I'm curious about the tube that runs from the upper intake neck to the lower intake. How does it tie into the runners, just one or all of them ? The reason I'm asking is I have a trueleo intake and had it plugged, well the plug rotted and created a big leak but it ran alot better at WOT. Almost broke the slicks(drag radials) loose when it hit 2nd gear.

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85 GT 3.4
14.9 @ 90 1.9 60' Old TH125/3.06
Unknown New 4T60/3.42

Vacuum leaks aren't as big of a deal at high RPM... if a big vacuum leak gave you more power up top, fix your tune...

I am pretty sure it is just a hole drilled all the way down the center of the lower intake to provide IAC air... I don't think they'd leave the cylinders unbalanced.

are you asking about the EGR TUBE ? or a rubber line ?

That's the idle air tube. There's supposed to be an L shaped tube from the back of the TB to the fitting on the lower intake.
The fitting just opens into the front of the lower intake, IIRC.

The idle air passage in the lower intake branches out to each intake port. The cold-start injector also squirts fuel through those same passages.

edit to add: If you get better WOT performance with a vacuum leak, then your tune is probably too rich at WOT.

[This message has been edited by Blacktree (edited 11-08-2013).]

It's the rubber tube. The AIT and TPS were both bad also, so there's one rich problem. This is with a GN 59mm TB, guess it could still use more air.

quote Originally posted by Blacktree: The idle air passage in the lower intake branches out to each intake port. The cold-start injector also squirts fuel through those same passages. ...

Thanks. Been a long time since I looked at a stock lower.

Does everybody have me on 'ignore' or something?

That small line goes to fuel reg under the plenum. Send me an e-mail and Ill send you vacuum line layout drawing. rspiderii@aol.com

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RSpiderII@aol.com