To keep a long story short, I decided to check the amount of vacuum my engine was pulling last week. Nothing is wrong with my car, I'm just trying to keep up with routine maintenance and whatnot (technical term 
). After driving the car around for a while and letting everything get up to normal operating temp., I connected my vacuum gauge up (I used the THERMAC vacuum port on the TBI unit), started the car, and noted the reading. The needle on the guage was very rapidly fluddering between 20 and 21 in. Hg. I just have 2 questions regarding this reading.
1.) Is a 1 in. Hg. fluctuation of vacuum at idle a bad thing or is that normal? (I know that a large variance of 15-20 in. Hg. is generally a timing or valvetrain issue, but I am unclear about just 1 in. Hg.)
2.) Does it matter exactly where you take vacuum readings on an engine? I once knew the difference between port and manifold vacuum, but I can't remember right now.
). After driving the car around for a while and letting everything get up to normal operating temp., I connected my vacuum gauge up (I used the THERMAC vacuum port on the TBI unit), started the car, and noted the reading. The needle on the guage was very rapidly fluddering between 20 and 21 in. Hg. I just have 2 questions regarding this reading.1.) Is a 1 in. Hg. fluctuation of vacuum at idle a bad thing or is that normal? (I know that a large variance of 15-20 in. Hg. is generally a timing or valvetrain issue, but I am unclear about just 1 in. Hg.)
2.) Does it matter exactly where you take vacuum readings on an engine? I once knew the difference between port and manifold vacuum, but I can't remember right now.
Comment