418 Shortblock. Pistons hitting head?
06-14-2010, 09:07 PM
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418 Shortblock. Pistons hitting head? Had a head lift this weekend.. When I pulled the head it had the FWD> imprinted in the head (every cylinder) ? These same markings (FWD>) are on the pistons?
The Driver side head had no markings?
I bought this shortblock, head gaskets from a supporting vendor..
Any suggestions on what could of happened?
The Driver side head had no markings?
I bought this shortblock, head gaskets from a supporting vendor..
Any suggestions on what could of happened?
06-14-2010, 09:16 PM
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is the FWD marking raised on the piston???
It's kind of hard to believe you wouldn't hear the knocking sound if that was what was happening......of course I'm not an engine builder by any means
It's kind of hard to believe you wouldn't hear the knocking sound if that was what was happening......of course I'm not an engine builder by any means
06-14-2010, 10:22 PM
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Yes, Im just throwing this out to see if anybody else has seen this before...
Im assuming the pistons pushed the head up,and gasket let go..
The letters FWD and an arrow are laser etched in each piston..
They have imprinted FWD into the passenger side head.. Nothing on the driver side head..
Im assuming the pistons pushed the head up,and gasket let go..
The letters FWD and an arrow are laser etched in each piston..
They have imprinted FWD into the passenger side head.. Nothing on the driver side head..
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06-14-2010, 11:05 PM
#9
how much were the pistons sticking out of the block? Did the chamber match the cylinder diameter? I'm guessing the heads were slightly smaller than the cylinder wall diameter and you had thin head gaskets. Which heads are those?
The opposite of this is having heads with huge chambers and valves hitting
the cylinder wall.
Sorry for your loss. Post up your results. This is interesting to look at.
Like the other guy said, i've had motors burn holes like that when using nitrous.
Usually just melting plugs away, but often scarring internal stuff.
The opposite of this is having heads with huge chambers and valves hitting
the cylinder wall.
Sorry for your loss. Post up your results. This is interesting to look at.
Like the other guy said, i've had motors burn holes like that when using nitrous.
Usually just melting plugs away, but often scarring internal stuff.
06-14-2010, 11:13 PM
#10
Are those the head gaskets the vendor recommended?
Honestly, I've seen the pistons hit the heads a lot worse and not cause gasket failures. Then again, they probably weren't run as long since the problem was much more obvious. I'd try to take a measurement and see how far the pistons are out of the hole on both sides and see how much quench distance you had when the engine went together.
If the vendor just built the shortblock, you may be SOL, unless you can prove they recommended those gaskets. Even then, it's gonna be a longshot.
Honestly, I've seen the pistons hit the heads a lot worse and not cause gasket failures. Then again, they probably weren't run as long since the problem was much more obvious. I'd try to take a measurement and see how far the pistons are out of the hole on both sides and see how much quench distance you had when the engine went together.
If the vendor just built the shortblock, you may be SOL, unless you can prove they recommended those gaskets. Even then, it's gonna be a longshot.
06-19-2010, 07:45 AM
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The pistons are running to close to the head. You can run a slightly thicker head gasket to correct this if something is available. The piston skirt might be collapsed on the cylinder that hit the worst, it lets the piston rock more causing the hitting. Thrust is causing the pistons to hit on one side, the other side is leading with the other side of the piston so nothing touches. Check the pistons for hitting the cylinder above the top ring, this lets you know if the skirts are collapsed or the bore clearance is a touch high. Normally you will see some contact above the ring in a high power engine, but no contact is desired.
Kurt
Kurt
