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81 SC sputtering/small backfires

 
Old 08-03-2009, 11:49 AM
  #31  
Dave C 911sc
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I too thought it was an exhaust leak at first, but I haven't been able to find a leak...
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Old 08-03-2009, 01:11 PM
  #32  
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I do not have anything on my distributor that looks like the vacuum line attachment shown. Maybe I have an updated one that has no vacuum hoses?
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Old 08-03-2009, 02:20 PM
  #33  
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time to start posting some pics. I think your best investnment right now would be a digital cam
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Old 08-05-2009, 12:41 PM
  #34  
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Default Distributor

Here are some pictures of my distributor, as you can see there isn't any diaphragm or hose connector anywhere on it.
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Old 08-05-2009, 12:57 PM
  #35  
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This is an 81 you say ? definitely no vacum advance. can you post a couple of pics of the engine further back ?

Anyone else have an 81 with similar confiuration ?
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Old 08-05-2009, 01:52 PM
  #36  
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engine
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Old 08-05-2009, 01:54 PM
  #37  
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In 101 projects book it talks about upgrading to a bosch distributor, and the picture in the book looks like mine without any hookups for a vacuum tube. This may be the upgrade.
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Old 08-05-2009, 02:02 PM
  #38  
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i have an 82 with out a vacuum advance and suffer VERY similar syndromes....
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Old 08-05-2009, 04:08 PM
  #39  
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hmmm...the SC should have two vacuum lines in fact. You can check with a timing light. If the timing is within spec, then you can move on down the list.
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Old 08-05-2009, 04:30 PM
  #40  
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The Bentley manual specifies advance with the vacuum hoses disconnected. I have my timing set to the Bentley specs, but I did not disconnect the vacuum hoses because I don't have them. I'm curious to know how the vacuum hoses affect the timing on other distributors. If I adjust my timing to the Bentley manual, I won't be getting any of the changes that re-connecting vacuum hoses might bring to the normal distributors.

If re-connecting the vacuum hoses is supposed to bring a change to the timing say another 5 degrees, then my timing would be 5 degrees off. I'll look around for timing specs for distributors without vacuum hoses.

- Andrew
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Old 08-05-2009, 05:11 PM
  #41  
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Originally Posted by aadrew10 View Post
The Bentley manual specifies advance with the vacuum hoses disconnected. I have my timing set to the Bentley specs, but I did not disconnect the vacuum hoses because I don't have them. I'm curious to know how the vacuum hoses affect the timing on other distributors. If I adjust my timing to the Bentley manual, I won't be getting any of the changes that re-connecting vacuum hoses might bring to the normal distributors.

If re-connecting the vacuum hoses is supposed to bring a change to the timing say another 5 degrees, then my timing would be 5 degrees off. I'll look around for timing specs for distributors without vacuum hoses.

- Andrew
Can you please post you findings here! Thanks!
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Old 08-05-2009, 05:30 PM
  #42  
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Time for Pete or Steve to chime in ..

I think the advance is actually performed by a couple of centrifugal weights in the distributor. I also thnk the second vacuum line ( the SC does have a single vacuum line up till about 80 , them it changed to 2 ) i think is just for emmisions during starting. Sounds like yours has definitely been modded. Does anyone know if the euro cars used vacuum advance lines ? a euro PET would tell us to.
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Old 08-05-2009, 06:11 PM
  #43  
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web browser search parameters:

[site:Pelicanparts.com "911 SC" "advance curve"]

"Early_s_man" "roninlb"

Here is an advance curve posted by RoninLB. I can't vouch for the accuracy, and I no longer have an SC to test or verify this with:

http://forums.pelicanparts.com/showthread.php?t=181402

Last edited by rusnak; 03-05-2010 at 12:15 AM.
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Old 08-05-2009, 08:21 PM
  #44  
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Just for kicks and giggles humor me. Tonight start the car in the garage and let it idle, pop the engine lid and shut the lights in the garage. If you see any sparks escaping from the wires near your distributor, your wires are shot.

My car needed wires and was running like crap, I changed the pickup coil in the distributor, the rotor, cap, wires, and plugs and it completely transformed the car. I took it one step further and removed the smog blower, that made the car run cooler, removed the cat, installed a bypass pipe and richened the mixture to 2.75% gas from 0.7%. The car runs very cool in operating temp, has lots of power, idles much smoother and does not suffer from idle hunting with the A/C on when the clutch is pressed in.

Check those ignition wires in the dark.
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Old 08-05-2009, 08:36 PM
  #45  
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I checked them a couple weeks ago in the dark and didn't see any sparks. My wires are the stainless braided shielded type, is it possible they are just arcing to the shielding and making the shorts undetectable?
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