Distributor vacuum lines

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JDNightFox
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Distributor vacuum lines

Post by JDNightFox »

Okay so I went through the vacuum diagrams in the repair manual and the only thing I have an issue with currently is the high altitude compensation system. I can't seem to find the HAC valve on my engine.

After tracing the vacuum lines, there are two that go behind the engine to the distributor. However, the distributor has 3 ports on it and I don't remember seeing any other vacuum systems use that port.

One of the lines going behind the engine is plugged off, and two of the distributor ports connect to each other. The third one has no vacuum when the engine is running so now I don't know where these are supposed to go.
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Petros
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Re: Distributor vacuum lines

Post by Petros »

some models did not have the HAC system, and the vac lines were capped off. my '84 does not, but my '86 had one. Might be state spacific if you go one or not. It will run fine without it, just make sure the vac lines are routed properly for the Non-HAC system.
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JDNightFox
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Re: Distributor vacuum lines

Post by JDNightFox »

Petros wrote: Fri Oct 19, 2018 9:36 pm some models did not have the HAC system, and the vac lines were capped off. my '84 does not, but my '86 had one. Might be state spacific if you go one or not. It will run fine without it, just make sure the vac lines are routed properly for the Non-HAC system.
Well it has a screw plugged in it so I’m assuming the factory didn’t do that

Also there are a few vacuum things that I haven’t found in the diagrams

so in my current setup, out of the two lines going behind the engine to the distributor, the top one is connected to the very bottom of the distributor, the two side ports are connected to each other, and the bottom line that goes around the back of the engine is plugged with a screw

To check the timing we’re supposed to unplug and cap one of the side ports on the distributor and I don’t think that will do anything if they’re connected to each other
JDNightFox
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Re: Distributor vacuum lines

Post by JDNightFox »

Okay so far I found 2 vacuum leaks when going over the lines again.

New problem: the vacuum line going to the AAP is collapsed and sealed, I pulled the line off and it's full of fuel. When hooking up vacuum to the AAP the line pulls fuel. I'm assuming it shouldn't be doing that

For reference - this is the vacuum line on the bottom left of the TVSV - connects from the AAP to the TVSV
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rer233
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Re: Distributor vacuum lines

Post by rer233 »

AAP diaph is bad.
if it aint there, there's a good chance it won't break!
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JDNightFox
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Re: Distributor vacuum lines

Post by JDNightFox »

I capped off the AAP so that won't be an issue anymore

The distributor vacuum lines have a tiny bit of vacuum on them, but certainly not the amount that the service manual says would advance the timing from 5-13 when the line is attached (the timing doesn't look like it changes at all when the line is on vs off)

I think all my lines are hooked up correctly but I'm not sure what else to look at now
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Petros
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Re: Distributor vacuum lines

Post by Petros »

see if you vac advance diaphragm is good. if it has a leak you can also cap it off until you can find a replacement. the vac advance only affects part throttle spark timing, it advances it to improve economy slightly, but if it is leaking, it only acts like a vac leak.

Many cars in the past had no vac advance, it will run fine without it. I do not know how much it affects economy, not a lot, but more on long steady state driving (as in a cross country trip), not so much in city driving.
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ccmt
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Re: Distributor vacuum lines

Post by ccmt »

Hi All,
My ‘86 failed smog in California because The vac lines to the distributor were blocked off and the guy couldn’t advance the timing. I’m reconnecting everything but am finding the diagram a bit confusing so wanted to double check with y’all.

I’ve connected the orange nozzle from the very bottom of the distributor to the red line.
E4D7AE68-5196-4597-920B-8E2192817335.jpeg
7A89AFFA-8D10-4631-983F-673195B9EED6.jpeg
But I’m not 100% on which of the other two nozzles (green and blue) to connect to the yellow line. The car is originally a Cali car.

Thanks
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dlb
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Re: Distributor vacuum lines

Post by dlb »

First, put a hose on each distributor advance port and suck on it. If you can suck air through, the diaphragm for that port is no good and the advance unit will need to be replaced (not entirely necessary but the engine runs better and gets better fuel economy with it). Leave the lines to go to any bad ports plugged.

I don't know what the CA emissions package is like but it's probably very similar to the federal one, which there is a good scan of here: viewtopic.php?t=2810
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Re: Distributor vacuum lines

Post by xirdneh »

The High altitude port on vac adv unit is the one with pin hole.
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