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Technical & Safety: Distributor Troubles
 
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Pelican Technical Article:

Technical & Safety: Distributor Troubles

Lee Rice

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0 hours0 hrs

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Talent:

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Applicable Models:

Porsche 911 (1965-89)
Porsche 912 (1965-69)
Porsche 914 (1970-76)

Parts Required:

None.

Performance Gain:

General distributor tips and troubleshooting.

Complementary Modification:

None
     The question came up about ignition problems. There seemed to be more than one Porsche owner that had to replace their ignition distributor because the advance was not working. I was asked is this normal and was there any way to fix the distributor.

     It seems to be a normal practice to replace ignition distributors when the internal parts do not work right. The advance mechanism is usually suspect as it is subject to a great deal of heat and high frequency vibration. The requirements of a ignition distributor are very demanding and the least little wear and imperfection will cause odd behaviors.

     The installation of, a new distributor will usually return your Porsche to crisp performance, but they are not cheap. A new distributor for a 911 SC costing $800- 1,100 and the 1980 928 over 1,300! The re-built ones cost about a third of that.

     So what usually goes wrong? I have removed, disassembled, cleaned, inspected, lubricated, reassembled, and reinstalled and timed many ignition distributors. My observation is that the grease in the rotor and stator plate becomes old, dries up, and the stator plate seizes. This will cause the vacuum retard-or vacuum advance (for cold start-up) to be ineffective as the distributor will be stuck in one position.

     I did a major service on a 930 Turbo with this problem. When the engine first started it wouldn't idle at all. Finally the engine would burp and burbble up to something near running speed and as I accelerated the throttle a couple of times all of a sudden the engine accelerated to a high idle speed and stayed there with the throttle closed. Driving it was even more exciting as on one run it ran like a dog and the next run it accelerated very strong and "pinged" on boost. The culprit was a sticking rotor/stator plate. The normal cleaning and relubrication restored the engine to it's normal silky smooth running. This particular problem with the sticking rotor/stator plate seems to be common in the 1978 and later 911/930. Maybe the lubrication wasn't up to the demand of the emission requirements and the turbo heat.

     Once in a great while one of, the two, mechanical advance fly weight return springs breaks. The small and delicate bushings that fit over the fly weight spring retainers will break-thus reducing the springs tension and the advance will be too much for a given rpm. These problems can be repaired if you have the parts.

     The main reason to replace a distributor is for worn distributor shaft bushings. When the bushing wears out the rotor will fly out of it's track and hit the distributor cap contractors. This can and eventually will break the distributor cap. The bushings can be replaced-if you can find them. If you are driving an old Porsche it would be a good idea to keep en eye open for a used distributor at the swap meets. You may find a perfectly good distributor but at least you will have some serviceable Darts.

     The choices for replacing or repairing are one of time and costs. I prefer the warranty re-built as long as the part numbers are the correct match. If the vacuum advance-retard units work correctly and the problem is old grease causing a sticky vacuum advance/retard, I wold have your distributor repaired, this shouldn't cost much more than a hundred bucks.

     930 Turbos: When making timing adjustments to the 930 Turbo you should be aware that the large vacuum unit on the ignition distributor do three things that all need to work together. All turbos have a vacuum retard feature. This retards timing at idle only with the throttle fully closed. As soon as the throttle is opened this retard is gone and the timing advances.

     The second vacuum feature is on the opposite side of the vacuum unit. This vacuum is used to advance the timing for cold start and warm-up. This vacuum supply is controlled be a electric switch for ('77-82) and by a thermal switch on the breather cover('83-95). The third source is boost pressure. The 1978 California specification Turbo and all later ones require the high rpm timing check done at 4,000 rpm with the vacuum retard hose disconnected. This timing at 4,000 is taking into consideration that the vacuum unit is fully operational and at 0.5 bar boost it will retard the timing by 4-6 degrees. The workshop manuals do not give you a performance check of this, but I would recommend that this be checked. Especially if you encounter roughness and pinging when on boost. This will melt expensive things!

     Lee Rice writes the monthly Technical & Safety column for the Orange Coast PCA (zone 8) Newsletter.  He has generously allowed Pelican Parts to republish these articles here for the benefit of everyone who visits the site.
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Comments and Suggestions:
Jerry Comments: 1983 911SC After setting up a while, had erratic starting. Either started instantly or mostly would not start. My mechanic just replaced the CDI, Coil & spark plugs. Now the car starts, but is hard to start. It seems to only start when I let off the start & key returns to on position. In the past, it would start instantly. The mechanic says it is in the ignition switch. I wonder if the CDI is bad. Does the CDI increase voltage for startup like some cars do? Thanks
February 10, 2016
  Followup from the Pelican Staff: if it is the ignition switch, you can confirm by monitoring the voltage out of it when the problem is present.

When your engine doesn’t start you’ll want to check the basics. Check spark, fuel injector pulse and fuel pressure, volume, quality and engine compression. Once you figure out what is missing, it will be easier to diagnose.
- Nick at Pelican Parts
 
Jorge Comments: Hi
i have a 1972 911... there is no spark at distributor and neither any voltage at ignition coil. engine crancks but won't starts. fuel pump is working...
can you help me?

December 28, 2015
  Followup from the Pelican Staff: Check the resistor relay, it sends power to the coil. - Nick at Pelican Parts
Alex Comments: CDI was blown! Up and running!
August 29, 2015
  Followup from the Pelican Staff: Awesome. Thanks for the follow up. - Nick at Pelican Parts  
Alex Comments: by the way engine is 2.7 1976
August 23, 2015
  Followup from the Pelican Staff: ok, got it. - Nick at Pelican Parts  
Alex Comments: Hi! So what happened is I was cheking copression, disconnect ignition coil and when connect everything back, the ignition coil does not produce hi woltage power, i checked if there is 12v go to ignition coil when engine crancking and there is not. Totally frostrated.. what can be a problem? ignition unit? any fuse? ignition relay?
August 23, 2015
  Followup from the Pelican Staff: Trace the wire from the coil backward, it may become disconnected during the procedure. - Nick at Pelican Parts  
Hil911 Comments: I have a 1976 911S. I have an irregular misfire that I can't track down - my spark coil produces a spark noise inside when the DC system fluctuates. I am considering installing a Pertronix system and coil, bypassing the original system and CDI, for diagnostics. Is that reasonable?
October 6, 2014
  Followup from the Pelican Staff: before replacing any parts. confirm the issue is in fact spark. I would check spark, fuel and compression on all cylinders.
- Nick at Pelican Parts
 
Arum Comments: I have problem with my 930 1987, when the engine is fully warm the rpm went up and down + or- 100 rpm not much and went test driven it move very sluggish and lack of power. I have replaced vacuum situated at the distributor and WUR. But the problem still persist- please help. Thanks
September 10, 2014
  Followup from the Pelican Staff: I would perform a fuel delivery system test. Check fuel pressure, volume and quality.
- Nick at Pelican Parts
 
John914somers Comments: I bought a distributor belt from Pelican for the dual distributors of my 97 993 but I can't locate a procedure for replacement of it and it does not tell how to replace it in the repair manual that I purchased from pelican either. Can you tell me where I might be able to locate information on this procedure. Tanks a ton!
May 12, 2014
  Followup from the Pelican Staff: What repair manual are you using? I don't think it is in the Bentley manual, in Porsche stuff, it may be there. The procedure requires removing the distributor, then removing the distributor shaft. I will see if I can locate a distributor myself and perform the procedure. If I find one, I will be sure to document the process.- Nick at Pelican Parts  
Opalized Comments: Dear Nick:
I have replaced the coil, straight wired from battery to coil then to points, via condenser of course, old coil new coil same story, also i made sure and bought a internal resister coil not knowing what prior coil was, and noticing when i purchased a pep boy special it was external resister required type coil, this weekend i purchased an 009 dist mechanical only no vacuum, and new bosch cap and rotor, no change, off idle the car runs exceptional, very good throttle response, begins to blow back through carbs over 6000 rpms, and basically no more power
March 31, 2014
  Followup from the Pelican Staff: I would check the carb adjustments. If you have spark, it could be a fuel delivery issue. Over 6000, it may be running out of fuel. Likely not fueling correctly at idle. - Nick at Pelican Parts  
Opalized Comments: Ec block 1800 cc porsche 914, performance cam, 96mm juggs, 49mm intake, 38mm exhaust valves, 34 mm ict Weber carbs, having an issue with no spark and or fire during idle on 2 back cylinders, new wires, cap rotor, plugs, coil, rebuild carbs, no vacuum leak, good fuel, fresh rings, equal compression 60 lbs one revolution, 90 lbs 4 revolutions cold motor, straight wire battery to coil, then coil to point, and or electronic ignition, vacuum at intake top base carb, needle 0 to 14 fluctuating, tap throttle on deceleration goes to 14.5, then begins o to 14 bounce again, 2000 rpms, minut fluctuation at 14 lbs vacuum steady, valve adjustement .06 cold, checked and rechecked, any suggestions
March 27, 2014
  Followup from the Pelican Staff: is the coil firing the entire time? Or does it cut out? - Nick at Pelican Parts  
fastlane914 Comments: I have a 1973 914- 1.7 with 32/36 carbs. Acceleration is sluggish to the point of having the engine almost die. It may be the distributor vacuum. Is there a good way to check the vacuum from distributor?
thanks,
November 30, 2013
  Followup from the Pelican Staff: Check vacuum at the intake manifold both before and after the throttle valve. Also check timing advance at the distributor using a timing light and with a vacuum pump attached to the distributor vacuum can. - Nick at Pelican Parts  
DanPez Comments: Scratch the last comment .... I wast pulling the housing hard enough. An O-ring keeps it tight in its place. Mechanism inside was binding preventing the advance to work properly. I put a bit of anti-seize when I installed it back. Next time it should be easier to pull out.
September 27, 2013
  Followup from the Pelican Staff: Thanks for the follow up. - Nick at Pelican Parts  
DanPez Comments: Hi, I have a 1973 911T 2.4L that's having issues with the advance adjustment. Vacuum diaphragm or link to the rotor does not work on the distributor assembly At the same time the TDC is not aligned with #1 contact. Therefore I'd like to remove the whole distributor from the crank to inspect the gear and any play on the shaft.
I removed the 13mm adjustment nut and was expecting the complete distributor assembly to come out.
Is there an allen key or bolt somewhere preventing me to remove it completely?
Thanks
September 27, 2013
  Followup from the Pelican Staff: I am placing your follow up here:

Scratch the last comment .... I wast pulling the housing hard enough. An O-ring keeps it tight in its place. Mechanism inside was binding preventing the advance to work properly. I put a bit of anti-seize when I installed it back. Next time it should be easier to pull out. - Nick at Pelican Parts
 
Lee Comments: I have a 1978 911SC Targa, while driving when the weather is warm the engine will stop running, all the gauges are still on because the key is still in the on position, I'm usually on the highway, I turn the key off then back on and the engine fires up and starts running normally again. I changed the relay for the fuel pump and this does not happen as often, but it happened again today. It seems to me that when I turn the key off I'm resetting something in the ignition system, any idea's???
August 18, 2012
  Followup from the Pelican Staff: You'll want to check to see what you are missing when the engine doesn't start. Then check for power to that components. - Nick at Pelican Parts  
GTwizard Comments: I need a vacuum line diagram for a 1982 911SC.
There are 2 vacuum port on the rear of the throttle body and 2 on the front. Where do these plumb to.
May 17, 2012
  Followup from the Pelican Staff: Try this discussion:

http://forums.pelicanparts.com/porsche-911-technical-forum/467417-key-911sc-vacuum-hose-diagram.html - Nick at Pelican Parts
Porsche 914 Comments: I have a '73 914 2.0 and I am trying to get it started after sitting in a barn for 18 years. I replaced the distributor rotor and am hoping that I put the new one on correctly. Inside the rotor there is a little triangle nub which I put in the notch of the cam. does this sound correct?
February 2, 2012
  Followup from the Pelican Staff: You will align the distributor shaft notch with the rotor tab. - Nick at Pelican Parts  
John Comments: I have a 1980 911 with a 3.2 I'm not getting spark at spark plug. car will start and run beautifully then will die with no spark.......any ideas? how can I test coil.? Bentleys manual says to test coil but does not say how Many thanks John
November 27, 2011
  Followup from the Pelican Staff: The coil should have power on one side. Then the other side should pulse when you try to start it. Test it using an incandescent test light.- Nick at Pelican Parts  
weeli Comments: the car is carrera 996 1998 .. engine ok everything just change and renew. wiring setting had been done.. but it still wont start..
August 11, 2011
  Followup from the Pelican Staff: I can't help without knowing what is missing from the system when you are trying to start it. When your engine doesn’t start you’ll want to check the basics. Check spark, fuel injector pulse and pressure fuel, volume and quality. Once you figure out what is missing, it will be easier to diagnose.
- Nick at Pelican Parts
 
weeli Comments: how do you repair this when basically everything is going smooth but it wont start? starts only when fast injection?
August 11, 2011
  Followup from the Pelican Staff: What are you trying to repair? - Nick at Pelican Parts  
TIM Comments: 914 1974 PORSCHE 1.8 CANT GET FIRE==== FUEL PUMP RUNS AND IT TURNS OVER BUT NO SPARK. NEW COIL DID NOT HELP
July 24, 2011
  Followup from the Pelican Staff: Check for power to the coil. If power is present, check that the other side of the coil is pulsing when try to start the engine. Use an incandescent test light. If the coil signal is good, the ignition control module may be faulty. - Nick at Pelican Parts  
Jimbones Comments: Where is the distributor number on the Bosch unit in my '72 911? I want to be sure I order the right ignition parts, and don't see any numbers on the thing. Do I have to remove the distributor to see the number stamp? Thanks
March 23, 2011
  Followup from the Pelican Staff: It should be printed on the side, you might have to remove it to see the numbers, or you can use a flashlight and a small inspection mirror. - Wayne at Pelican Parts  
Bulldog Comments: Hey,need a twin plug ignition system incluiding a twin plug distribuitor.Someone out ther,I need to have my distribuitior repair,is a 76 3.0 carrera ,
October 18, 2010
  Followup from the Pelican Staff: Give our parts specialists a call at 1-888-280-7799. They can help you find the right part.
- Nick at Pelican Parts
 
malcolm Comments: need a vacuum advance can for 1980 911sc bosch distributer with dual vacuum lines
September 17, 2010
  Followup from the Pelican Staff: Give our parts specialists a call at 1-888-280-7799. They can help you find the right part.
- Nick at Pelican Parts
 
don Comments: I just need to replace the distributor clamp on my distributor for my 1972 porsche 914. I have the clamp and the workshop manual. It tells me I have to remove the pin and use a vice, etc. Can I do that without a vice? I don't have one and I'm afraid to try. That's all I am concerned about. Can this be done by a court reporter with few tools?
September 11, 2010
  Followup from the Pelican Staff: I don't think that you need a vice, but you do need a method to hold it down. It might be a good time to buy a vice, they are pretty cheap at Sears and quite useful for around-the-house tasks. - Wayne at Pelican Parts  
bob o Comments: i purchaced a 71 914 which was fi trashed and now have the engin working. now, i need to get the rpm working can you help

bob
August 1, 2010
  Followup from the Pelican Staff: Have you checked the tach signal to the tachometer? - Nick at Pelican Parts  
tt930 Comments: Article question -
" So what usually goes wrong? I have removed, disassembled, cleaned, inspected, lubricated, reassembled, and reinstalled and timed many ignition distributors. My observation is that the grease in the rotor and stator plate becomes old, dries up, and the stator plate seizes. This will cause the vacuum retard-or vacuum advance for cold start-up to be ineffective as the distributor will be stuck in one position."
I would love to see some pics or diagram illustration as to how to service the distributor, any chance posting some step tp step picture guide ? or Video even !?
February 10, 2010
  Followup from the Pelican Staff: If we get the chance we will post photos or a video. Thanks for th e feedback. - Nick at Pelican Parts  
turbo 930 Comments: I have a '78 930 that I can't start after rebuilding the dist. Forget to mark my position. Now I can't find number 1 plug. there are 3 notches on crankshaft pulley. there is a Z1 and another one next to it abt 5deg to the right and then 2 others somewhere. whats the best way to find the right one?
December 9, 2009
  Followup from the Pelican Staff: Do you have the 101 Projects book? The distributor wire mapping is in there... - Wayne at Pelican Parts  
BC Auto Comments: Have you ever completely disassembled the distributor in a 1978 911 targa. We were told that there are special tools needed to change the pickup coil in the distributor.

Thank you
October 19, 2009
  Followup from the Pelican Staff: There's a gear that's pressed onto the end of the shaft of the distributor, so you need a small press to completely disassemble the entire distributor, but I don't think there are any special tools required to get to the pickup? On the later 964 distributors, some of them are more difficult to take apart, maybe that person was slightly confused? - Wayne at Pelican Parts  
BC Auto Comments: Have you ever put a pick up coil in a 1978 911sc targa?
October 13, 2009
  Followup from the Pelican Staff: I'm sorry, I'm not sure what that is. Do you mean electronic, breakerless ignition? - Wayne at Pelican Parts  
porsche911t Comments: looking for some help ,dist. in 911t 69 . two wires red and black .bosch dist. needing a pic. or diagram for troubleshooting.
July 31, 2009
  Followup from the Pelican Staff: I opened a post in our forums. A Pelican community member may be able to answer your question.
- Nick at Pelican Parts
 
930 porsche Comments: Do you have a schematic on the 1978 930? I just need to see where those 2 vacum line go to?

Thank you.
July 21, 2009
  Followup from the Pelican Staff: There is some great info here:
http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/611396-distributor-vacuum-lines-smog-removal.html - Nick at Pelican Parts

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