a recent trip i had pinging(clatter) of idle,after putting in some 93 octane fuel it went away,but then discovered a milky residue on the dipstick,checked valve cover oil camp,pvc valve no milky residue,the car smokes but not smell sweet?not seeing anything in radiator,but coolant level in overflow tank continues to show up low,even after adding/driving around,the performance is the same as usual,mpg did drop alittle but with the addition of bigger stickyer tires i figured that was it,am i down to pressure testing collant system,pulling plugs,block compression,or is there another easier way to diagnose???

 

It is extremely common for these engines to develop intake gasket leaks at the ends of the gasket (front and back of the motor), which will leak water directly into the crankcase.

Try tightening the 2 front-and rear-most intake bolts on each side. If they tighten, then the gasket is almost certainly bad.

I'd start there before getting all excited about a head gasket, which very very rarely leaks water into the crankcase without also leaking fire between cylinders or otherwise failing obviously.

 

The only people I have ever known who managed to blow head gaskets with SBC were those friends of mine who ran too much nitrous. And they sorta blew the WHOLE engine at the same time

I agree with the intake leaks, especially with old age and high mileage...

 

you can test for combustion gas in the cooling system. i like to do that and compression test, that way i have 2 seperate indications of problems.