just out of curiousity I took a vac readong of my car today and it said about 15 at idle

is this normal low or what?

 

turbo or non turbo?

it's ok... either the engine is a bit tired or you might have a small vac leak. mines around 15 with 100k miles on it.

 

I get between 18-14............depending on the day......

 

So....just wondering....what is good? Higher vac, or lower vac?

 

higher, around 16-18 at idle is good, any lower and it's either a vacuum leak or engine going bad.. make sure your boost gauge line is tight if you're using one

 

I read about -18 on my engine @ 750 RPM idle. Of course, mine is an NA block. Normal readings for a TII are between 15 and 18. Lower than 15 may indicate problems (as already mentioned).

 

For turbo...

16 - 18, stock port
12 - 16, street port
10 - 12, bridge port
8 and under, peripheral port

This is assuming NO leaks in the intake tract.


-Ted

 

it is an 87 sport with 181k miles on it

compression is around 105 for the front
95-100 for the rear

not sure if I have an intake leak or not right now
I know the idle is a little rough some times but seems to settle down into a smooth idle after I get on it a little bit



and is it normal for the vac reading to hit about 2 when I go WOT

I never though I would come that close to hitting 0

 

Yes, WOT should push vacuum readings to "0".

The numbers I gave were for idle vacuum.


-Ted

 

ok

well motor is going soon anywhoo just curious about it

 

I can vouch for the street port. A ported rotary will give you a lot lower vacuum reading. I have a very large street port and typically see about 12 maybe 13. And my engine has perfect compression, 3,000 miles on it.