now THATS a cracked piston

[Anonymous]

nice huh? This is fromlast year when I had to have the rebuild....

what would cause something like this? Chaz

 

[addo]

Bore wear and detonation, I reckon.

 

[xzerokidx]

I had the #3 piston cracked the whole way across the top of the piston in my 200

 

[rbohm]

8) the damage in your pic is usually caused by detonation, and pretty severe at that.

 

[Anonymous]

not to be stupid...but what is detonation? is that being way out on advance?

because when I got the car back...it was way out. I fixed it. I still have to figure out the adjustable vaccuum advance

 

[rbohm]

8) what happens in a normal burn is, you get a smooth flame front from one end of the chamber to the other. when you get detonation, you actually have two, or more, flame fronts that collide with very high force. the result is excessive pressure on one small area of the piston, usually towards the center, or on your case one edge. what you hear is the flame fronts colliding, the sound of rocks being rattled around in a tin can. detonation has a few components that need to work together;
1: a lean mixture
2: excessive spark advance
3: a hot spot in the combustion chamber
4: high engine load
5: poor fuel quality
6: high compression or boost pressure

any combination of the above items will result in detonation. there are a couple of other things but i dont remember what they are off hand.

 

[Anonymous]

i have an idea my timing was way out ...but I dont think I am too lean as I am using 1 tank of gas every 175 miles with no leaks. I think I have too much gas going in.

could a worn fuel pump provide TOO MUCH gasd? I should really change that

another question...return fuel line...where is it?

 

[Anonymous]

There is no return fuel line .

 

[Anonymous]

i thought I saw someone mention that

my bad

so could a worn fuel pump pump TOO MUCH fuel?

 

[Anonymous]

Unlikely that a pump would push more fuel as it wears. I suspect you were running around with too much advance for too long. Sometimes it isn't that easy to hear and recognize.

 

[Anonymous]

retarding advance is counter-clockwise or clockwise?


maybe I need to just go have it tuned somewhere...reputable

 

[rbohm]

8) retarding timing on these sixes is clockwise as that is the way the dist shaft turns.