Ignition; Determining Ping/Knock/Detonation

[Mopar-Charger]

I've been tuning my system and I have it running very well right now. Car hates the restrivtive 2 inch tailpiped exhuast, but if I run cutouts it runs like a champ. What I can't figure out is;

What a ping/detonation because of timing sounds like?

My Probillet dist is all in a 2000 RPMS, I'm doing 12 initial and 35 Total. At about 1800 RPMS there s a little stutter, but leading upto/past that it cruises and WOT's very well. Is this a timing problem? I think I can swap springs to put full timing at 3000? Is that too late? My stall is done at 1800-2000 RPMS.

Thanks

 

[Garys1969RR]

I would describe it as a rattling sound coming from the engine, usually when under heavy load, wide open throttle conditions. It immediately stops when you let off the gas pedal, or even back to half throttle. Then will start again when you floor it. Detonation is when the mixture explodes spontaneously before the spark plug fires. Either condition will damage engine components if it continues for awhile.

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It can be caused from too high a compression ratio for the octane of the fuel being used. Also too much advance on the ignition timing can cause it. Too lean of a fuel/air mixture can make things worse. Overheating of the engine can also cause it to move toward ping/detonation.

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A diesel engine always pings/detonates. Thats the rattling sound you listen for, but a diesel is usually louder.

 

[440roadrunner]

You have to be awful careful. Generally, with today's alky gas, lower compression, and longer duration cams, knock can be hard to hear. You can break rings / ring lands before you "really" hear it. "Back when" factory engines were 10X : 1 there was NO question. You threw in part of a tank of "reglar" by mistake, you HEARD the ping

Google around. "Some of the guys" on the internet have been playing with adding knock sensors simply to listen to. Some of them can drive a pair of headphones directly.

Learn to read plugs. Degree your balancer. Determine and KNOW where your timing is at. Get your self a performance meter like a G-tech /pro (accelerometer) and O2 wideband setup.

 

[moper]

There are two types of uncontrolled combustion: Preignition (or "ping") and detonation. Both are hard on the engine and reduce power. Ping you will always be able to hear. Detonation many times is not audible. Mopars have issues with both, and if they have stock big open chamber heads, they will be more inclined to be affected with either or both. Ping is a high-pithed rattle and results from the fuel and air mix igniting earlier for some reason other than the spark plug. It's similar to the sound of having a bolt loose with a washer that vibrates or a bag of marbles that is shaken. It also is self-propogating. Once it starts, it won't stop until the situation in the chamber changes... Normally that means letting off the throttle. Detonation is a second ignition point where the two combustion events impact each other and the result is like a hammer blow on the piston. It can break blocks, shatter pistons, crack rings, take the crush out of bearings, blow gaskets, break rods and cranks... It's the worse of the two. If you hear it it's a lower pitch than pinging and can come and go as the rpms rise. It can also be silent, but you'll see signs of it during a teardown and you can see it on the dyno with the right monitoring.

As far as your car... IMO the timing comes in too fast. I like initial of 15-18 degrees, with total around 38-40. I like it a litle slower -all in by 2800-3K. Too early and it can ping. If you have a bog or studder it may be carb related. Always set timing first as timing will affect the carb tuning. Carb tuning will not affect timing.

 

[Mopar-Charger]

There are two types of uncontrolled combustion: Preignition (or "ping") and detonation. Both are hard on the engine and reduce power. Ping you will always be able to hear. Detonation many times is not audible. Mopars have issues with both, and if they have stock big open chamber heads, they will be more inclined to be affected with either or both. Ping is a high-pithed rattle and results from the fuel and air mix igniting earlier for some reason other than the spark plug. It's similar to the sound of having a bolt loose with a washer that vibrates or a bag of marbles that is shaken. It also is self-propogating. Once it starts, it won't stop until the situation in the chamber changes... Normally that means letting off the throttle. Detonation is a second ignition point where the two combustion events impact each other and the result is like a hammer blow on the piston. It can break blocks, shatter pistons, crack rings, take the crush out of bearings, blow gaskets, break rods and cranks... It's the worse of the two. If you hear it it's a lower pitch than pinging and can come and go as the rpms rise. It can also be silent, but you'll see signs of it during a teardown and you can see it on the dyno with the right monitoring.

As far as your car... IMO the timing comes in too fast. I like initial of 15-18 degrees, with total around 38-40. I like it a litle slower -all in by 2800-3K. Too early and it can ping. If you have a bog or studder it may be carb related. Always set timing first as timing will affect the carb tuning. Carb tuning will not affect timing.

Thanks for the info, I always try to be a little more conservative on the timing. Less than what can do major harm to the engine. ai'm going to swap a light silver spring out for a blue spring, should give me all in at 2800. I'll drive and see if there is a difference.

Thanks,

Jake

 

[383man]

Dont know if I mised it or what but what eng are you running and is it aluminum or iron heads ? Much of detonation can be stopped by the way the eng is built also. Basically detonation is when more then one flame front starts and they collide with each other like a hammer hitting the piston as was told by "Moper" who gave a good account about it. On my eng build I use aluminum closed chamber heads and built .046 quench in my eng. Also the cam plays a big factor like in the intake valve closing as it has alot of control over how much cyl pressure the eng builds which the cyl pressure is a big factor in the detonation. I also use a cam that helps keep my cyl pressure where it should be to run 92 pump. I run about 24 initial timing and 37 total all in by 1800 rpm and I have no ping or detonation knock at all and alot of the reason is how I built the eng. But if we know what eng it is we may be able to give some more info that may help you. Ron

 

[Mopar-Charger]

Dont know if I mised it or what but what eng are you running and is it aluminum or iron heads ? Much of detonation can be stopped by the way the eng is built also. Basically detonation is when more then one flame front starts and they collide with each other like a hammer hitting the piston as was told by "Moper" who gave a good account about it. On my eng build I use aluminum closed chamber heads and built .046 quench in my eng. Also the cam plays a big factor like in the intake valve closing as it has alot of control over how much cyl pressure the eng builds which the cyl pressure is a big factor in the detonation. I also use a cam that helps keep my cyl pressure where it should be to run 92 pump. I run about 24 initial timing and 37 total all in by 1800 rpm and I have no ping or detonation knock at all and alot of the reason is how I built the eng. But if we know what eng it is we may be able to give some more info that may help you. Ron

It's a built 360

2.02 heads
Big Cam
Performer RPM intake
MSD ignition


I had a crap ignition before, I had to run atleast 15-17 initial to keep it running.

Now with the MSD It runs best at abotu 12-13 with a total of 37-38

Only problem i come about is when starting the car it "Ticks" until the oil gets going and then it smooths out? I run 10w 40 oil. I will check it once it cools off, but do i need to go thicker? Winters are 30 degrees at the lowest, summer is 110 degrees highest.

Thanks

 

[Bigal75]

Is it a solid lifter cam?

 

[Mopar-Charger]

Only problem i come about is when starting the car it "Ticks" until the oil gets going and then it smooths out? I run 10w 40 oil. I will check it once it cools off, but do i need to go thicker? Winters are 30 degrees at the lowest, summer is 110 degrees highest.

Thanks,

Jake

The tick was from a mis-adjusted choke. Choke was full on and wouldn't come off until about 200 Degrees. Car never exceeds 170. Fixed that and tick went away.

Still looking for an oil for the winter, I've heard about adding a zinc additive. Is that worth it?

Is it a solid lifter cam?

Yah

 

[Bigal75]

I run Brad Pen oil. Has all the right additives for solid cams. 10 40 is fine. I've used that oil at -30 with no issues.

 

[Kern Dog]

Alright... I am going to offer a different perspective, one that may annoy some here. No big deal though.
SOMETIMES a car can detonate occasionally with no damage to the engine whatsoever. This is not to say you should just let it happen forever, just that the knock isn't an instant destructive event that some say it is. I had troubles dealing with detonation in my 440/493 that took me a few years to finally figure out. No, I wasn't constantly working on it, this is a hobby car that sits parked in the rainy season as well as when it gets around 100 degrees. I had a condition where the car would audibly knock every time I pushed past 3/4 throttle, so I mostly drove it just shy of that. I tried several things to eliminate the knocking but the simple fact was that I either had to run 110 octane gas or lower the compression and run 91. I decided to install thicker head gaskets to lower the compression. When the heads were off, I had them ported. Even after thousands of miles of occasional detonation, there were absolutely NO signs of damage to the pistons. I even pulled the oil pan to install a 6 quart HEMI pan, and decided to pull a few connecting rod caps to inspect the bearings. Heavy detonation often results in accelerated wear on the top half of the rod bearings due to the immediate strain at TDC. Mine looked fine.
Many internet forum guys barked that thicker head gaskets wouldn't help, that I'd lose quench and make things worse. These guys slipped into the shadows when I reported that my detonation problems went away with the changes. I was able to run more spark advance which resulted in the car being faster than ever while not knocking at all.
I'm no expert, but I am smart enough to know that there are many variables to consider. There are many ways to arrive with a winning combination, so what works for some may not work for others. Trial and error can be a great teacher, though it can cost a few $$$ to experiment.