Wideband Readings

[DirtDonk]

In a way, it's always timing related. But the amount of timing change that it takes to make a difference, and where your engine likes to run timing-wise, can depend on everything else around it still.
Such as, which cylinder heads and pistons you choose (combustion chamber shape and compression), which camshaft you use (dynamic compression and amount of fuel/air being introduced into the combustion chamber) and carburetor jetting (how lean or rich the mixture trying to burn is, and when, depending on jet size, metering rod profile, and spring tension) and all that.
So yes, it's absolutely timing related. But you can change that characteristic in many cases by how much fuel is coming in with the air.
With no other changes then, retarding timing is the go-to method for reducing pinging. Changing the timing curve can also change where your base timing is set, meaning you might not have to retard the timing as much to get it to stop pinging under different conditions.

Paul

 

[nvrstuk]

...and this is what I what I was saying the other day... how much timing can you or do you want to pull back ( many don't care), but some will run dyno pulls to see if they are willing to give up the timing for the hp they are typicaly losing by having to retard the timing curve so much.

The typical remedy for having the best of both worlds (better mpg and hp) is to run higher octane fuel.

Running a fully mechanical distributor was a fad back in our day for more hp. My buddies and I jumped on it as we were always looking for "free hp" and we lost several mpg (and more) along with streetable hp because we didn't have vacuum advance.

Just saying you will lose power and mpg by having to pull "too much" timing to eliminate pinging. Drawing that line is your decision.

 

[Broncobowsher]

The good tuner,
Run as little timing without giving up power. If you try 32,34,36,38 and 34 and 36 both make the most power, the correct answer is 34.

Full throttle tuning is easy. Part throttle tuning is hard. Since vacuum reduces cylinder pressure, you can run more timing, thus vacuum advance. But where is that line of too much advance? With reduced cylinder pressure you rarely have detonation being the limiting factor. You just loose power and economy if there is too much or too little. That is where you just get it close and call it good. And why there is so much tuning done on OEM EFI on the ignition side of things. Air/fuel is easy to tune, ignition is hard.

 

[nvrstuk]

Yup, yup, yup yup and YUP.

Like I posted earlier I ran as little and as much timing as possible and I just solved the light pinging at 1600rpm at 45mph under very light load by throwing in at least 10 gal of 92 octane in my 23 gak tank of 89 octane. That was the 418 designed to run on 89.

460 is a different animal and 32degrees max with straight 92octane.

Keep tweaking the timing-you have some good options.

 

[gr8scott]

Will do, thanks guys.

 

[blubuckaroo]

You've got a balancing act with air/fuel mixture and timing. When tuning mine, I found that getting to an ideal 14.7 isn't realistic in a real world. Driving conditions, elevation, and temperature and humidity all come into play. Your engine can live with a slight bit richer, but not leaner. Too lean and you're going to run into drivability issues at some point.
If you string a vacuum gauge into the car with you, you can identify which circuit the carb is in when the ping happens. If it's at the transition where you move from idle to cruise, or from cruise to power, you can deal with it with a jet/metering rod change.
In my experience, too light a step-up spring would create a flat spot but not a ping.