006
524
43
49
Jul 29, 2007
#3
  • Jul 29, 2007
  • #3
No I didn't. Does the spout have to be in to check total mechanical advanced timing?
 

bill302

Active Member
Nov 2, 2005
2,131
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46
alabama,gadsden
Jul 30, 2007
#4
  • Jul 30, 2007
  • #4
yes
 

rj95svt

Member
Jan 11, 2007
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0
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Hayden, AL
Jul 30, 2007
#5
  • Jul 30, 2007
  • #5
Isn't checking the total timing advance pointless in a fuel injected engine? I mean if your just sitting there revving the engine while checking the timing with the spout in is the computer going to advance the timing like it would under a load? I figured total timing is something that is checked on carbed cars. To get a true representation of total timing with a fuel injected engine the only way to really know the total timing is if you have a way to datalog WOT timing in the computer isn't it?
Total mechanical advance only applys to engines with mechanical advance in the distributor sucha as springs and weights. Our fuel injected engines advance timing in the computer.
 

93gtmustang

10 Year Member
Oct 21, 2006
524
43
49
Aug 4, 2007
#6
  • Aug 4, 2007
  • #6
I just checked my timing with the spout in at 4000 rpms.
I made two marks. One at 36 and one at 38 degrees advanced.
I estimate it was at about 30 degrees advanced.
I didn't really want to stick my head to far in with motor at 4k!
My timing at idle is at 15 degrees advanced.
If I was to go by the total timing advanced, that would put my idle timing at about 18 degrees advanced.

Is rj95svt correct in saying, "checking total timing advanced is pointless on a efi engine"

Maybe jrichker would have the answer to this.

I'm going to call Ford Racing Monday also.
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
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129
Aug 4, 2007
#7
  • Aug 4, 2007
  • #7
It's not pointless to check TT while stationary but it doesnt tell the whole story because there are myriad contingencies.

It gets even worse on load based processors like the T4 and U4's.

Datalogging is about the only way to know for sure.
 

93gtmustang

10 Year Member
Oct 21, 2006
524
43
49
Aug 6, 2007
#8
  • Aug 6, 2007
  • #8
I called Ford Racing.
They said just as rj95svt stated.
On a fuel injected car the computer does the advance at total timing.
The only way to change the way the computer does this, is to have it tuned with a chip.
On a efi car, you just set the timing at idle with the spout out.
 
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