Bob,
Yes, spray it into the oil fill hole in the valve cover. Make sure the pcv valve is out and the hose plugged, and if you have a brather on the other side, take it out and plug it too.
You can try spraying aound the outside, but usually if it is the intake causing the smoke, it is leaking from the underside and pulling in oil that is splashing around from the lifters etc.
Some of the carb ports do not go directly to manifold vacuum, so it is possible that you will get a different reading there.
By the way, has the motor smoked from the start, or has it just started recently ?
E-mail me if you wish, I check it much more often.
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Bill Koustenis
Advanced Automotive Machine
Waldorf Md
1971 Heavy Chevy - original owner
team Chevelle #100
[This message has been edited by BillK (edited 06-12-99).]