<VV> Sound of Marbles when Cold

[Mikeamauro at aol.com]

Experiencing a problem with the 67 coupe. To set up the problem, here are  
the pertinent facts about the vehicle: 110 PG; heads modified to .032  quench & 
9.5:1 compression (run 93 octane with shrouds off, in FL, this time  of year); 
has Safeguard and dual, wide band O2 sensors...both the Safeguard and  O2 
sensors have remote, cockpit display. PROBLEM: when starting off cold, after  a 
night of sitting, and when getting into the throttle about 1/2 way, a  sound 
approximating marbles cracking together can be heard. Once the engine  wars, the 
noise goes away and generally stays away all day. Cannot determine if  the 
noise in coming from the engine or if from the drive train. The Safeguard  
display, when "marbling" is occurring, remains completely "quiet" (the  Safeguard 
IS functional, however, as with the A/C on, and engine fully  warmed up on a 
hot day (yes, we get hot days in FL this time of year), the  display indicates a 
bit of activity.) Also, for quite some time, even before the  marble sounds 
started, the driver side O2 sensor has shown a propensity to  jump around quite 
a bit more than the right side (indicating possible air  introduction into 
the exhaust on left side). All exhaust packing are perfect and  tight, and 
exhaust tubes and manifolds seem a-OK. Have noticed, on the  left side of engine, 
when viewed from underneath (remember, shrouds are off), a  dark, tarry 
substance can be seen in the area where the head and cylinder  meet (the right side 
is perfect, and shows no oil or tarry substance  whatsoever). When idling, and 
listening from underneath, absolutely NO  compression leakage sounds can be 
heard, and leak down testing has shown no  anomalies. At any rate, I'm going to 
pull the left side head to go after the  tarry seepage, but I'm not confident 
resealing and re-gasketing the head  will quiet the marbles. Can a governor 
make the noise described?  other  Ideas?
Thanks,
Mike Mauro        

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