Set timing while at 3200 rpm?

[john.thompson068]

Years and years ago I sent my distributor to a place to re-curve my distributor to work better with my engine combination. When I received my distributor back it had a tag that said 20* int, 34 total and 3000 rpm. I just now found the tag and on there I had written a note long ago that said bring the motor to 3200 rpm and set timing at 34*. What is the meaning behind this and should I do it? Not even remembering the tag I recently set the timing to 13* at idle because this provided the highest vacuum and easy starting. What is the difference?

 

[Cranky]

I always set my initial then check the total. If the total isn't what I want, then I work on the distributor to get what I want for the total at the desired rpm.

 

[70rr-brian]

Some start by setting total timing and let initial fall where it may. The best way to tell if your total timing is correct and maximizing power under WOT runs is dyno testing. If no dyno available then run 1/4 mile runs and see where your speed peaks and that would be optimal for your engine. By focusing primarily on intial you may be leaving some power on the table at higher RPM's. That is not taking into consideration the timing curve of course....which may need to be adjusted as well. But if you aren't busting full throttle runs on a regular basis and not trying to eeek out every bit of power you can and it is running good....then I wouldn't sweat it too much.


I remember hearing more than one person say.....advance until you start to get detonation and back her off a couple degrees and you are set.

 

[67 B-body]

I always set my initial then check the total. If the total isn't what I want, then I work on the distributor to get what I want for the total at the desired rpm.

Yep yep.... same here!!! have the initial set, then go for total, then play with the springs / weights for curve. All in by 3200rpm.
My Mallory has adjustable max travel limits for advance.

 

[Cranky]

And depending on what I'm doing with the vehicle, I sometimes want my timing all the way in earlier...

 

[john.thompson068]

Okay, how do you guys set your initial? I set mine by advancing timing 2 degrees at a time and then taking vacuum guage readings and turning off the car to see how easily it started. Anything past about 14 began yielding slightly less vacuum even though I was readjusting the idle speed and idle mixture screws at each timing setting. As timing went to 16 and 18 the starter could no longer start the car very easily so I went back to 13-14.

 

[67 B-body]

Okay, how do you guys set your initial? I set mine by advancing timing 2 degrees at a time and then taking vacuum guage readings and turning off the car to see how easily it started. Anything past about 14 began yielding slightly less vacuum even though I was readjusting the idle speed and idle mixture screws at each timing setting. As timing went to 16 and 18 the starter could no longer start the car very easily so I went back to 13-14.

I go with 15 adv at base. I think whatever works for easy start is fine for base timing in my car because my converter stalls higher than 3000rpm "full advance rpm". So you can see that it doesn't really make a huge difference to me.
Just a tidbit to keep in mind...

 

[PoppaSmurf]

I agree with Cranky...depends on the variables and the vehicle...I have mine set at 18 deg adv Int. and total of 36 at 2900 and it works for me at the track with 108 or 110 octane I'll bump it up to 20deg Int

 

[john.thompson068]

Okay, first I need to know what is meant by initial and by advance or full advance. What is happening inside the motor? So at 13* initial the spark plug fires off at 13* of crankshaft rotation before TDC? What is full advance or all in referring to at whatever rpm? It looks like it is about time I learn more about the distributor and will start to do some Internet searches on the topic.

 

[PoppaSmurf]

figured I could tell ya...but then I'd have to killya...lolol so I'll let the true literaries tell ya.... no elaboration...just straight and simple...click the link....

http://auto.howstuffworks.com/ignition-system1.htm

 

[john.thompson068]

figured I could tell ya...but then I'd have to killya...lolol so I'll let the true literaries tell ya.... no elaboration...just straight and simple...click the link....

http://auto.howstuffworks.com/ignition-system1.htm

That was indeed a good article, but I need more. So now I understand that as engine speed increases, the spark must occur sooner and sooner as rpm increases. But what is meant by 34 total at 3000 rpm. Meantime, I am off to find more Internet resources.

 

[dryheat]

The distributor has a mechanical advance with weights and springs. As the distributor shaft spins faster and faster the centrifugal force of these weights allows the advance mechanism to provide spark advance up to a physical maximum of 34* ... which in this case is at 3000 RPM.

So at 3000 you have 34* - 4000=34* 5000=34* etc.