Vacuum Guage Readings

I took mine gauge off awhile back because I just have too many gauges to begin with. I have pretty high compression ratio and the gauge help me find the right power valve.

There was a station that had bad gas and I didn't know it and all of a sudden my motor started pinging under light throttle. Not knowing it was bad gas I wrote it off as not enough fuel and started watching my vacuum gauge real close and noticed that when my vacuum went below 6 no more pinging. I also noticed my driving habits in normal acceleration the vacuum went down to 7.5 so I bought an 8.5 power valve and the pinging went away. I went ahead and backed up my theory with an LM1 meter and I was right on the money.

They are cheap and great tools.