drt-rcr

In reference to my previous post about the Q-jet troubles, I want to disconnect all vacuum lines that control the emissions crap and try it that way. Which port on the carb needs connected to the vacuum advance and/or other neccesary lines plus which ones should be plugged on the carb?
Thanks,,, Matt
I don't know all the vacuum ports by name so give me the location on the carb.
Thanks again,,,, Matt

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Dirt Late Model racer and Third gen lover.
91 V-6 bird with 406 in process.

[This message has been edited by drt-rcr (edited November 28, 2000).]

jrr

In the back is a full-time manifold vacuum port you could plug into your vacuum advance. I've done that with no problem on other engines, regardless of the brand. It will want to idle fast though. Just turn the idle screw down until it idles at the right speed and you may have to tweak the mixture, but hooking the vacuum advance to manifold vacuum has always worked well for me.

wiggy'sIROC

jrr,
isn't the vacuum advance supposed to go on ported vacuum on the front passenger side of the Q-jet?

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1986 IROC "Bone Stock" (for now)

Damon

I'd agree with Wiggy. I beleive you'll like the resuts better from using a PORTED advance port. That's the one on the lower passenger side front of the carb that sticks out at a slight angle. It supplies NO vacuum until you come off idle. THis way any manifold vacuum fluctuations won't cause your engine idle to "wander." If you aren't running an EGR valve then the stock vacuum can will almost always supply TOO MUCH advance (22-26*) regardless of which port you use and you will end up setting your initial advance too far retarded to make good power at WOT. Check out the tech article on this website about tunign the HEI for performance. Even if you don't use a GM HEI the info about what a prroper performace advance curve should look like still holds true.

Note that this port I mentioned takes a LARGER diameter vacuum hose than does your vacuum canister so you will need to use an adapter to move down to smaller vacuum line before plugging into the distributor, but I think the results are worth it.

CamaroMike

Hey Damon! Large cams need as much vacuum advance at idle as possible with stock cannisters because of the large valve overlap. The increaced timing will allow the engine to idle WAY I REPEAT WAY better! I built a 350 Edelbrock RPM engine with heads, cam, intake, carb, everything and that ***** would'nt idle unless I gave her at least 20 degrees of vacuum advance on top of 14 initial at idle. Not to mention full vacuum advance during deceleration will allow increased throttle response when you mash the gas again and give you better fuel economy. Sorry man but ported vacuum is for emissions and those who want to go slow.

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84 Camaro ZZ4 with HOT cam. 1.88 60' (12.98 @ 105MPH E.T.)
Other Mods: You name it and I have probably changed it.

91 Firebird 5.0L TBI

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