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#1 |
Registered User
Join Date: Nov 2012
Location: Tacoma, WA
Posts: 133
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QJ Vacuum Lines...im stuck
So, i have a QJet '77 Cali emissions Carb..this is what the front of mine looks like.
![]() I was told that i need to hook my Dist Vac Advance to the "port to the right of the fuel filter, just above the idle screw"...well...mine doesn't have that?? I have seen pics of older/other carbs that do have a port on the front right side of the carb. I currently have my vac advance hooked up to the port just above the fuel line filter housing (how it came when i bought the truck), but it is a "Ported Vacuum" spot.. so my vac advance is getting vacuum at idle. there are three Manifold ports in the bases plate, the center one is hooked to my PCV, there is one just to the right of it (capped off, seen in the pic) and one to the left of the left side idle screw, also capped off. So two questions: why is this carb different (no port on the front right) where/how do i hook up my vacuum advance? If where i have it is right, ive read in some schematics that there might have been a inline delay valve or check valve of some sort?? Obviously when ALL the vac lines where hooked up it would have been way different.. any help is appreciated.. |
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#2 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,542
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Re: QJ Vacuum Lines...im stuck
If your vac hose to the distributor has vacuum when running it's got manifold vacuum. Not ported like you say.
And so what's the problem. If you can't find a port that's got ported vacuum you'll need to use manifold vacuum. What's the concern? How does it idle? What's your initial timing set at? |
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#3 |
Registered User
Join Date: Nov 2012
Location: Tacoma, WA
Posts: 133
|
Re: QJ Vacuum Lines...im stuck
Sorry-- New to Carbs..still learning all the right terms.
Concern.. just making sure its hooked up right Idle is better (post rebuild)...actually i think the Idle is OK, but since i just rebuilt it and am playing with the idle im just trying to get it all correct. Initial timing set: I think (based on the timing light+marks on the wheel) the idle is around 12, (with the vacuum advance line disconnected from distributor, and capped on the carb) When i hook the vac line back up it advances the timing, but i have no way of knowing the #..I do know that when i had the timing set closer to Fac Spec (8) it didn't like that, it likes a little higher around 12-14. thanks, |
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#4 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,542
|
Re: QJ Vacuum Lines...im stuck
If it runs good don't be concerned about whether it's hooked up right. Your motor will tell you. My truck likes to run just like yours. Manifold vac to dizzy. Runs like crap otherwise even though it too is supposed to be hooked to ported vacuum.
Most motors ran manifold vac to the dizzy until the emissions frenzy started, then ported vac sources where available on the carb. Originally your motor was likely set up with a manifold vacuum line to a temperature control switch on your thermostat housing. And then another line to your vac pot. No vacuum when cold but when the switch warmed up it supplied vac to your dizzy. If it runs good enjoy it. If someone questions your choice of vac source just tell them that's how your motor runs best. |
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