Timing Jumping all over

[onefastmustang]

My wife bought me this really nice timing light for Christmas. I went to use it tonight to set the timing on my cobra but its jumping all over from like 12 to 4 and back again. Whats up with that???

[mickmate]

Check for play in the advance mechanisms and the distributor shaft.

[onefastmustang]

Actually I just tried it with my old timing light and its fine with that one.. Then I tried the new light on a different car and it seems fine on that car. Maybe it doesn't like my MSD ignition?

[patrickt]

Originally Posted by onefastmustang

Maybe it doesn't like my MSD ignition?

It doesn't. Some timing lights simply won't work with your (or my) MSD. The 25 year old Sun Inductive light that I'd used for years did the same thing -- I ended up buying the MSD light, although others have reported that a $29 Sears light will sometimes work just as well as the more costly MSD one.

[Tim Brewer]

It's because you're using a timing light with a adjustable timing knob, which allows you to set advance eisier on NON MSD systems. The only timing lights that work with MSD systems are the basic, standard "cheap" timing lights.

[Calbullet]

newer timing lights do not like the MSD. something with the multi-spark.

[car4jim]

I have a 1970's era Sears timing light (bare-bones) and it seems to works fine with my MSD ignition. Whatever works!!

[patrickt]

Originally Posted by car4jim

I have a 1970's era Sears timing light (bare-bones) and it seems to works fine with my MSD ignition.

Probably got it for less than $29 too!

[wtm442]

Close the gap on the #1 plug down to .025 and try it. Sometimes the wide spark plug gap has a detrimental effect of some inductive timing lights (... like the one I have).

[jrjmac1]

I also use an older Sears timing light and it works fine. Probably a new basic one will work too.