[Philcol]

I know this is old stuff but thought I would shed some light on the subject for the newbies that had not tried this before. Below is a pic that explains what can happen if you do not pour all of the aluminum at one time. This chunk let go in number five cylinder and bent the valve sticking it open. The good news is the car was idiling when this happened and the valve just litely kissed the top of the piston doing no harm. I heard it when it dropped the cylinder and shut it off.
Now for the rest of the story. This piece had been loose under the valve for some time. I had been previously smelling and odor coming from the car everytime it was driven long enough for it to completely reach operating temperature. It would go away when the motor was shut off. It smelled like burnt wiring but we could never track down where the odor came from. I had a slight exhaust leak at the manifold and you guessed it. It was right above number five cylinder. The aluminum would get hot rubbing against the valve and actually start to melt somewhat creating the mysterious odor.

[LeighP]

Wow, considering what might have happened, you didn't come out too badly....I'd hate to see what would have been the result of the same thing at 5500 rpm instead of idle.
I've had a local PY member point me at a foundry that poured his heads....going to get a couple of sets done at the same time. Warm the heads and one complete pour, his came out fine doing that.

[lust4speed]

I wonder what kept it from being blown out the exhaust port? Seems that the rush of the exhaust gas would have it sitting down at the muffler pretty quickly.

[Philcol]

The chunk was just too big to get under the valve or it would have been very bad. This motor had been buzzed to 7 grand just to be sure it would stay together. Hate to think what would have happened if it had stuck then.

Phil