I'm curious how much the different types of port affect vacume. Does your vacume get lower the bigger the ports become???

Is there anything else that can affect vacume besides a port, a leak, or a bad seal???

What kind of vacume are people pulling with ported engines and how ported is it (if you know)?

Thanks,
STEPHEN

 

Typical stock port - 18" to 20" of vacuum
Mild streetport - 18" to 14" of vacuum
Wild streetport - 16" to 12" of vacuum
Bridgeport - 14" to 10" of vacuum
PP - 12" to under 10" of vacuum

Bigger the port, lower the vacuum...

http://fc3s-pro.com/TECH/PORT/porting.html


-Ted

 

My street port pulls around 12 to 13" of vacume.

If you have a little hose blown off the plenum you will notice a higher than normal idle with a lower than normal vacume as well.

 

ok, I was just making sure. I've got a pretty agressive streetport that pulls around 12-13 also. Just wanted to make sure I was ok

lol

STEPHEN

 

Thats a damn big *** street port !

 

That motor properly broken in yet?&nbsp I find that the idle vacuum doesn't really start stabilizing until after 5,000 miles after a rebuild!&nbsp Maybe my rebuilds take too long to break in!



-Ted

 

I dont have quite that many miles on it yet. I probably have about 3000 on it now. Maybe after another couple thousand the vacume will increase if thats been the case. I wasnt aware of that.

Hopefully its not just your rebuild

STEPHEN

 

Can tuning affect the amt of vacume you pull???

If so how?

Thanks,
STEPHEN

 

The streetport that I did pulls about 14-16 vacuum at 1000 RPM idle speed.

 

Yes, extreme ignition timing changes can!
We found that out by accident while tuning on Haltechs.
A 13B-REW streetport was barely registering 10" of vacuum when we had the ignition timing WAY off by about 30&#176!&nbsp Getting the ignition timing back to TDC brought it back to about 14"...

We thought it was weird!


-Ted