[71350SS]

A lot of people have these timing lights and use them even though they are supposed to affect engine timing the wrong way.This guy uses it on his Dyno sessions without worrying about it.I know some people that is the only timing light they have.

So here you are and you can make your own choice as to where setting timing is concerned.You can skip ahead to around 15:45 where he checks & re-sets the timing (dist came loose).

 

[oldcutlass]

I use my old late 70's Craftsman dial back and never had an issue setting it to 36, revving the engine to see where I am looking for zero on the timing indicator. It has always been accurate.

 

[sz0k30]

MSD and other dial back timing lights work on GM HEI ignitions which this engine has. The problem with dial back lights seems to be with MSD ignitions.

 

[68Chevele]

I have an old vintage Snap On dial back timing light. It had always had spark scatter with my MSD's and then as you rev the engine the timing would always retard. One day I pulled out my old trusty Craftsman non-dial back timing light and put it on the car to test, rock steady and timing does not retard when revving the engine. That Snap On box is pretty dusty now.

 

[SSJohn]

I have a modern innova(?) dial back light. After reading all the bad press from one individual on this board I bought some timing tape and stuck it on the HB. Guess what? NO difference in numbers between my dial back light and timing tape. This is with an HEI. I ran it up to 4500 and the numbers stayed true no matter where I had the light dialed to.
One degree on the light equaled one degree on the tape.

I was going to post my findings here but didn’t feel like it would do any good, seeing how that one individual is very bitchy about not using a dial back light on anything HEI.

 

[hydro462]

All you need to do is get your trusty machinists rule and measure on the timing tab the distance from 0 to 10. On my 78 454 its 3/4".. Then make a mark on the damper 3/4" before top dead center with a hack saw.

 

[Georgia69]

Unless building a numbers-matching show car, just use a good quality fully degreed aftermarket balancer. No need for dial-back timing lights nor measuring with a machinists rule

 

[71350SS]

Yes the MSD ignition has a direct effect on the timing light.Don't forget every timing light is triggered by the spark being delivered to the ignition wire and then on to the spark plug.So the MSD's multi-spark feature is most prevalent at idle speeds and lower rpm's.
So of course, it is going to affect the timing lights flash time and in doing so will affect the way people set their timing.There is nothing mysterious about it,just plain cause and effect.
I'd be interested to know how many people use a dial back with their MSD ignition anyway maybe because that's the only light they have or whatever their reasons.

 

[David Ray]

Amazing, so many have NO idea as to dial back and what it is actually designed for.

Dial back is a correction device to reset the timing correctly when an ELECTRONIC timing curve is used in an EFI system, because there is computation lag while the EFI computer computes the timing setting as the engine runs.

Oddly enough, there is NO computer lag in any analog distributor (using mechanical, and or vacuum advance curves) so, granite heads, since there is NO COMPUTER LAG IN AN ANALOG SYSTEM, NO TIMING LIGHT COMPUTATION LAG CORRECTION IS NEEDED/USABLE

Also, MSD multi-spark does not compute timing, it fires the initial analog timing, then creates more timing events after that. As RPM's rise, the number of multi-sparks reduces to one spark per event, per cylinder after around 3K RPM's. There is NO computer timing correction, they first fire as the distributor advances tell them to.

And, on the useless final tune device known as a dyno, it gets even worse, they never time, nor jet correctly for street use, only for power contests with other dyno heroes. Dyno's are GREAT parts systems development tools, abysmal as a final tuning device.

The great part of a dial back system is, the dial back works with an EFI computerized timing curve, and when sensible people that actually think of the way it actually works, can leave the dial back dial OFF, to work with analog systems.

Look up the definition of "Whirling Dervish", more than a few that believe a dial back is so special for an analog system, are whirling in circles dancers..

As I said, AMAZING.

 

[oldcutlass]

Dave, what electronic control devices were around when I bought my dial back timing light in 1977?

 

[SSJohn]

And in he comes to wreck this thread. And dynos are useless, lol.

 

[71350SS]

This is a good article and takes some of the mystery out of an electronic device.

The lost art of servicing GM HEI

Any conversation about electronic ignition leads to the GM HEI, which is an abbreviation for high-energy ignition. Chrysler was the first company to offer electronic triggering to the masses; it...

www.hemmings.com

Basically it covers the service part of the HEI.

 

[David Ray]

I guess the granite syndrome is wide spread. So, no electronic fuel injection in Europe back then? I cam think of at least 5 that used those dial back features.

It has long been proven that a dyno is not a final tuning device, GREAT parts development tool, not a seat of the pants device for final tune.

SSJohn, I have been in the ignition system industry for over 4 decades, and even worked for GM in the HEI and other electronic systems design and development programs, and NOT ONCE, DID I EVER SEE YOU ANY PLACE THERE. NOT ONCE. So, stick your attitude where the moon don't shine.

Now, please, someone want to expound on just how an ignition curve that does not compute a first spark per firing event, needs to be electronically corrected for the electronic firing point IT DOES NOT HAVE, because, I am confused. Don't we all agree, the dial back feature is there to correct computer computation timing lag and inaccurate first firing points, right???????????????????????????????

Last time I looked, an MSD 6 series box only read what the magnetic pickup sent it for the first spark of the cylinder it is working with, and AFTER THAT, the timing does not matter, the first spark of the analog, never deviates from electronic computer computation, fires when the pickup says to, by the mechanical/vacuum advance curves.

Where is the electronic curve timing settings from the timing computer, that isn't even on the car????????????????????????????????????????????????????????????????????????????????????

Wake up, everybody, dial back is not for analog systems.

 

[oldcutlass]

Dave what am I reading at 3000 rpm with the dial back set to 36 and the harmonic balancer lined up to the timing tab reading 0?

 

[shovelrick]

The race engine/dyno shop owner told me to bring my car in after I installed the engine so he could tune it, this was after the 5-6 pulls he did and got the 600 ft lbs I was hoping for and that was on his new Super Flow dyno, the only tuning he did was give the dist. a small twist without a timing light

 

[SSJohn]

Dave/aka ignition man/aka whatever you’re calling yourself, answer oldcutlass. Tell us why his works in defiance of what you say. He’s asked the same question twice now, why are you ignoring him.
If you answer, which I doubt you will, leave the god complex at the door.
Try to use big boy words and not insults.

 

[chaze]

When I compared a dial back reading of the timing on my stock GMPP HEI (no added spark box) to the readings without the dial back feature while utilizing a timing tape....

Both readings were the same.

 

[SSJohn]

When I compared a dial back reading of the timing on my stock GMPP HEI (no added spark box) to the readings without the dial back feature while utilizing a timing tape....

Both readings were the same.

Mine acts exactly this way. So that’s three of us. But we are wrong, our timing lights are wrong. Just wait, Dave/aka ignition man/aka whatever will tell us we’re idiots and don’t know what we’re talking about.