Hi All,

Rather than hijack another recent thread discussing timing, I post my question here; I have heard multiple people discuss issues when using their timing light and an MSD 6AL type box. I would like to know what those issues are. I have been chasing my tail over timing issues, and want to verify that I am not seeing errors in readings due to the MSD. I'm using a recently purchased dial-back digital display timing light with RPM - it appears to work very well.

So, any pointers would be appreciated - many thanks.

Setup is MSD billet distributor (tach drive) with 6AL box & MSD coil, all direct new wired, removed resistor wire.


S.

 

The MSD produces multiple sparks at low RPMs and the timing lights thus do not give accurate readings. MSD has suggestions on their site as to what timing lights to use.

http://www.msdignition.com/page.aspx?id=3306

 

I use an old snap-on timing light for MSD. The one you have should be sufficient.

http://www.setyourtiming.com/video.html

 

Great - I think this is the factoid I am looking for. I get no 'walking' of the reading at idle due to multispark so my dialback light must be good to go.

Thanks to both for the replies.

 

You did read that MSD clearly states not to use a dail back light?

 

I have an all MSD system (dist, coil and 6AL box) and my old Snap-on dial-back timing light works fine.

 

The multi function digital dialback light won't work on our 6AL, the old Snap-On analog 30+year old light works fine.

 

What timing "issues" are you actually having? The dial back may or may not be be working very well as you stated.

 

Thanks for all the replies. I think I am good. my timing light works very well, no jumping around at all, stable, dial-back works perfect or appears to. I was concerned with getting a false degree reading - but that does not appear to be one of the symptoms.

The problem I was having is simple. Using Lars sheet, set my 'all in' mechanical timing (sans vacuum advance) to 34 degrees (being very conservative), reconnected my vac advance and I occasionally get pinging under acceleration. Can not figure it out but I now suspect it's my advance can is too aggressive (it's a B26) - my 468 produces excellent vacuum at 18" and I think it's too much for the can - when I get 'on it', the can does not release quick enough and the combined timing must be too high for it to detonate like it does. I also have been experiencing a rough idle but have no issues with immediate pickup, she really responds to a heavy right foot except for that F&*%ing occasional ping!

So, I was hoping that I was not chasing my tail (and setting too hgih an advance) when it came to setting my mech timing via a bad reading on the timing light due to MSD & digital dial-back incompatibilities.

Again, appreciate all the advice. Right now I am looking for a 'stiffer' can (experts please comment). Previously, the vacuum was hooked up to a non-manifold source with the result of my temps creeping up to about 215 at idle. The car, with Dewitts radiator and vac advance connected correctly always is now at 195-200. Perfect, except for that ping!

 

Lars has a great paper that lists can specs.

DC

 

I swapped my can per Lars instructions to the B28 if I remember correctly. I think its rated at 16 degrees advance, but mine tops out at 14 max. Helps with the idle especially with the bigger cam I got. Check your springs. You might have your advance coming in to early. Mine comes in all at 2800-3000 rpm. Before I was to low at 2300 rpm.

 

I've got a MAC dial back light, circa 1980 that works fine. The timing light on my SUN machine works fine too, but the multiple sparks drive the scope itself absolutely crazy.

 

Yeah, I am running the heaviest springs right now to ensure that was not the issue. It's the can, I am fairly sure.

I was aware of Lars' paper - very useful. There's a companion paper that Lars references (and includes) that addresses the rule proposed by the engineer; that the vacuum canister should be at max advance at not less than 2" below idle vacuum. the B26 is all in at 6-7", seems too low for my application. I will report my findings here.

thanks all, disgnosis this weekend, fun fun fun.

S.

 

This is seemingly an old thread, but I'll add my two cents.

Here are some Engine issues that my timing light told me about .Spark scatter due to badly worn distributor shaft with points ignition. (Dwell meter would have pointed this out too,)
Upside down centrifugal advance weights.
Worn centrifugal advance mechanisms.
Seized mech advance mechanisms.
Pooched vac advance canisters ( with mityVac pump).
Outer damper ring slipping.
Vacuum advance canister installed where a pressure retard canister was called for ( Turbocharged Corvair).
Adjusting a few centrifugal advance curves.
Testing coil wires, dist cap and rotor in No spark at plug situations.
Testing for spark in intermittent electronic ignition module failure situations.
Setting ignition timing of aftermarket CDIgnition on dirt bike that required repositioning the magneto rotor and running key-less.

As far as accuracy, it's always a nagging worry. The best I have is comparing 2 lights like this https://mechanicguides.com/best-timi...-msd-ignition/ after a wary informational static timing check when possible, since worn components can allow several degrees change when running. The old self powered orange Xenon light my dad gave me over 40 years ago seems to be pretty consistent so far.nce I run MSD unit .I use a non dial back light, since the digitals won't work on MSD, and a timing tape to plot curve. and BTW, always use the positive stop method to first find TRUE TDC.
Tuning articles all over the web and in mags will tell you how much @ what rpm for all sorts of engines and builds from dyno tests. Those guys with the dynos can figger out just what the engine likes better than my ear, and the closest drag strip is 60 miles away, makinf that method inconvenient at best.
So I value a good timing light highly.

All the best,Byosor