'72 340

I'm going to research this as well but there is nothing like real life experience so I will throw this out there for you guys thoughts.

I just bought a vacuum gauge, as vacuum seems to be a big part of tuning in the engine, so I have read.

@ a warm idle of 650 rpm I'm showing 18 Hg of vacuum. No other reading have been taken yet.

Good, Bad or Ugly

Thank you
Joe.

 

that quite of bit of vacuum, doesnt have a huge cam in it, bigger the cam the less vacuum you will get,

 

Here ya go buddy!
http://www.visn2.com/UsingVacumeGauge.html
http://www.secondchancegarage.com/public/186.cfm

 

Joe -

For a modified engine that's pretty high. Even a cam with a mild lope (overlap) can knock down your vacuum. I get about 10mm with a flicker in gear (700 rpm) and about 15mm at idle (900 rpm).

Archer

 

Wow guys, thanks for the info.
Looks like I don't have any more than a stock cam.
And the idle test I did earlier looks as if the the vacuum
is exactly what is expected form a well tuned stock motor
(15 - 22 in.) I measured 18 in. and steady as a rock.

I get her all mounted up in or below the dash tomorrow and see what she looks like traveling down the road.

Thanks again, great info!!!

Joe.

 

a steady 18 is very good

 

Anywhere between 18-22 or hg of vac is good and normal

 

Thank you all for your input.

Here is a pic of the gauge in use.