Author Topic: Initial Advance - How Much Is Too Much?  (Read 1271 times)

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fe468stroker

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Initial Advance - How Much Is Too Much?
« on: August 05, 2022, 11:53:49 AM »
I know that the FE likes more initial advance than Ford recommended.  At the 6* factory setting you can tell that it is held back.  With modern day equipment ( side oiler block, aluminum heads and roller cams etc, is there a rule of thumb as to how much to dial in on a 3600 lb vehicle?  In the old days you would advance it 2* until spark knock was heard then back it down until it quits.  But in some cases you can't hear spark knock because of exhaust noise and/or solid cam noise.  Want to get all the power potential without damaging the engine.

TomP

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Re: Initial Advance - How Much Is Too Much?
« Reply #1 on: August 05, 2022, 12:21:44 PM »
On my Fairlane I went to a crank trigger. The distributor is just a shortened shaft holding the rotor. So it has 38 degrees all the time. It's a race car and normally runs down the track between 5000 and 7400 rpm but drove around the pits at 1000rpm with great throttle response. I used a toggle switch for the ignition after cranking it with the key for a second but it will fire up fine even leaving the switch on.

Heavier cars and smaller engines make use of timing advance but even on my truck i'd set the total at 36 degrees and not really care whatever the initial was. Usually around 14.

pbf777

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Re: Initial Advance - How Much Is Too Much?
« Reply #2 on: August 05, 2022, 03:33:34 PM »
  In the old days you would advance it 2* until spark knock was heard then back it down until it quits.  But in some cases you can't hear spark knock......................


     This is 'still' actually true, and the statement was back-up approximately 2 degrees from the threshold to cover for the non-audible detonation; but better was to at the track (drag-strip) start with conservative timing values, add 2 degrees with each pass, keep adding as long as it picked-up, then when it either didn't go faster or particularly if it slowed back up the 2 degrees; as the engine will generally lose power before you'll hear the detonation!   :o

     Be careful of lock-out ignition timing advance for low speed (engine) detonation when tooling around and transitional throttle actuation particularly at low revolutions, and is probably not recommended for street use.   ;)

     Scott.

     

cammerfe

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Re: Initial Advance - How Much Is Too Much?
« Reply #3 on: August 05, 2022, 10:31:58 PM »
Factory mechanical-advance-only distributors came from the factory with the ability to use either 15 or 10 degrees and came with the 15 in position to start with. The old originally 'standard' way to do your set-up before your first trip to the digs was to change the setting to the 10 degree slot in the mechanism. And if you had access to the best Sunoco fuel, you could then turn-in until you had an additional 18 or so. (Remeber that we have two sorts of 'degrees' in this discussion. The 10 and 15 marked inside the distributor were factory nomenclature and actually had to be doubled to get the actual result.)

Depending on details such as ambient temperature and how good your gas was, etc, the 38 you'd have by using the 10 degree end---actually 20---the 18 you got by turning the distributor might work just fine or, perhaps, make the engine hard to start.

As a very loose generality, the more the better, unless you were causing yourself problems.

KS
« Last Edit: August 09, 2022, 10:29:48 PM by cammerfe »

gregb

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Re: Initial Advance - How Much Is Too Much?
« Reply #4 on: August 06, 2022, 11:44:12 AM »
I don't have aluminum heads, but I run 14 initial and 36 total.....I got that by advancing it until it idled well and the starter didn't struggle, and then just limited the total so it's 36 at 2500 rpm....

fryedaddy

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Re: Initial Advance - How Much Is Too Much?
« Reply #5 on: August 06, 2022, 10:06:36 PM »
on the street with a msd dist.and alu heads i use the 20 bushing and 13 initial.when i had cj heads i used 20 bushing and 18 initial.
1966 comet caliente 428 4 speed owned since 1983                                                 1973 f250 ranger xlt 360 4 speed papaw bought new

fe468stroker

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Re: Initial Advance - How Much Is Too Much?
« Reply #6 on: August 07, 2022, 11:35:37 AM »
I am running the Unilite non vacuum advance with Accel spark box.  Playing with the initial advance I don't hear any detonation running the engine to 4K sitting in the garage no matter how much is dialed in.  Does get to the point that there is not a miss as such but running rough if it goes too far.  After many years of operating noisy machinery my hearing is challenged to say the least and I may not hear spark knock over the exhaust and other engine noises.  Right now it is set at 16* initial and 38* total but still seems a little rough.  I want the full potential of the engine without doing any damage.  This is a street warrior only so test and tune at a track won't happen.  If anyone has close to the same combination (side oiler, aluminum heads & 2 X 4 intake) in a Mustang and figured out the ideal settings I would appreciate the figures.

1968galaxie

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Re: Initial Advance - How Much Is Too Much?
« Reply #7 on: August 07, 2022, 04:20:10 PM »
At low/no load conditions an engine will run at 50+ degrees of advance.

Max advance 38 to 40 degrees.
Initial will depend on the amount of mechanical advance in the distributor.
If you have 30 degrees mechanical advance - then maximum initial will be 8 to 10 degrees.

Find out what the mechanical advance is for your distributor then work from there.
Or get it re-curved by someone who knows what they are doing.




Falcon67

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Re: Initial Advance - How Much Is Too Much?
« Reply #8 on: August 08, 2022, 11:09:10 AM »
On my Fairlane I went to a crank trigger. The distributor is just a shortened shaft holding the rotor. So it has 38 degrees all the time. It's a race car and normally runs down the track between 5000 and 7400 rpm but drove around the pits at 1000rpm with great throttle response. I used a toggle switch for the ignition after cranking it with the key for a second but it will fire up fine even leaving the switch on.

About same on my Falcon.  The old Mallory used a 10 degree start retard and the current 7AL-3 has 25 degrees built in that turns off at like 900 RPM.  It doesn't always seem to engage LOL, so also same - switch to crank, ignition on once it's cranking good.  Over winter, I bypassed the key, but it stays in the ignition lock because thats how I get in the trunk for the fuel cell LOL

cleandan

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Re: Initial Advance - How Much Is Too Much?
« Reply #9 on: August 09, 2022, 10:03:47 AM »
Initial advance is usually detected when your engine is hard to crank over at start up, very often being sensitive (harder to start) when everything is fully hot and heat soaked.

This means you should be certain your start circuit is good.
Battery is good, all electrical connections are clean and sound, and battery/starter cables are proper gauge and in good condition BEFORE deciding you have too much, or not enough, initial advance based on how easy it starts hot.

The more inportant aspects of ignition timing are total advance and the advance curve.
Learn to read your plugs. Modern electric ignitions make this more difficult, but still viable.
Learn how to do a "shut down run" and find a good place to do them.

Find the total advance and advance curve your engine likes and stick with that.
Once you know the total, then you can dial in the intitial to suit your car.

As a general starting place FE's like the 32-38* total advance, 12-18* initial, and a moderate curve that starts around 1,100 rpm and is all in by about 2,800-3,200.
Of course this is a guesstimate because your specific engine build paramaters will determine the needs.

Start with total advance, read the plugs after a shut down run looking for signs of detonation.
Advance until you see signs of detonation, then back off 2*...make another shut down run...make adjustments...lather, rinse, repeat until total is found.

Then move on to advance curve.
Once the curve is right you are likely at your initial setting by virtue of other parameters being set...but if you find you need less initial you must make adjustements and reset total.

If you find you can take more initial you must make adjustments and reset total.

A proper initial will clean up idle, improve starting, help with plug life around town and cruising, and can even increase economy if you don't have a vacuum advance distributor, but it is the least important of the advance adjustments.
1) Total advance
2) Advance curve
3) Initial advance
4) Vacuum advance

Last, be certain your carb is set up right before going too deep with the advance tune.
Very often I begin my timing tune sessions with a carb adjustment, but this can be a bit of a double edged sword because many "carb issues" are are actually ignition based.

e philpott

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Re: Initial Advance - How Much Is Too Much?
« Reply #10 on: August 09, 2022, 02:53:09 PM »
Big cams like more Initial timing from what I see, my own 416 with 266/276 at .050 cam likes 18 to 20 initial , 36 total with Ebrock heads