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Discussion Starter · #1 ·
While adjusting my timing I noticed that my vac advance was still plugged in. I unplugged it and saw that it made no difference. The advance itself works, but I hooked up a gauge to the ports coming off of the TB and noticed that none of the 3 had any vacuum. If I revved the engine the gauge would move a little (it would dance up to 1 or 2 "Hg), but there was no consistent vacuum.

It looks like the PO may have messed with these ports (I see some sort of glue around the base), I have no idea why. Doesn't the dizzy act as a vacuum advance/pressure retard so that it retards the timing when you have boost?

Is there anywhere else I can find to plug the tubes running into the TB to? I think it would be bad to plug them into the post throttle ports. Is there any line I could safely splice these into?
 

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There are both ported and unported vacuum nipples on the throttle body.
Make sure they're connected according to the vacuum diagram on the L/F inner fender.
 

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Discussion Starter · #3 ·
Yeah, I'll double check the correct config for sure, thanks for the pointer to the diagram. But I think I checked all 3 nipples and none of them had vac pressure (I checked 2 of 3 at least). These nipples have to be pulling some vacuum, they don't suck at all when I unplug them and the gauge confirmed my suspicion. When scanning through some different parts of the manual I can't find anything that talks about this (although that doesn't mean it isn't there).
 

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Yeah, I'll double check the correct config for sure, thanks for the pointer to the diagram. But I think I checked all 3 nipples and none of them had vac pressure (I checked 2 of 3 at least). These nipples have to be pulling some vacuum, they don't suck at all when I unplug them and the gauge confirmed my suspicion. When scanning through some different parts of the manual I can't find anything that talks about this (although that doesn't mean it isn't there).
Pretty sure all the vacuum connections on the tb are "above" the throttle plate, so ported and not manifold. IIRC, there's no vacuum at the advance at idle.
 

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The dizzy capsule should be connected to the small port at the top of the throttle body. It's about 6mm diameter. Not only does this advance the timing at idle but it also retards under boost. At idle it should pull about -0.5 Bar (-15" Hg). You should be able to put a long pin through it to check it's clear. Why anyone should want to block it, I don't know. Don't attach the hose elsewhere. It would seem you could, but the nipple on top of the TB is just after the butterfly plate and gives a much better response.

If you are in doubt as to position of hoses the diagram below shows all of them. The red hose shows the position on the TB you should be connecting to.

PS - Are you sure your gauge is working?

 

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Discussion Starter · #6 · (Edited)
Okay. So I just learned what a "ported" vacuum nipple is. I didn't know about those.

My hoses are a bit different cuz my engine has the evap control system. As you can see here:



I also see that I should put a 1-way valve to the vacuum canister, didn't know about that either.

Here is a pic of what mine looks like (yes I know my vac lines are a bit disorganized right now).



So there are 3 nipples, the driver's side nipple goes to the evap system, the middle nipple goes to the dizzy, and the passenger side nipple has a cap on it (bought it that way). I'll recheck all 3 later today to find out which ones are ported and see if any are plugged. I'll post some specific data from the test drive later today or tomorrow.

I know my gauge was working, because I checked it with the pump.

As an aside, I may do some research on how to "Un-californicate" the car, IE - evap system delete.
 

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I am not familiar with the three port TB. When you are testing for vacuum are you plugging the other two. It seems likely they join inside and if two are open to atmosphere you will get little vacuum on the third. If you haven't done so, try plugging two before testing the third.
 

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On a lot of vehicles, vac advance is ported for emissions reasons so at idle you won't get a read from it.

Don't eliminate your evap system.

As Jim is fond of asking: "What problem are you trying to solve?"
 

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Discussion Starter · #10 ·
Okay, tested the 2 that aren't plugged. I had a faulty test hose. They are both ported and go to normal vacuum when I rev the engine a bit. I had a leak in the adapter when I checked it last time. Glad I know what a ported nipple is now.

Thanks alot for all the help everyone.
 
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