I did a vacuum test on my newly rebuilt 1964 Chevy 327 V8. It has a Holley 1850-C 4 barrel on an Edelbrock Performer intake. The cam is a “.218/.218. At 750 RPM idle I get a steady 10” of vacuum. I’m at 7300 feet in altitude and I’ve read that I lose 1” of vacuum per 1000 feet of altitude. So adding back in 7” puts me in the middle of the good range. Or does it? I’m doing some trouble shooting for a backfire through the intake and I am trying to be systematic about it. Any thoughts or questions?
Thank you,
Larry
