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Seattle72
Samba Member
Joined: December 23, 2014
Posts: 41
Location: Oakland, CA
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 Posted: Mon Apr 20, 2015 9:44 pm Post subject: Vac advance help / air leaks / stutters and backfires |
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I've been searching for awhile and I need to ask for a little help because my head is spinning. A little background... I have a 1972 FI Squareback with the 231 172 009 stock distributor with pertronix. It was running poorly (very little power, poor acceleration). New VR (14.3v now), new NGK copper plugs, wires, cap and rotor. I replaced all the vacuum lines and clamped them. I tried to set timing, but my vac advance bottoms out on the tin before it was advanced enough and my idle screw is pretty far out from raising the idle. After this it was running better. Put my new vintage speed exhaust on Saturday and it was running great, better than ever. Sunday, while I was out driving, it started to stutter badly, backfiring and was hardly driveable (like there is a massive air leak). I checked all the vacuum lines and looks like no leaks. Pulled the plugs and they look good My questions is in regards to the vac advance. I pulled the advance hose to test it, blew into it and no movement on the arm. The plate in the distributor moves freely when you push on it. I also (after I removed the vac advance) tried to push in the arm then plug the line to see if it will hold and it has no effect. I can hear the diaphragm move inside when I blow in it, but no movement of the arm. The arm will move by hand, but it is really stiff.
Sorry this is so long, but I wanted to give as much info as possible. If I feather the throttle the car will drive, but as soon as I start to give it more gas it shutters and backfires. It makes sense in my crazy head this could be the cause. What do all of you think before I just start replacing things?
EDIT: I also checked the torque on the manifold runners and the injectors have no play in them, so I figure the seals there are good. And the backfire is more of a popping sound than a real exhaust backfire.
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1964 VW Beetle
my past loves....
1971 Super Beetle
1976 BMW 2002
1971 BMW 2002
1972 Squareback
1984 Rabbit GTI |
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Intrinsic
Samba Member
Joined: November 16, 2011
Posts: 262
Location: Clearwater, FL
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| Posted: Tue Apr 21, 2015 6:11 am Post subject: |
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| Its possible that your trigger points are not working correctly? This could impact fuel delivery timing. |
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Seattle72
Samba Member
Joined: December 23, 2014
Posts: 41
Location: Oakland, CA
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| Posted: Tue Apr 21, 2015 7:20 am Post subject: |
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I don't really know, I'll need to search to figure out how to test the trigger points and I will check that as well. Thanks
_________________
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1964 VW Beetle
my past loves....
1971 Super Beetle
1976 BMW 2002
1971 BMW 2002
1972 Squareback
1984 Rabbit GTI |
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sjbartnik
Samba Member
Joined: September 01, 2011
Posts: 5998
Location: Brooklyn
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| Posted: Tue Apr 21, 2015 7:29 am Post subject: Re: Vac advance help / air leaks / stutters and backfires |
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| Seattle72 wrote: |
I can hear the diaphragm move inside when I blow in it, but no movement of the arm. The arm will move by hand, but it is really stiff.
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Suck, not blow (vacuum).
There's a Spaceballs joke in here somewhere. |
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Seattle72
Samba Member
Joined: December 23, 2014
Posts: 41
Location: Oakland, CA
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| Posted: Tue Apr 21, 2015 8:44 am Post subject: Re: Vac advance help / air leaks / stutters and backfires |
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| sjbartnik wrote: |
| Seattle72 wrote: |
I can hear the diaphragm move inside when I blow in it, but no movement of the arm. The arm will move by hand, but it is really stiff.
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Suck, not blow (vacuum).
There's a Spaceballs joke in here somewhere. |
Oh I got it  I did suck on it as well and there is some resistance, but the arm does not move at all. Should I be able to get it to move?
_________________
------------------------------------------------------------
1964 VW Beetle
my past loves....
1971 Super Beetle
1976 BMW 2002
1971 BMW 2002
1972 Squareback
1984 Rabbit GTI |
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sjbartnik
Samba Member
Joined: September 01, 2011
Posts: 5998
Location: Brooklyn
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| Posted: Tue Apr 21, 2015 8:54 am Post subject: Re: Vac advance help / air leaks / stutters and backfires |
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| Seattle72 wrote: |
Oh I got it I did suck on it as well and there is some resistance, but the arm does not move at all. Should I be able to get it to move? |
Well it depends on how good you are at sucking (man this is going downhill fast).
If you get a good seal and suck hard you should be able to get the plate to move a bit. I doubt you'll be able to get it to move through its entire range of motion.
A better way is to use a handheld vacuum pump as then you can pull a better vacuum and see if it holds vacuum as well.
If you suck through the hose and air comes through like a straw, then you have a hole in your vacuum diaphragm and need to replace it. |
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Tram
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Joined: May 02, 2003
Posts: 22728
Location: Still Feelin' the Bern- Once you've felt it you can't un- feel it.
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| Posted: Tue Apr 21, 2015 10:06 am Post subject: |
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OP- did you check ignition point gap? Is it possible the rider wore closing the gap?
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Seattle72
Samba Member
Joined: December 23, 2014
Posts: 41
Location: Oakland, CA
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| Posted: Tue Apr 21, 2015 10:29 am Post subject: |
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sjbartnik- It is definitely not flowing like a straw, I am just not seeing any movement in the arm. I will try to hook it up to something to generate more suction. Maybe the advance is fine and I am barking up the wrong tree.
Tram- I have Pertronix in there so I don't think I have a point gap to check. I'm sorry if I am misunderstanding your question.
I am going to pull the trigger points to clean them tonight then put everything back together so I can fire it up and check the injectors. At least it starts every time and idles well. Thanks
_________________
------------------------------------------------------------
1964 VW Beetle
my past loves....
1971 Super Beetle
1976 BMW 2002
1971 BMW 2002
1972 Squareback
1984 Rabbit GTI |
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sjbartnik
Samba Member
Joined: September 01, 2011
Posts: 5998
Location: Brooklyn
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| Posted: Tue Apr 21, 2015 10:44 am Post subject: |
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| Seattle72 wrote: |
| sjbartnik- It is definitely not flowing like a straw, I am just not seeing any movement in the arm. |
Yeah but is it flowing at all? It shouldn't be. |
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blues90
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Joined: March 14, 2009
Posts: 1912
Location: Hollywood ,CA
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| Posted: Tue Apr 21, 2015 2:23 pm Post subject: |
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The vacuum advance will not make the engine run like that . mine has a bad unit won't hold vacuum yet it runs fine . It's really a fuel economy device.
If you can't set the timing and the vacuum advance hits the tin it sounds like you either have the plug wires in the wrong dist cap towers . You did replace the cap and wires so you might have then one over . This is to say instead of the #1 wire being in the proper # 1 place in the cap you might have it in #4 or you removed the dist drive gear and got it in wrong.
Somethings missing in your post you said it was running bad before then running better was this at idle because later you say it ran worse and backfired . is this what it was doing before you replaced all the parts? |
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Seattle72
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Joined: December 23, 2014
Posts: 41
Location: Oakland, CA
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| Posted: Tue Apr 21, 2015 3:59 pm Post subject: |
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blues... When it was running poorly when I first got the car, it had no power and was very sluggish. It would stumble a little bit as well, but it sort of felt like hesitations. It was driveable, just felt very heavy and struggled to get to highway speeds and up hills. This was after it had warmed up, cold it ran great. After changing all the vacuum lines, plugs/wires/cap/rotor, new fuel filter and some adjustment on the idle, it went almost completely away. Now it is stuttering badly under any load and popping sort of like a backfire, basically undriveable. It still does idle very nicely. Revved without load, you can hear it is not very smooth.
I could see how I might have the cables moved. The #1 cylinder should be at the mark in the distributor correct? And the I go clockwise 1-4-3-2?
EDIT: What I meant was...I'll check my Bentley for plug position and firing order
_________________
------------------------------------------------------------
1964 VW Beetle
my past loves....
1971 Super Beetle
1976 BMW 2002
1971 BMW 2002
1972 Squareback
1984 Rabbit GTI |
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blues90
Samba Member
Joined: March 14, 2009
Posts: 1912
Location: Hollywood ,CA
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| Posted: Tue Apr 21, 2015 6:34 pm Post subject: Re: Vac advance help / air leaks / stutters and backfires |
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| Seattle72 wrote: |
I've been searching for awhile and I need to ask for a little help because my head is spinning. A little background... I have a 1972 FI Squareback with the 231 172 009 stock distributor with pertronix. It was running poorly (very little power, poor acceleration). New VR (14.3v now), new NGK copper plugs, wires, cap and rotor. I replaced all the vacuum lines and clamped them. I tried to set timing, but my vac advance bottoms out on the tin before it was advanced enough and my idle screw is pretty far out from raising the idle. After this it was running better. Put my new vintage speed exhaust on Saturday and it was running great, better than ever. Sunday, while I was out driving, it started to stutter badly, backfiring and was hardly driveable (like there is a massive air leak). I checked all the vacuum lines and looks like no leaks. Pulled the plugs and they look good My questions is in regards to the vac advance. I pulled the advance hose to test it, blew into it and no movement on the arm. The plate in the distributor moves freely when you push on it. I also (after I removed the vac advance) tried to push in the arm then plug the line to see if it will hold and it has no effect. I can hear the diaphragm move inside when I blow in it, but no movement of the arm. The arm will move by hand, but it is really stiff.
Sorry this is so long, but I wanted to give as much info as possible. If I feather the throttle the car will drive, but as soon as I start to give it more gas it shutters and backfires. It makes sense in my crazy head this could be the cause. What do all of you think before I just start replacing things?
EDIT: I also checked the torque on the manifold runners and the injectors have no play in them, so I figure the seals there are good. And the backfire is more of a popping sound than a real exhaust backfire. |
I am a bit confused because you said after you replaced the cap, rotor , plug wires then installed the new exhaust system it was running better than ever yet before you installed the exhaust you said you could not move the dist enough , then you said you were driving it Sunday and it started back firing like it was running great one day then the next it wasn't .
If the timing was off it wouldn't run great on the road at idle it may run ok. From what you are saying I would check the plug wire position first and get the timing where it should be . If the wires are right then you have something else going on. |
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Bobnotch
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Joined: July 06, 2003
Posts: 22432
Location: Kimball, Mi
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| Posted: Tue Apr 21, 2015 6:35 pm Post subject: |
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| Seattle72 wrote: |
blues... When it was running poorly when I first got the car, it had no power and was very sluggish. It would stumble a little bit as well, but it sort of felt like hesitations. It was driveable, just felt very heavy and struggled to get to highway speeds and up hills. This was after it had warmed up, cold it ran great. After changing all the vacuum lines, plugs/wires/cap/rotor, new fuel filter and some adjustment on the idle, it went almost completely away.
EDIT: What I meant was...I'll check my Bentley for plug position and firing order |
Keep in mind that since you have a 72, you have to follow the timing settings given in Bentley. The 72 has a very specific way to set everything, and it has to be done that way, or it won't run correctly.
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Bob 65 Notch S with Sunroof
71 Notch ...aka Krunchy; build pics here;
http://www.thesamba.com/vw/forum/viewtopic.php?t=249390 -been busy working
64 T-34 Ghia...aka Wolfie, under construction... http://www.thesamba.com/vw/forum/viewtopic.php?t=412120
| Tram wrote: |
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| Tram wrote: |
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Max Welton
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Joined: May 19, 2003
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blues90
Samba Member
Joined: March 14, 2009
Posts: 1912
Location: Hollywood ,CA
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| Posted: Tue Apr 21, 2015 8:21 pm Post subject: |
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| The odd thing in the Bentley on page 55 all the dist are installed on a dist machine to find the vac and Mech advance yet for the 72 there is a note on the lower left of the page stating with the dist installed and again above that chart top right of the page table 1 it also states dist installed. I have to assume they mean installed in the car other wise why say this. |
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Seattle72
Samba Member
Joined: December 23, 2014
Posts: 41
Location: Oakland, CA
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| Posted: Tue Apr 21, 2015 8:49 pm Post subject: |
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| Max Welton wrote: |
When I look up 231 172 009 (apparently the Bosch number) at http://www.oldvolkshome.com/ignition.htm, the timing specs say:
| Quote: |
| Timing Set At: 5deg BTDC @ 800-950rpm w/strobe w/both vacuum hoses disconnected and plugged. When finished with timing and hoses plugged in, possible readjustment of idle to 850-900rpm may be needed |
For what it's worth.
Max |
I saw the same thing. Once I get the distributor cleaned up and installed, and the wires sorted out properly, I will be able to time it properly. Thanks!
_________________
------------------------------------------------------------
1964 VW Beetle
my past loves....
1971 Super Beetle
1976 BMW 2002
1971 BMW 2002
1972 Squareback
1984 Rabbit GTI |
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Mike Fisher
Samba Member
Joined: January 30, 2006
Posts: 17971
Location: Eugene, OR
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| Posted: Wed Apr 22, 2015 6:51 am Post subject: |
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You have to wire the distributor cap, so the vacuum can doesn't hit when trying to set the timing correctly. My vacuum can points to about 10:00 o'clock.
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69 FI/AT square Daily Driver
66 sunroof,67,70,71,71,71AT,72,72AT,73 Parts
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'68 Karmann Ghia sold
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blues90
Samba Member
Joined: March 14, 2009
Posts: 1912
Location: Hollywood ,CA
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| Posted: Wed Apr 22, 2015 12:10 pm Post subject: |
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I always make certain the dist drive gear is in the proper position so that #1 the rotor is facing the small line on the top edge of the dist body when #1 is TDC . In the Bentley it shows and tells you how it's done.
With that said you should have no issue with the vacuum can hitting anything to get it timed proper. |
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Bobnotch
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Joined: July 06, 2003
Posts: 22432
Location: Kimball, Mi
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| Posted: Wed Apr 22, 2015 7:35 pm Post subject: |
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| blues90 wrote: |
I always make certain the dist drive gear is in the proper position so that #1 the rotor is facing the small line on the top edge of the dist body when #1 is TDC . In the Bentley it shows and tells you how it's done.
With that said you should have no issue with the vacuum can hitting anything to get it timed proper. |
That's IF the PO installed it correctly (if the engine had been rebuilt). Most of the engine builders out there are familar with type 1 engines, and set the drive gear to that, which causes problems for type 3 owners. That 60* offset does make a difference. 
_________________
Bob 65 Notch S with Sunroof
71 Notch ...aka Krunchy; build pics here;
http://www.thesamba.com/vw/forum/viewtopic.php?t=249390 -been busy working
64 T-34 Ghia...aka Wolfie, under construction... http://www.thesamba.com/vw/forum/viewtopic.php?t=412120
| Tram wrote: |
| "Friends are God's way of apologizing for relatives." |
| Tram wrote: |
| People keep confusing "restored" and "restroyed". |
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Seattle72
Samba Member
Joined: December 23, 2014
Posts: 41
Location: Oakland, CA
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| Posted: Sat Apr 25, 2015 6:31 pm Post subject: |
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So I took the distributor out and cleaned it up, removed the trigger points and cleaned them with electrical parts cleaner and ran a piece of brown paper bag between the points. Checked my fuel pressure and it was just under 27 so I raised it to 29. Removed and reinstalled all the vacuum lines (just to be thorough). I even made a new gasket for the AAR from some EPDM I had around. I checked my timing and idle, idle is around 870. I didn't move my distributor because I wasn't 100% sure what to do, but the timing is just the slightest hair retarded (it's practically dead on 5deg BTD, I am probably splitting hairs) I actually tried to rotate it, but the vacuum hoses were in the way and I would have hit the little servo thing that is the throttle stop before I got far enough. And......... it runs like a champ!!! Idles great, throttle response and acceleration are good. Sweet  Thanks to everyone's help, I will be on my way to the PNW Springmeet tomorrow, Thanks!
Since I had lift access today, I also put on my new Sachs/Boge shocks and new upper ball joints. Handles great too!
_________________
------------------------------------------------------------
1964 VW Beetle
my past loves....
1971 Super Beetle
1976 BMW 2002
1971 BMW 2002
1972 Squareback
1984 Rabbit GTI |
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