I installed a msd cap today and the low ohm bronze bushing. My innova 5568 dial back timing light now jumps all over when trying to use the dial back option. I believe the low ohm bushing is what causes this. I read somewhere that swapping out #1 spark plug wire with a stock type wire will help the dial back feature work correctly.
It worked great until I put the low ohm bushing in the HEI cap. I also had super low resistance spark plug wires to begin with. The manual that you can download from innovas website said that an oem wire may have to be used to make the light function properly. I'm only having issues when I try to use the dial back feature. I love the light otherwise.
Alot of dial back will work with msd when reading steady rpm.......most digital model will really lag behind if the throttle is snapped. Read your timing at 2500, snap the throttle with light on and the instant you snap the throttle watch you timing look like it retards for an instant....its just the light trying to catch up. So also go wonky at idle with the several spark per cylinder
I was tuning at the track years ago after installing MSD Dig 6. Tried my Snap On dial back then compared to 2 others. One was Craftsman. All 3 were different. So now I just use a Flaming River D cell battery operated one with balancer marked at 30. Not taking any chances on timing being 4 deg off..... Checked a buddy's and he thought he was only running 32 but it was 36....too much for me.