What is spark knock?

[fullauto60]

I have more of a ticking comming from 360 under my hood. I dont think it's a lifter. Could even be an exaust leak.
When i step on the gas is when it gets louder but once i'm at cruising speed it lessens or mostly goes away.
Now i catch wind of somthing called spark knock and it throws a wrench in my trouble shooting.
could someone explain what it is, and why it happens. and where to get parts if it is?
i know that is alot but i'm still on an up slope on my learning curve.
Rich

[Chevelleguy]

Spark Knock is another name for detonation or pre-ignition. It is your fuel/air mixture igniting too early caused by too high ignition timing, too high cylinder temp, or too lean fuel/air mixture. Check your ignition timing first.

[mtn goat]

It sounds like you are experiencing an exhaust leak as spark knock sound like a bunch of marbles ratteling around in a tin can.

[fullauto60]

It does not sound like marbles.
It does sound like an exaust leak.
I was just curios about spark knock.
Thanks for the input so far.

[J20]

I just had the same problem with my J20 lack of power pinging I went through everything over and over again then I through some premium fuel in it and it went away the the lower octane burns at a lower temp, thus giving you preign. Try that see if it helps

[Chevelleguy]

Originally posted by J20:
I just had the same problem with my J20 lack of power pinging I went through everything over and over again then I through some premium fuel in it and it went away the the lower octane burns at a lower temp, thus giving you preign. Try that see if it helpsActually, lower octane fuel burns faster not sooner.

[Brin M.]

Spark knock or Pinging is two flame fronts slamming into each other. Knock or more properly "pre-ignition" occurs when some point in the cylinder head area (like a sharp edge) gets hot enough to ignite the atomized fuel mixture before the spark plug does creating an explosion, the edge of which is called a flame front. Then when the spark plug fires the burning fuel it sends it's own flame front spreading out. Then the leading edges of the two explosions slam into each other at supersonic speeds. YES THAT'S RIGHT! Exhaust gases are supersonic, that's why they're loud! When the two flame front smack together, ping! Higher octane gas is essentially LESS explosive gasoline, thereby requiring a stronger spark to ignite and less likelihood of accidental ignition by a hot spot. Hope that helps.

[ March 14, 2004, 08:30 PM: Message edited by: Brin M. ]

[1BDWAGN]

Check passenger side exhaust manifold. Mine had a small crack on the raised ridge on that side that faces the engine. Also I had a small exhaust leak around the shaft for the heat rise valve. What an annoying sound.

[skid2964]

If it is ping, be sure and fix the problem. ping is extremely damaging to an engine. the flame fronts colliding causes severe pressure, like hitting the piston with a hammer. It can exagerrate other problems too. (exsessive heat, etc.)

But what you describe does sound like a well placed exhaust leak.