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78 SC: 3.0 CIS part name + function?
While changing my rotor+cap I removed the little hose from following part and noticed it is frail at the bottom and very easy to deattach:
 Could someone name the part + explain the function of it and explain the possible downside of this hose not seating perfectly. Thanks, Ward |
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07-14-2009, 03:15 AM
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Almost Banned Once
Join Date: Feb 2009
Location: Adelaide South Australia
Posts: 38,355
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That's the vacuum retard on the distributor.
A lot of people have them completely disconnected and the port at the other end on the air box plugged up... (including me) If you want to keep it just snip off bit and push it back on... (Just past the frail part)
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07-14-2009, 03:34 AM
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Join Date: Oct 2008
Location: Nash County, NC.
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But you cant plug and disconnect both sides. One is a retard and one to the right in the picture is additional advance for higher RPM. To make sure, at idle put your tongue against the hose and the one with vacuum is the idle retard.
You need to check the vacuum on the high RPM side at high revs. If you dont get a vacuum you have to try to clear the port on the throttle body with tip cleaners as they carbon. Bruce |
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07-14-2009, 03:45 AM
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Join Date: Oct 2008
Location: Nash County, NC.
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Sorry, I didnt see you were a 78SC, I thought it was 80-83 with the dual vacuum lines. 78 is suposed to have only one line and that is advance, not retard as the mid 70s 2.7 all were. You truly need the one to the right in picture operating for advance
Bruce |
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07-14-2009, 03:51 AM
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Sorry this was a pic I got from the web from a 1980 SC, I believe I have indeed only one line. Will check when I get home.
Can this one line be disconnected or not? |
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07-14-2009, 04:01 AM
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daily driven 911
Join Date: Feb 2009
Location: austin texas
Posts: 125
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Quote:
on this pic, the one on the right is advance?? if so is it the same on an 82?? |
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07-14-2009, 05:36 AM
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Join Date: Apr 2006
Location: Charleston, SC
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Left side is advance .... right is retard.
Since he has a 78 he should only have the advance vacuum line. Like sc_rufctr said, snip the line past frail area and hook it back up.
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82 911SC Coupe Chiffon / Chocolate 9.5 JEs, 964 Cams, SSIs, Dansk Exhaust, CIS (SOLD) |
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07-14-2009, 05:40 AM
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Join Date: Oct 2006
Location: MYR S.C.
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not to insult, but based on your question, if your car is running fine, i would not modify anything. i would replace the hoses if they are old. do them one at a time so you do not get confused as to where they go.
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86 930 94kmiles [_  _] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD88 BMW 325is 200K+ SOLD 03 BMW 330CI 220K:: [_ _] RUNNING: [__] NOT RUNNING:01 suburban 330K:: [_ _] RUNNING: [__] NOT RUNNING:RACE CAR:: sold |
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07-14-2009, 06:28 AM
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Join Date: Aug 2000
Location: Calabasas, California
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Ditto. I would also add that when I replaced hoses in my 73.5 911T, I found that what Porsche offered was noticably different and better fitting than what my local auto supply place had. Some were definitely expensive. But, in the end, I think it was worth it.
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07-14-2009, 09:22 AM
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Join Date: Apr 2006
Location: Charleston, SC
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I just realized that the picture is of my 80 engine that I rebuilt! Did you get it from my CIS pics?
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82 911SC Coupe Chiffon / Chocolate 9.5 JEs, 964 Cams, SSIs, Dansk Exhaust, CIS (SOLD) |
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07-14-2009, 10:32 AM
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Quote:
 I was just bored at work and thinking about it, that's why I used a pic I had in my archive.For the record, I will indeed replace the hose but just wanted to know the purpose of it... (And if it is indeed necessary thus not something emission related etc.) |
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07-14-2009, 12:22 PM
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Join Date: Apr 2006
Location: Charleston, SC
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Quote:
Your 78 should only have one nipple on the distributor diaphram on the left side (advance line). It is VERY much needed b/c it advances your ignition timing during throttle. The 80-83 has the retard line (right side) and the advance line. The retard was solely for emissions as I understand it. Many people pull this line and plug it - which then requires that you adjust your idle speed down b/c when you pull the retard line your idle will increase. Others have their distributor recurved and will delete both vacuum lines. Basically they rely soley on mechanical advance.
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82 911SC Coupe Chiffon / Chocolate 9.5 JEs, 964 Cams, SSIs, Dansk Exhaust, CIS (SOLD) |
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07-14-2009, 12:30 PM
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