Typical Timing?

Not sure, but I'd guess you could run closer to 34-36 total. My old stocker w/ a mild cam ran 16 initial and 36 total.

Pull the vacuum line off the distributor and block line. Loosen distributor. Start engine. Raise RPMs to around 1000 to 1500, keep the RPMs at the same place and turn the distributor one way until it sputters a little, now turn it the other way until it sputters a little, these would be your limits. Now set it somewhere in the middle that sounds the best to you. Hold distributor in place and shut off engine. Tighten distributor. Hook up vacuum start engine and check timing. What ever it says is YOUR engines timing.

Timing depends on a few things, Vacuum and mechanical advance, Timing chain slap, spark plugs, Coil, Points condenser. Even plug wires.

Oh9mustang has it; every engine is a little different and you're best bet is to set it to whatever makes said engine run the best.

I am not sure that is the best way to go about it. It may get initial timing right, I don't know. It definitely is not the best way to set total timing. My smog duraspark had 36* of mechanical advance. I ended up welding and grinding the window in the mech adv to get it down to 16* and initial at 17* gave me 33* total.

Initial timing for a 306 with an F cam should be a minimum of 12*. It will probably like more. You may be limited on initial timing by the amount of mechanical advance in your distributor. To get it right will likely require changing the amount of mechanical advance to allow enough initial to get good throttle response. The good news is any distributor can be easily modded with the help of google and a little ingenuity.

oh9mustang said:

Pull the vacuum line off the distributor and block line. Loosen distributor. Start engine. Raise RPMs to around 1000 to 1500, keep the RPMs at the same place and turn the distributor one way until it sputters a little, now turn it the other way until it sputters a little, these would be your limits. Now set it somewhere in the middle that sounds the best to you. Hold distributor in place and shut off engine. Tighten distributor. Hook up vacuum start engine and check timing. What ever it says is YOUR engines timing.

Timing depends on a few things, Vacuum and mechanical advance, Timing chain slap, spark plugs, Coil, Points condenser. Even plug wires.

Click to expand...

You have got to be ****ting me right? This is how we find out what a motor likes for timing. ARG!

Depends on heads, cam, etc.

Good (safe) baselines are 10-12 initial and 30-34 total... (all in by 2000-2500)

- heavier car, less torque, less rear gear: bring it in a little slower
- lighter car, more torque, more gear: you can bring it in sooner

Old 60's style heads will like more total lead cuz of inferrior designs.

Early/mid 70's heads *can* need a TON of lead cuz of huge chamber size (low comp) and no quench (dead air) ...as much as 40 degrees!!!

Good modern heads will make peak power with less lead due to better chamber design, smaller volume, etc... (30-32 degrees total)

Also for example, if you run flat top pistons at a given compression you will need less lead than if you run domed pistons at the same compression. (the flame front needs time to climb up over the dome, instead of just running strait across the flat top)

If you have a source of good fuel, you can of course get away with a little more ignition lead.

Or if you have alott of cam, sometimes you can run a little more initial lead, cuz the overlap will bleed off some of the cylinder pressure at low rpm untill it "comes on the cam"

If you have aftermarket heads, call their tech support guys and ask them what they have found is best for X head on X engine with aprox X compression.

Chances are they have dynod thousands of engines in testing their heads/intakes/etc... if you can find one of their guys who is willing to tell ya, you'll be real close.

Otherwise its trial and error on a dyno.

(all numbers and testing shoud be done with vac adv unhooked and plugged, then if you've got adjustable vac adv you can set it to add 10-15-20 aditional degrees for light load cruise...)

Oh, I almost forgot...

If you find you're having trouble starting it (like it's working really hard to turn over... working against itslef), try less initial lead.

If it starts but idles like total s*** - rough, broken, wants to die, overheats... put more initial lead in it.

( when I say this I mean like try changing it 2-3 degrees at a time or something, don't go banzi... maybe a MAX change of 5 degrees at a time. )

You'll also probably find that as you dial in the timing that the motor likes best, you'll also need to make minor changes to jetting and idle speed / mixture settings.

( just a few of the reasons that a GOOD dyno tuner is worth his weight in gold, when building a new motor... )

Hope some of this helps.

Dave-

Again - try 10-12 initial and 30-34 total, in by about 2500 as a starting point... that should at least get you fired up and running.

I'm pretty much a lurker on stangnet mostly because of how i feel about the uniformed hacks handing out expert advice. People like oh9mustang are a real problem! He knows just enough to be dangerous! That said 0h9mustang sometimes its better to keep your mouth shut and let people think your a fool rather than open your mouth and remove all doubt.

Also after you get it up and running...

(ass-u-me-ing you have a tuneable distributor)
It should come with a half dozen different color springs. You mix and match these to get the desired "curve" you want, for the mechanical advance in the distributor. Or the nice modern ones, just have a dial you turn on the side of the housing... cheaters!

Anyhow, you can put it on the dyno, on the strip, use the seat of the pants, whatever...

Say you have 10 degrees initial advance and 22 degrees of mechanical advance in the distributor, for 32 degrees total timing:

Then you bump it up to say 15 initial: you notice it idles better, it's peppier down low around town, but feels just a bit "off" on the top end or it *pings*...

Well you can use this info to tune by:
1 the motor likes more lead down low / mid rpms
2 youre on the ragged edge / a little too much up top *feels flat and pings a little*

- so you know it wants more initial timing, but you're a little overboard with 37 total (you had 32 but then you added 5 more in initial)

- so change the springs in the distributor, or dial back the dial on the side of the housing, whatever you have... so that you only have say 20 degrees of mechanical advance in the distributor and leave the 5 extra degrees of initial advance in.

Now the motor will have the extra initial lead that it seems to want, but you've backed the mechanical advance off a bit so that your total timing is not so high.

- you come out with 15 initial, 20 mechanical in the distributor for 35 degrees total timing. (plus vacuum advance if you have it)

The reverse of the above is also true, if you need to just apply the same principles in reverse.


If you do have vacuum advance that's tuneable, that adds another variable... but for the most part it will only be noticable in two ways:

1 if it pings on light throtle acceleration, or pings momentarily while transitioning from light throtle cruise to acceleration. (a little too much vac adv, back the vacuum advance off maybe 4-5 degrees)
- *some of the vacuum advance units have a little-teeney-tiny screw inside the hole where the hose goes on, that you can turn to adjust how much advance it adds*

2 if your gas milage sucks just as bad as it ever did without any vacuum advance... or your milage is equally bad wheather your in town or on the highway. ( not enough vac advance / not working at all, check to make sure it's hooked up, diaphram not blown, etc... )


Again, hope this helps somebody.