[VCho455]

Sounds to me like a cross firing issue. Easy to check the wires by either misting water on the wires while the engine is idling or using an old school test light and running the probe along the plug wires. Again with the engine idling. (The newer test lights with LEDs may not work for this test or they may only spark once. Dhoo!) No matter which method you use you need to do it in the lowest light possible so you can see the sparking.

Another thing you might want to check is the rotor phasing of the distributor which can cause spark jump in the distributor.

Both of these checks are easy and only involve a bit of labor. Plug wires are a wear item.

[70GS455]

What is your distributor end play?

Also which Advance springs? Light ones will do what you are describing

Sent from my SM-S901U using Tapatalk

[Schurkey]

Originally Posted by Verdoro 68

The Taylor wires aren't anything special. Just off the shelf cut to fit 8MM Spiro Pros.

"Big Joe" Sherman (RIP) posted on SpeedTalk that he hated Taylor wires. I don't know if there's some back-story for that. Said they killed power.
https://www.speed-talk.com/forum/viewtopic.php?t=25712

Originally Posted by bigjoe1 post_id=293349 time=1299118199 user_id=1579

Taylor was the brand that lost over 40 horsepower==SORRY


JOE SHERMAN RACING

He never mentions what model of Taylor wires were used, or what condition they were in. Read the whole thread. Some folks like 'em, some folks hate 'em.

Originally Posted by Verdoro 68

The wire going into the positive post on the coil from the wiring harness is 14.2v.

14.2 volts with the engine running?

Originally Posted by HWYSTR455

The MSD super conductor 8.8 wires are my go-to, and I make my own lengths. It's hard to find a good wire these days.

I have Super Conductor plug wires on a couple of vehicles; and I'm satisfied with them. OTOH, I've switched to Summit 8mm "house brand" plug wire kits that come with the spark plug end attached, then cut-to-length at the distributor end, and install the metal terminal and the boot. Much less expensive than the MSD wires, although Bideninflation has increased the price. Made in USA, and they come with a crimping tool. Available in blue, red, and black, I think. Various part numbers depending on the angle of the plug boots, color, etc.

There's also versions with ceramic boots, 8.5mm insulation, etc.

Example:
https://www.summitracing.com/parts/sum-860826r

[Verdoro 68]

Originally Posted by 70GS455

What is your distributor end play?

Also which Advance springs? Light ones will do what you are describing

Not sure off hand. SunTuned recently went through it an recurved it for my new setup so I'm certain it's fine. Since the plug wire swap appears to solve the issue, that also lends to the distributor being ok.

Originally Posted by Schurkey

14.2 volts with the engine running?

Just about 17v at the power lead on the coil while the engine is running at idle. Getting voltage to the distributor doesn't seem to be the problem.

I swapped coils to a basic Blue Streak this afternoon and left the Taylor wires in place. Same issue with the timing jumping. Swapping back to the Lectric wires leveled the timing out like it did before.

Interesting opinions on Taylor wires. I always thought they were decent. Every cylinder is clearly firing so they're doing their job. I measured the resistance on each Taylor wire looking for clues but didn't see anything unusual. They actually have extremely low resistance as compared to the 'Lectric wires.

FWIW, these are what I have: https://www.summitracing.com/parts/tay-73053

At any rate, I swapped them all out for the 'Lectric set since the problem seems to be pointing to the Taylor wires. Initial impression is that it runs the same, so maybe there just something about the way the Taylor wires are made that the timing lights didn't like. Every Taylor wire I tested between the new set and the old set had the same behavior with the timing light.

[kyle_blake]

my timing chain was the one sd recommended for my application. JP something ? 6 or 8 keyway, don't think it was double roller.

can one even buy the stock nylon timing sets? is that what was stock, i remember even ram air III's having them ?

[Schurkey]

Originally Posted by Verdoro 68

Swapping back to the Lectric wires leveled the timing out like it did before...

...At any rate, I swapped them all out for the 'Lectric set since the problem seems to be pointing to the Taylor wires. Initial impression is that it runs the same, so maybe there just something about the way the Taylor wires are made that the timing lights didn't like.

Are you saying the issue with the "timing" does not affect the way the engine runs?

If so, this is more of a timing light issue than an actual timing issue.

Originally Posted by Verdoro 68

I measured the resistance on each Taylor wire looking for clues but didn't see anything unusual. They actually have extremely low resistance as compared to the 'Lectric wires.

Plug wire resistance means far less than the advertising would have you believe.

"Ordinary" carbon-rope plug wires use resistance to lower the current (amperage) of the spark pulse. It's the amperage that's responsible for the radio-frequency interference (RFI). Typical "used" carbon-rope wires in good condition may have something like 4000 ohms per foot of wire, but that can increase as the wires "wear" and age.

Helically-wound plug wires have far less resistance. They use inductance instead of resistance to cut the amperage.

Either way, the spark-pulse amperage is dramatically reduced along with the RFI, while not affecting voltage too much.

I like helically-wound wires because of the potentially-longer service life of a wound-metal-wire core, vs. "carbon rope", more than an actual performance gain.

[Verdoro 68]

Originally Posted by Schurkey

Are you saying the issue with the "timing" does not affect the way the engine runs?

If so, this is more of a timing light issue than an actual timing issue.

Correct. The engine is running the same no matter what the timing light shows. It’s not changing RPMs or missing a beat at all. You can hear/see it in the videos I posted earlier in the thread.

I thought it was my timing light, but we tried four different ones including a pricey Snap On dial back.

I’ve changed the cap, rotor, coil and Pertronix module. The only thing that’s made the light read consistently is to change the plug wire the induction clip attaches to which leads me to believe it’s the Taylor wires, not the timing light.

[Verdoro 68]

More sleuthing today. I think I've boiled this down to an incompatible mix of ignition modules and plug wires.

Pertronix I & II with 'Lectric Limited wires : steady timing
Pertronix I & II with Taylor wires : bouncing timing

New curveball:
Pertronix III with 'Lectric Limited wires: bouncing timing
Pertronix III with Taylor wires: steady timing

The Pertronix III is a multi spark system so it's interesting that it works with the Taylor wires but not with the 'Lectric wires. It must have something to do with the shielding on the wires and the amount of spark being picked up by the timing light. The coil didn't make a difference in any of the tests, but I tried a Pertronix II, Pertronix III and a Standard/BlueStreak UC12.

Now that I know this, I'll likely run the Pertronix III with the Taylor wires.