1st design off road cam #3927140 Vacuum Issue?

[1967Z28]

I ran that cam in my 302 for a number of years and loved it. Never had a detonation problem using pump gas premium but it did tend to foul plugs. I drove this car as a daily driver and would change plugs about every 1000-2000 miles. No vacuum problems at all. My engine was stock other than headers and the cam, and I was running 4.10 gears. I think 4.10 gears were great with that engine. Best to run 302s with a 4-series gear. I don't think you should run the 140 cam without headers. Chevrolet certainly did not recommend it back in the day. Is that what you are considering?

-Jon