ive never found the dial adjustable lights to be accurate w/ the hei and other ignitions with a lot of rfi. absulte repeatable results w/ non adjustable lights of many brands... even the least expensive ones.

FLUKE, The best electronic testing equipment

I just have an old ass non adjustable snap-on that was my dads that I use. I did have an actron adj. that worked well too but It was closed in the hood of a car.

MSD sells a nice, non adjustable light that is battery powered. No more power cables to get tangled up in the fan belt!! I have one and I really like it. It's especially good when trying to get timing readings while the boat is cruising and I am leaning into the engine compartment.

A several years back I bought an Innova digital timing light from.....don't laugh.....JC Whitney.
Best damn timing light I ever had. The digital advance is easily dialed back, has digital tachometer, reads voltage and whole buch more features.

Depending on what kind of distributor you are using, you may need to put it in "Base Timing Mode". You may be able to temporarily disconnect the CDI box and reconnect the stock ignition to set base timing. That's the way I like to do it.

Dave

My snapon digital timing light goes crazy and is eratic on my msd/hei efi motor,I use a cheap battery powered non dial back type like the msd one,works the best,Smitty

My Snappy has no problem, I'm pretty sure it is rated for HEI and multiple spark ignitions, as they are in almost all new cars.

I'm sure we both have the same light,fancy digitial one with tons of features,mine has never worked well on my boat motor though,works great on new trucks and cars though,Smitty

Put my Sear's timing light on all my cars over the last few days and finally figured out it is acting up and was sent off for repair. It had worked well until last Sunday when I guess it started going bad intermittently. I had a motor missing and when I hooked the timing light up to check timing the light would not blink on 1, 3, 6 plug wires which led me astray on my troubleshooting. Turns out it was a stuck float on the Holley. But, the timing light took me on a long dead end trail before dumping me off with more broken than when I started so I was pissed off at the light.

BTW, I can not read the advance marks on my balancers. Since it sounds like a non-adjustable light is more reliable, how can I mark 34 or 36 degrees on my balancer accurately to time with a non-adjustable light?