68 Vacuum Tank Pressure Question

[Jeffrey A.]

My 68 is a 427/390 a/c coupe. I am currently getting ready to test my vacuum tank and system . I first want to her my tank it vacuum. Does anyone no what type of vacuum should I making and holding in my vacuum tank. I am going to put a gauge on the tank to check it.

[Michael W.]

Re: 68 Vacuum Tank Pressure Question

Should be pretty close or equal to manifold vacuum.

[Jeffrey A.]

Re: 68 Vacuum Tank Pressure Question

Thanks Mike, I am holding 12 pounds of vacuum.

[Terry M.]

Re: 68 Vacuum Tank Pressure Question

Thanks Mike, I am holding 12 pounds of vacuum.

I am trying real hard here not to be a wise a$$, and I am failing

Pressure is measured in pounds per square inch in the USA

Vacuum is measured in inches of mercury in the USA.

If you are holding 12 pounds you are most likely in the gymnasium. I would think it is pretty hard to hold 12 pounds of vacuum, but I can't say I have ever tried.

[Jeffrey A.]

Re: 68 Vacuum Tank Pressure Question

Typo on my part I meant Inch pounds, thanks for the correct. I was just wondering what type of vacuum should I have to run the system. I am going through the system now to find out if a leak in a hose or a fitting.

[Terry M.]

Re: 68 Vacuum Tank Pressure Question

Engine vacuum can be anywhere from 12 to 18 inches -- depending on the engine state of tune and speed. On coast-down on a hill the vacuum could perhaps get to 20 inches, but not too often. I don't know what you are using for a vacuum pump, but anything that sucks more than 25 inches is overkill.

[Jeffrey A.]

Re: 68 Vacuum Tank Pressure Question

Thanks Terry. Got my system working today. Thanks again for the help.