two thoughts ..
I'm not sure that's the best place to access engine vacuum for your gauge ..
also ..
I have never not found 2.1 exhaust valves to not be slightly burnt when
taking the heads off for head gasket etc.

On 10/26/2014 1:58 PM, Michael Magnani wrote:
> Hi all,
> I just completed an installation of a voltmeter, oil pressure, oil temperature and a vacuum gauge in my stock, 1990, 2.1 WBX with 105,000 miles. No leaks, no smoke. Everything nice and as it should be - except for the vacuum gauge. At idle, instead of reading the expected 20 In. Hg, it reads about 13. When I rev it up and then let go of the throttle, the needle will get to 20, but then go down into the 13-15 In. Hg. range.  I've got the 1/8" vacuum tube Teed into the hose between the Air Plenum and the Fuel Pressure Regulator. I've tried two different vacuum gauges to verify that the dashboard gauge is reading properly.
> I've verified the ignition timing at 35 degrees BTDC @ 3000 RPM with the temp sensors connected. The engine runs perfectly and makes as much power as it ever did. I'm confused. Can anyone offer any help?
> Thanks,
> Mike M
>
> Sent from my iPad