DETONATION

[redliner]

I am sorting out my new combo 11.5-1 sbc. I am running 35 degrees total, and it looks like I am getting very faint silver dust on my # 1 plug. I am running a Mark Whitener 1050 so it should be close with jetting.I am runnning 112 VP fuel. I went from 110 to 112 then 114 jets and still see the specks with a 10 power magnifier. I backed the timing off to 33 degrees but seems like no change. I DO drive the car back to the pits after the pass so I know that the fuel reading is off but I am concerned about the specks? I cannot get pics to show up here but maybe I can take some pictures of them and send them to someones email who would be willing to look at them? THANKS!

[Warp Speed]

When you added fuel the first time, you sped up the burn rate further. Then, when you removed timing with the added fuel, you likely arrived at the same burn rate you had initially. If indeed you are experiencing detonation.
What ignition system, crank trigger or?

[swampbuggy]

Did you apply silver colored anti seize on plugs and possibly ?????? Just throwing that out there. Mark H

[redliner]

Did you apply silver colored anti seize on plugs and possibly ?????? Just throwing that out there. Mark H
[/quot Thanks for taking time to answer! I have heard of that stuff getting on plugs and use a very small amount BUT THAT could be possible! THANKS!

[redliner]

When you added fuel the first time, you sped up the burn rate further. Then, when you removed timing with the added fuel, you likely arrived at the same burn rate you had initially. If indeed you are experiencing detonation.
What ignition system, crank trigger or?

Jay, Thanks for taking time to answer! Yes, crank trigger. Number 7 NGK plugs 11.5-1 414 sbc first gen. I ran 1st pass 35 degrees timing 100 octane aviation fuel( 110 jet front and rear ) it ran 129.18 mph trap speed in 1/4 mile drags. I bumped timing back to 33 degrees 100 octane( 110 jet ) after seeing 1 speck of shiny aluminum(?) on only # 1 plug (with 10 power magnification) mph dropped to 126.55 The next weekend I bumped timing back up to 35,put new plug in # 1, drained fuel cell, installed VP 112 fuel ( 112 jet)trapped at 7000 rpm but I did not click the motor off and drove back to pits and pulled # 1 plug to look for silver specks( 10 power magnification) and it looked like it was very lightly dusted with silver dust... (crazy i know but I will get back out and check them all for what thats worth.) I am going to have to get a couple more sets of plugs and click it off on the big end and get some good plug readings.I am 57 years young and my peepers aint what they used to be AND I am a spark plug reading novice... Your thoughts?

[Zmechanic]

Take some of the brand new plugs and check them to see if there's anything natively shiny in the insulator material.

I've accidentally swiped a plug insulator just barely against the threads coming out (obviously easiest with a projected tip). Threading the plug in and out makes metal particles in the threads, or if you have anti sieze in there, there's a bunch more metal to accidentally wipe on the nose.

[stealth]

When you added fuel the first time, you sped up the burn rate further. Then, when you removed timing with the added fuel, you likely arrived at the same burn rate you had initially. If indeed you are experiencing detonation.
What ignition system, crank trigger or?

Jay, Thanks for taking time to answer! Yes, crank trigger. Number 7 NGK plugs 11.5-1 414 sbc first gen. I ran 1st pass 35 degrees timing 100 octane aviation fuel( 110 jet front and rear ) it ran 129.18 mph trap speed in 1/4 mile drags. I bumped timing back to 33 degrees 100 octane( 110 jet ) after seeing 1 speck of shiny aluminum(?) on only # 1 plug (with 10 power magnification) mph dropped to 126.55 The next weekend I bumped timing back up to 35,put new plug in # 1, drained fuel cell, installed VP 112 fuel ( 112 jet)trapped at 7000 rpm but I did not click the motor off and drove back to pits and pulled # 1 plug to look for silver specks( 10 power magnification) and it looked like it was very lightly dusted with silver dust... (crazy i know but I will get back out and check them all for what thats worth.) I am going to have to get a couple more sets of plugs and click it off on the big end and get some good plug readings.I am 57 years young and my peepers aint what they used to be AND I am a spark plug reading novice... Your thoughts?

If msd crank trigger...did you check magnets in wheel for proper pole location? About 7 degrees of timing error if in wrong.

https://youtu.be/k0m7M-DjiDo

[Tuner]

First, detonation makes tiny black specks. if you see silver color beads the source is more likely preignition, which can occur without detonation. Preignition results in extreme heat which initially distills metallic vapor of lower temperature melting alloy from the piston before actually catastrophically melting big gobs of aluminum. Detonation can occur and make the black specks without vaporizing or melting any metal from the piston.

On the other hand, if an engine ingests an astonishingly small amount of dust you may see what looks to be detonation. The color and appearance of this type of tiny specks depends on the mineral content of the local dirt or source of the dust. The trace minerals (metals) in the silica melt and fuse into tiny beads which can imitate detonation specs. Some fabric gauze air filters (K&N type) are perfect sifters to admit just the right size bits of dust to make the imitation detonation specks.

Many new cylinder heads have significantly improved "fast burn" combustion characteristics and require much less ignition advance than earlier stuff. You need to retard timing until performance begins to drop off to find the least advance that gives the best performance. Don't be surprised if it is less than 30 degrees for some new chamber and port designs.

[n2xlr8n]

I second the anti-sieze.

I also like to make sure my fuel volume / pressure to the carb is good when a sorted combination is not performing as expected.

.02 from an amateur.

[Scotthatch]

I have a couple of thoughts

Can you post a photo of a plug so we can see?

Have tried pulling 4 degrees out and seeing how it effects your ET?

[n2xlr8n]

I have a couple of thoughts

Can you post a photo of a plug so we can see?

Have tried pulling 4 degrees out and seeing how it effects your ET?

He stated " I ran 1st pass 35 degrees timing 100 octane aviation fuel( 110 jet front and rear ) it ran 129.18 mph trap speed in 1/4 mile drags. I bumped timing back to 33 degrees 100 octane( 110 jet ) after seeing 1 speck of shiny aluminum(?) on only # 1 plug (with 10 power magnification) mph dropped to 126.55"

That sort of (not always) shoots my fuel volume question in the foot.

[Scotthatch]

I have a couple of thoughts

Can you post a photo of a plug so we can see?

Have tried pulling 4 degrees out and seeing how it effects your ET?

He stated " I ran 1st pass 35 degrees timing 100 octane aviation fuel( 110 jet front and rear ) it ran 129.18 mph trap speed in 1/4 mile drags. I bumped timing back to 33 degrees 100 octane( 110 jet ) after seeing 1 speck of shiny aluminum(?) on only # 1 plug (with 10 power magnification) mph dropped to 126.55"

That sort of (not always) shoots my fuel volume question in the foot.

It also says timing is about right .... I am assuming the timing is fixed ?

[NormS]

#7 NGK plugs may be a bit too warm. I suggest using a #9 NGK plug.

[redliner]

Take some of the brand new plugs and check them to see if there's anything natively shiny in the insulator material.

I've accidentally swiped a plug insulator just barely against the threads coming out (obviously easiest with a projected tip). Threading the plug in and out makes metal particles in the threads, or if you have anti sieze in there, there's a bunch more metal to accidentally wipe on the nose.

Thanks CAN DO!!!

[redliner]

When you added fuel the first time, you sped up the burn rate further. Then, when you removed timing with the added fuel, you likely arrived at the same burn rate you had initially. If indeed you are experiencing detonation.
What ignition system, crank trigger or?

Jay, Thanks for taking time to answer! Yes, crank trigger. Number 7 NGK plugs 11.5-1 414 sbc first gen. I ran 1st pass 35 degrees timing 100 octane aviation fuel( 110 jet front and rear ) it ran 129.18 mph trap speed in 1/4 mile drags. I bumped timing back to 33 degrees 100 octane( 110 jet ) after seeing 1 speck of shiny aluminum(?) on only # 1 plug (with 10 power magnification) mph dropped to 126.55 The next weekend I bumped timing back up to 35,put new plug in # 1, drained fuel cell, installed VP 112 fuel ( 112 jet)trapped at 7000 rpm but I did not click the motor off and drove back to pits and pulled # 1 plug to look for silver specks( 10 power magnification) and it looked like it was very lightly dusted with silver dust... (crazy i know but I will get back out and check them all for what thats worth.) I am going to have to get a couple more sets of plugs and click it off on the big end and get some good plug readings.I am 57 years young and my peepers aint what they used to be AND I am a spark plug reading novice... Your thoughts?

If msd crank trigger...did you check magnets in wheel for proper pole location? About 7 degrees of timing error if in wrong.

https://youtu.be/k0m7M-DjiDo

NO I WILL THO!! THANKS!!!