Spark Blow-out or Detonation Need Tuning Help

[eades5.0]

On the dyno at around 5800rpm my car kicked out 3 puffs of grey/black smoke and the power fell off hard. No noise (typical det) from the motor (marbels rolling around) and the motor is still in one piece.
It was like puff..puff...puff small pause in between.

This was around 20psi, so I'm thinking the motor def woulda been hurt or heard some unhappy noise from the motor if this was detonation. My tuner is dead set on detonation because he can see detonation from the exh (new to me) but I think it was spark blow-out.
I was on Auto-lite 3923s (2 ranged colder than stock) gapped @ .035. This was around 550rw with (total timing) 14*@4k, 12*@5k, and 10*@6k on a 10.5 or so a/f no methanol. This was only on 91 octane (yeah I know) but in order to tune for methanol you have to get the car somewhat tuned in on pump gas.

Need some help.
I plan to take some boost out of it, bring my gap down to .026, and possibly try a colder plug. I am done messing with methanol and have 10 gallons of 109 Sunoco GT plus waiting to go in
Any input

Chris

[eades5.0]

331/T-trim/H/C/I

MSD Dig 6, MSD Dizzy, MSD cap/rotor/coil

[eades5.0]

Also

The a/f went in the 9s right when the car started puffin, so it seems the spark was blown out and the cylinder filled with gas hence the power drop and a/f drop.

It may have been a lil of both det/spark blow

Anyone seen detonation like this?

[eades5.0]

I think reading the plugs will tell all, I def think my gap was about .010" off as I was only expecting 15-17psi
Who knows may have been a lil det and spark blow out

[mustan5069]

Also

The a/f went in the 9s right when the car started puffin, so it seems the spark was blown out and the cylinder filled with gas hence the power drop and a/f drop.

It may have been a lil of both det/spark blow

Anyone seen detonation like this?

The A/f would go lean on a mis fire do to the extra oxygen the extra fuel means nothing oxygen sensors read the amount of oxygen only

[eades5.0]

the tuner was reading A/F from a prob in the exh, not a O2..make a diff?

[mustan5069]

the tuner was reading A/F from a prob in the exh, not a O2..make a diff?

far as i know its still a o2 sensor

[eades5.0]

Detonation then

[stevieturbo]

If it was indeed an AFR of around 9:1, that is extrememy rich, and could cause missfires.
What size plug gap are you using ?

As for seeing detonation out the exhaust....as I think you already know, thats BS.

[eades5.0]

.034 gap Autolites 3923

[mustan5069]

Detonation then

you should also be able to tell by looking at the plugs to see if it was detonating. if it was you should be able to see little specs or nicks on the plug it self

[eades5.0]

Thx..more to come

[RSNovi]

What injectors are you using?

[eades5.0]

60s

[RSNovi]

Were you able to see the duty cycle on the injectors? I wonder if you are on the edge with your injectors and they can't close fast enough and reopen so they are just static.