I have an 88 Camaro, 305 tbi with T5. I'm getting so aggravated with this problem.. A few years ago the old original distributor was so badly corroded and falling apart, it literally twisted apart when I went to start it one day, reluctor /magnetic pick up broke into pieces as the shaft twisted. Pulled it, found tdc, all that stuff, dropped in a complete Pertronix unit, fired up, timed it, ran good, but when I checked the cap, you could see the rotor was barely even sparking the lead edge on the cap terminals.

I've tried adjusting the timing, (esc unplugged of course, normally I run the base per stock at 0°) I've advanced the hell out of the distributor as well as retard, it makes no difference, the spark still fires way before the terminal, causing the spark to jump a pretty big gap, but then my timing will be all screwed up on top of the spark firing prematurely. I read about rotor phasing, but that whole thing seems to only apply to vacuum-advance/non-esc distributors. I do not believe this was an issue prior to having to install a new distributor.

I'm pretty sure this is causing a weak spark, leading to unburned fuel in the cylinders. Either way I know it can't be health for an already tired engine.
Any help at all would seriously be appreciated sooo much.
I also have a video I can post of it running with the cutaway cap on it if that would help.
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I have an 88 Camaro, 305 tbi with T5. I'm getting so aggravated with this problem.. A few years ago the old original distributor was so badly corroded and falling apart, it literally twisted apart when I went to start it one day, reluctor /magnetic pick up broke into pieces as the shaft twisted. Pulled it, found tdc, all that stuff, dropped in a complete Pertronix unit, fired up, timed it, ran good, but when I checked the cap, you could see the rotor was barely even sparking the lead edge on the cap terminals.

I've tried adjusting the timing, (esc unplugged of course, normally I run the base per stock at 0°) I've advanced the hell out of the distributor as well as retard, it makes no difference, the spark still fires way before the terminal, causing the spark to jump a pretty big gap, but then my timing will be all screwed up on top of the spark firing prematurely. I read about rotor phasing, but that whole thing seems to only apply to vacuum-advance/non-esc distributors. I do not believe this was an issue prior to having to install a new distributor.

I'm pretty sure this is causing a weak spark, leading to unburned fuel in the cylinders. Either way I know it can't be health for an already tired engine.
Any help at all would seriously be appreciated sooo much
Here's a video of it running with the cutaway cap .

 

Is it misfiring? On EFI/TBI change in timing does change the rotor position. Does the Pertronix distributor have a rotor with slotted screw holes? It could be out of adjustment.

 

Maybe something about the pick up coil is off..

Have you tried calling Pertronix?

 

I cut a window in an old cap on my pickup. That spark travel is normal with electronic ignition. The old mechanical systems actually moved the pickup point for the advance, nothing moves in the current stuff. Strange, but at startup the rotor pretty much points at the terminal or something is way off. And there is some built in advance in the ignition module itself IIRC.

 

It does misfire most of the time, seems worse when it gets warned up, mainly at idle and it sounds like it's multiple misfire in a row, but maybe 2/5 times it'll run smooth no missing at all. No screws or slotted holes. Nothing adjustable. I did notice a slight bit of rotational play in the shaft, and the rotor itself has a very small amount of play on the shaft itself.

I probably should've said in the first post that I also have a complete autozone generic distributor that I swapped and had no change.

 

ULTM8Z is on the right track. Ignition events are dictated by the pickup coil and reluctor. Their relationship to the rotor is a function of how/where they are assembled. You can adjust the base timing for the rest of the decade if you like, but it will make no difference with this phenomenon.

If the spark is that far advanced (in relation to the cap) at idle, it's probably only going to get worse are cruising speed since the timing can go as far as 48° BTDC in highway cruise mode.

Perhaps the aftermarket/foreign dies and fixtures used by this "PerTronix" company are not the same as those used by AC Delco when the original was made.

 

Looks normal to me. I use a crank trigger on my engine so rotating the distributor does not change the ignition timing however I still use a cap with a cutout to check to see where the rotor is phased. I want the rotor to just reach the leading edge of the cap post as the plug is being fired. This allows a bit of lead time to allow the rotor to sweep past the post especially with a multi fire ignition system. My distributor is locked out so no mechanical/vacuum advance. Other than using a start retard, my timing never changes but it also doesn't see any street usage.