Per ignition / detonation - Need help

What a day.  Looking for advice and what direction to go.  I just installed a Holley Sniper a few months ago.  I have put maybe 100 miles on it tops since I installed it.  Last week while adjusting the iac it went extremely rich and and spewed black exhaust before quitting.  I know what caused that and have fixed that problem.    So today I figure I check my plugs and do a little tunning. The plugs did not look too bad, so I decided to use my endoscope and check out a couple of the cylinders just to see how they looked.  
Well, did I get a big surprise!  See pics. I know that the last time I checked the pistons when I got my endoscope back in August they were in good shape.   Question- is this more a pre-ignition issue or detonation and what recommendations to correct it.  The car is to loud to hear any knocking.  Also, how would you rate the damage that has been done.  Still ok to drive if I get problem fixed?   The engine seems to be running fine as is.  

Here is the engines current configuration.
460 with d0ve-c heads.
10:1 CR
Howard hydraulic roller cam -dur 282/286, Lift .600/.593,
Dual plane intake with 1/2 spacer
Holley Hyperspark distributor - current timing is 15 idle - 36 cruising - 32 wot.  No advance built in at the moment.
AFR 13.5 idle - 14 cruise - 12.5 wot.
Running autolite 45 plugs
Running 93 octane but had to put in about 1/2 of tank of 86 last week.

These are the worst two of the bunch.    Also two of the  plugs.  Thanks for any help you can provide.

What caused the IAC to go wonky (yes that’s a technical term ) Have you ran a compression check? How about a leak down check? What is the plug gap?
The piston top looks weird but the plug looks pretty good.

I had the idle spark on while trying to adjust it.  Didn't know that was a no-no (also technical term ) at the time. Turn the screw too far and idle dropped and almost stalled.  The afr reacted dumping more fuel in but it was to late and flooded and stalled.

Compression was 210 to 213 last time I ran one about 6 months ago.  Never done a leak down.  Plugs are gapped at .040.  I should also mention I have a MSD6a box and blaster coil.

Here is a picture of the worse piston above back in August before the pitting started.

If that duration is at .050" the cam is way too large for the rest of the package.
The plugs show a rich mixture where the ceramic has a thick brown glaze. I dont see aluminum flecks on the plugs that indicates detonation. If the piston tops are a rough surface I dont see an issue.

If you look at the top two pictures in the original post the piston tops are pitted where previously they weren't - see picture in previous reply. The cam is what came in the engine when I got the car. Engine was built by a professional shop. The engine has always run great and still does but from what I'm seeing my pistons are taking a hit of some kind.

Have you checked the timing recently? Have you checked TDC and compared it to the timing marks on the balancer?
I have not used a any of the Holley EFI stuff but with my mega squirt I have to turn on “base timing mode” to check and set base timing. Once base timing is set you switch back into timing controlled by the timing map. It’s similar to factory Ford stuff with a spout connector.

Yes timing is good and dead on. I have checked that twice now and have also checked the tdc mark with a piston stop. Holley has a static mode where you can set the timing and it will stay there regardless of rpm. This is used to set check timing after setting the rotor phasing. I am running a timing map but really don't have any advanced in it yet so it is acting like just mechanical timing except at wot where I have it dropping by 4 degrees.

Are you sure that is pitting or is carbon built up and flacking off. If it ran rich enough to start blowing black smoke it doesn't take long for the carbon to build up. I have had carbon built up before and busted it loose with sprinkling water down the intake while at a high idle

69F100 wrote:Are you sure that is pitting or is carbon built up and flacking off. If it ran rich enough to start blowing black smoke it doesn't take long for the carbon to build up. I have had carbon built up before and busted it loose with sprinkling water down the intake while at a high idle

Wish it was but I don't think so. The pitting in the picture doesn't show as well as the actual video on the phone.

Honestly, I don't think 93 octane is enough, I would add octane booster to every fill up because what it says at the pump, is not always what it really is.
Also, you may want to try a little colder plug.

BBFTorino wrote:Honestly, I don't think 93 octane is enough, I would add octane booster to every fill up because what it says at the pump, is not always what it really is.
Also, you may want to try a little colder plug.

I have order some colder plugs today. Going with NGK AR6FS. They are one step colder than the Autolite 45's I am using. I thought about the octane booster but I don't think my compression is high enough to warrant it. I might give it a try to see if I notice any difference. I'll try the plugs first and monitor it and then go from there.

You’re static compression may not be high enough to warrant fuel above 93 octane but what about you’re dynamic compression? You already said that you were over 200psi during a cranking test.

wickettoby1 wrote:You’re static compression may not be high enough to warrant fuel above 93 octane but what about you’re dynamic compression?  You already said that you were over 200psi during a cranking test.

I haven't run the numbers on a calculator but I would calculate around 8:1 or so.  I've been running 93 because the engine runs better with it.  It will run on 86 but you can tell a power lost and it idles rougher.

I had a 9.8.1 dove headed 466 that would run terribly on anything less than 93. I never really experimented with 92 or 91 but one time I accidentally I mixed 1/2 a tank of 87 with the 93 and knew fairly quickly that something was wrong. I confirmed the issue when I looked at my gas receipt the next day.

Update:3-19-22
I ran a compression test yesterday and all seems fine on that. 10 lbs. max difference between all cylinders.  Today I ran a leak down test and no issues found there either, so any damage done so far is minor if you want to call it that.  I took the endoscope again and used a 45-degree mirror attachment and was able to get a look at all the valves today.  I think I have two separate problems.  

Problem 1:  The exhaust valve in cylinder 5 also has pitting in the center of it (see picture).  This is directly above the pitting in the piston.   This now makes me suspect that something got into the cylinder.   After thinking about it for a while I remember that when I was replacing the valve cover gaskets that the stud came out of the upper front conner above # 5 intake port.  When I screwed it back in it stopped momentarily and then went in and seemed a little deep.  I now do believe it punched through the casting and I got a piece of the cast iron in the cylinder.  I know that this can happen with the 460 heads.  I checked out the cylinder again thoroughly and didn’t see anything laying in it so I think it's been ground up and blown out.   So, for now I’m writing that off as the cause of the pitting and will keep an eye on it.

Problem 2: I still think I might have a little pre-ignition / detonation going on based on the looks of some of the other pistons.  I think it's more preignition than detonation.  I will proceed to try to correct this by going with colder plugs and then adjusting the timing and afr as needed.  I have already ordered a set 1x colder plugs but have decided today to step down 2x. I will pick up a set on Monday. Going to go with NGK AP7RF.  I’m will then make afr and timing adjustments as needed.   I will continue to monitor everything very closely for the next several months to see if there are any changes.

Thanks to everyone for the suggestions and help.

You "may" have had a situation where the 'piece" blew around to other cylinders before it exited. I have seen this before where "innocent" cylinders were damaged by parts from blown up cylinders.

gt350hr wrote:   You "may" have had a situation where the 'piece" blew around to other cylinders before it exited. I have seen this before where "innocent" cylinders were damaged by parts from blown up cylinders.

Very good point.  Something I didn't think about.  I have a dual plane intake so it would have stayed on the left bank.  After looking at the pictures again the two that I posted pictures of are numbers 5 and 6 with 5 being the worst and then number 6 coming in second so it makes sense that I might took a hit on a couple of them.

I know you think your problem is addressed. However just for your knowledge spark plugs can not be read correctly after idle and normal driving. Fresh plugs, WOT pull and shut off the ignition then coast to a stop and check the plugs. The strap will tell you the timing and the porcelain will be AFR. Google is your friend here for more details, but timing mark should be in the bend of the strap and the fire ring on the porcelain should be about 1/8” from the bottom. I use a hole saw to cut the plug and pull it apart to read the afr.

Hope this helps.
Nick

Stangn wrote:I know you think your problem is addressed. However just for your knowledge spark plugs can not be read correctly after idle and normal driving. Fresh plugs, WOT pull and shut off the ignition then coast to a stop and check the plugs. The strap will tell you the timing and the porcelain will be AFR. Google is your friend here for more details, but timing mark should be in the bend of the strap and the fire ring on the porcelain should be about 1/8” from the bottom. I use a hole saw to cut the plug and pull it apart to read the afr.

Hope this helps.
Nick

I appreciate the info. It's something I'm aware of but unfortunately I don't have a strip of road to be able to do that. The local track will be opening the end of April beginning of May and I can take it down there but until then I'll have to rely on the info I have on hand. When you say you use a hole saw what part of the plug are you cutting apart? If you post a picture that be great.

I take the spark plug and put it in the vise, then take my air powered cut off wheel and carefully cut the threaded part off, be careful not to touch the porcelin part, as after you cut off the threaded part at the base of the plug, you can easily see where the coloring on the porcelin is.

Back off the timing a few degrees or get better fuel?

Where are you getting your fuel? Is it consistent? Have you checked it?

Another source for a colder spark plug is an autolite 124 .Which came in big ford trucks (f600-700) with 391 engines .I have used them with great success in high compression Fe engines .That plug should work fine in yours also .Doug

[/quote]
I haven't run the numbers on a calculator but I would calculate around 8:1 or so.  I've been running 93 because the engine runs better with it.  It will run on 86 but you can tell a power lost and it idles rougher.[/quote]

The data on that engine tells me it will most likely detonate on 86 octane. If you ran it with one load of 86 in it that would tell me that it took the hit then.
Other factors are the weight of the vehicle, timing curve, and engine coolant temperature. I would try to keep the coolant below 180 and delay the timing all in until after 3,000 rpm. You may also want to look at reduce the vacuum advance curve.
Also getting upwards of 200 psi on a compression test shows that the cam is rather mild which is another warning here. Using a more aggressive cam will bleed off that pressure and hold off detonation.

manofmerc wrote:Another source for a colder spark plug is an autolite 124 .Which came in big ford trucks (f600-700) with 391 engines .I have used them with great success in high compression Fe engines .That plug should work fine in yours also .Doug

The big problem is that the 124 is a standard tip type plug vs the projection tip on the 45 and is more prone to fouling. I didn't realize at the time that I ordered the NGK's but they are standard tip also. I'm trying to stay with a resistor projection tip so I ended up going with Champions RF9YC.

Dave De wrote:

I haven't run the numbers on a calculator but I would calculate around 8:1 or so.  I've been running 93 because the engine runs better with it.  It will run on 86 but you can tell a power lost and it idles rougher.[/quote]

The data on that engine tells me it will most likely detonate on 86 octane. If you ran it with one load of 86 in it that would tell me that it took the hit then.
Other factors are the weight of the vehicle, timing curve, and engine coolant temperature. I would try to keep the coolant below 180 and delay the timing all in until after 3,000 rpm. You may also want to look at reduce the vacuum advance curve.
Also getting upwards of 200 psi on a compression test shows that the cam is rather mild which is another warning here. Using a more aggressive cam will bleed off that pressure and hold off detonation. [/quote]



I have timing set right now for all in at 3000 rpm at 34 degrees. No vacuum advance built in.  I have a 185 thermostat and the engine runs 180 to 190.  I swapped my tank out to a Aeromotive GenII and filled with fresh 93 octane.  I switched plugs to Champions RF9YC's.  I'm still playing with the afr trying to get it dialed in.  Right now I'm at 13.3 idle, 13.6 cruise and 12.5 wot.  I know the proper way to read plugs but at the moment I don't have a place where I can run wot and kill it so I'm trying to make adjustments by reading them as is.  So far the plugs are showing very little color so I will continue to try to adjust to find a sweet spot. Changes made so far from original settings are 2 degrees less timing at cruise, dropped afr from 14 to 13.6, dropped one temp setting on plugs and have made sure gas is 100% 93.