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Intermittent Spark?
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Tooster
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PostPosted: Wed Sep 19, 2012 7:30 am    Post subject: Intermittent Spark? Reply with quote

73 Westy. Camper Special (9000 miles). 40 EMPI carbs. SVDA Distributor with Pertronix. NGK Plugs gapped at .30.

I have been chasing a rough idle (caused by #1) for a while, then a few months ago, it went away and had been running great. The cause then seemed to be a corroded dist. cap (green-ish, especially on #1), sanded down, then new dist cap and rotor and all seemed to good.

Last week, on the way back from a short (5 miles) drive into town, the bus started running poorly, and CHT gauge to #1, dropped to 200.

I have had blocked idle jet issues before, so, I assumed that was the case, blew it out, seemed to run better in the driveway, but took it out for a drive down the street, same problem, but maybe worse.

Took off carb, blew it out. Same rough idle. Pulled #1 plug and spark was intermittant, then seemed to disappear completely at times. Engine doesn't seem to respond much when I pull the plug wire. Timing light was bouncing some, seemed to confirm issue. Seems to get worse when warm, so checked coil (seemed ok), but replaced anyway, replaced plug wires. Same thing - especially when warm. Checked compression on #1 and #3 - both 100.

Disy advance has always been a bit "bouncy" and now doesn't seem to move (timed at 7.5 and I can only seem to get advance to 24 or so). Dissy isn't that old - 15,000 miles or so.

Battery needs to be replaced (still starts, but obviously getting weak). Could that be the problem or is it obviously, the dissy? Anything else?
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SGKent Premium Member
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PostPosted: Wed Sep 19, 2012 7:54 am    Post subject: Reply with quote

if 2,3 and 4 are Ok then replace the wire and plug on 1. Make sure the wire that you have now is pushed all the way down into the cap before you make your final determination. You might be able to see a halo around it or it shorting to ground if you look at it in the dark. If that doesn't get it try replacing the sender on the electronic ignition as one of the lobes may have a bad magnet in it.
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Desertbusman
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PostPosted: Wed Sep 19, 2012 7:58 am    Post subject: Reply with quote

Tooster wrote:
Disy advance has always been a bit "bouncy" and now doesn't seem to move (timed at 7.5 and I can only seem to get advance to 24 or so).

What is bouncy, the vacuum advance or the mechanical advance? Have you timed it the way that is continually talked about here of the Samba? By removing the vac line to the distributor vacuum pod and timing it a about 29 degrees BTDC at max advance which would be around 3,200 - 3,500 rpm. You don't time it at idle.

The mechanical advance shouldn't "bounce". If that doesn't start to reveal what your problem is I'd try something else. And that would be to rotate your distributor 90 degrees in which ever direction you can do it and then rotating the plug wires around the cap one position to correspond with the repositioning of the dizzy. Time it at max mechanical advance and see if the problem remains with #1 cylinder.
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The best thing that anyone can do for their Bay is get the Volkswagen of America Official Service Manual published by Robert Bentley. Without it the bus is pretty much doomed.
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when that red light goes on, you have to make a choice.
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I am not answering that.
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Tooster
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PostPosted: Wed Sep 19, 2012 8:01 am    Post subject: Reply with quote

I replaced all the wires. Didn't seem to make much difference.

On the shorting to ground - look at the cap?

When you say "replacing the sender" on the Pertronix, what do you mean? I put that in years ago - do you mean the magnet ring on the dissy shaft? That would explain it. I had always heard that the Pertronix don't have partial failures.

Would that explain the lack of advance I seem to be seeing?
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Desertbusman
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PostPosted: Wed Sep 19, 2012 8:06 am    Post subject: Reply with quote

Tooster wrote:
Would that explain the lack of advance I seem to be seeing?
No, that is a problem with the Dizzy itself and has nothing to do with whether you have points or a Pertronix.

Rotating the distributor like I mentioned would tell if there is a problem with the magnet ring.
_________________
The best thing that anyone can do for their Bay is get the Volkswagen of America Official Service Manual published by Robert Bentley. Without it the bus is pretty much doomed.
73kombi wrote:
when that red light goes on, you have to make a choice.
Amskeptic wrote:
I am not answering that.
Respectfully,
GoBuyABentley

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Tooster
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PostPosted: Wed Sep 19, 2012 8:12 am    Post subject: Reply with quote

Desertbusman

Timed it they correct way (hose plugged, etc.). The bounce is on mechanical (both really), but back when I could get it to 28, it would bounce between 26-28 or so. It had not always done that - last year or so. I only seem to be betting about 16 of advance now 0 I have always been able to time at about 7.5 with mech advance to 28. Seems like something is stuck or Pertronix not working.

I am trying to understand why that would only be effecting one cylinder - unless its the lobe issue.

Good idea on moving the disy and wires forward - that should isolate the problem.

Would it make sense for me to put the points in as a check (I have about 3 sets laying around)?
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Tooster
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PostPosted: Wed Sep 19, 2012 8:19 am    Post subject: Reply with quote

I will admit that I did forget and left the key on several months ago as I was working on something.

I have read that can burn out the coil and/or Pertronix. However, I checked the old coil and it passed (and I have now replaced it) too, so that's not it. On the Pertronix, I didn't think it was possible to have a partial failure.

I will either put the points in - or move the dissy and wires forward. However, as Desertbusman said, lack of consistent spark to #1, shouldn't have anything to do with the lack of advance.
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Desertbusman
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PostPosted: Wed Sep 19, 2012 8:24 am    Post subject: Reply with quote

Tooster wrote:
Desertbusman

Timed it they correct way (hose plugged, etc.). The bounce is on mechanical (both really), but back when I could get it to 28, it would bounce between 26-28 or so. It had not always done that - last year or so. I only seem to be betting about 16 of advance now 0 I have always been able to time at about 7.5 with mech advance to 28. Seems like something is stuck or Pertronix not working.

I am trying to understand why that would only be effecting one cylinder - unless its the lobe issue.

Good idea on moving the disy and wires forward - that should isolate the problem.

Would it make sense for me to put the points in as a check (I have about 3 sets laying around)?
Bouncing is a dizzy problem. Have you taken it apart, inspected and lubricated it? No need try points if you can't even time it the right way or if you have the timing bounce. Rotating it 90 degrees will allow the Pertronix (or points) to be using a different lobe on the cam. And by doing that switching it would change your #1 problem to another cylinder if it's a dizzy problem.
But if you can't even time it don't expect the problem to be elsewhere.
_________________
The best thing that anyone can do for their Bay is get the Volkswagen of America Official Service Manual published by Robert Bentley. Without it the bus is pretty much doomed.
73kombi wrote:
when that red light goes on, you have to make a choice.
Amskeptic wrote:
I am not answering that.
Respectfully,
GoBuyABentley

71 Superbug
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Tooster
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PostPosted: Wed Sep 19, 2012 8:28 am    Post subject: Reply with quote

I have lubed it, but haven't taken it apart since I installed the Pertronix - 3-4 years ago.

I will start there and report back. Thanks.

The Mallory has been on my wish list for a long time, maybe this is just what I need to make that happen!
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PostPosted: Wed Sep 19, 2012 8:34 am    Post subject: Reply with quote

Tooster wrote:
as Desertbusman said, lack of consistent spark to #1, shouldn't have anything to do with the lack of advance.

Did I say that?

Quote:
The Mallory has been on my wish list for a long time, maybe this is just what I need to make that happen!
What needs to be on your wish lis is just a distributor that doesn't bounce and the timing can be set on it. Such as a good SVDA.
Don't worry about the Pertronix at this point.
_________________
The best thing that anyone can do for their Bay is get the Volkswagen of America Official Service Manual published by Robert Bentley. Without it the bus is pretty much doomed.
73kombi wrote:
when that red light goes on, you have to make a choice.
Amskeptic wrote:
I am not answering that.
Respectfully,
GoBuyABentley

71 Superbug
71 Westy
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SGKent Premium Member
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PostPosted: Wed Sep 19, 2012 8:35 am    Post subject: Reply with quote

First make sure that the ring is still firmly seated and not loose on the distributor lobes. Make sure that the pickup is still firmly screwed down and that it has not come loose. Check to see that the ground wire for the plate is still intact. If those things are all Ok, then turn the engine by hand with the key off inspecting the air gap between the ring and the pickup for each cylinder. While you are at it, pull the rotor and put a few drops of oil on the wick under the rotor as that lubricates the mechanical advance. If all those things are good and you don't see an obvious problem then you can try DBM's suggestion or put points back in. I don't know how happy the sender ring will be about being removed then reinstalled after being on for such a long time.
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Tooster
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PostPosted: Wed Sep 19, 2012 10:24 am    Post subject: Reply with quote

Desertbusman: On the "Did I say that" question. I interpreted the following that way:

Tooster wrote:
Would that explain the lack of advance I seem to be seeing?

No, that is a problem with the Dizzy itself and has nothing to do with whether you have points or a Pertronix

I'm just trying to understand the relationship (if any) between not sending a consistent spark and what appears to be a lack of advance. This level of detail is new to me, so just trying to wrap my head around how the symptoms fit together - or not. I was thinking that not sending a spark to #1, might be related to lack of advance, but it seems like they wouldn't be related.
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Tooster
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PostPosted: Wed Sep 19, 2012 10:36 am    Post subject: Reply with quote

What I also meant to say is that whether a bad lobe/magnet not sending a consistent spark to #1 is related to a general lack of advance might not matter. I was hoping they were related, since that would point to a single dissy problem. However, I think it seems clear that the distributor is the root of the problem.

I will take it apart tonight and report back. Thanks SGKent and Desertbusman.
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PostPosted: Wed Sep 19, 2012 10:41 am    Post subject: Reply with quote

the problem with electronic ignition is that when it malfunctions it can look like other issues. Timing scatter for example can mask what the real timing is. Until you have a steady timing mark you can't really judge whether the timing is moving. Also - you set timing on #1 but if it is not working right you don't have a reliable signal there. Hook the light up to #3 and see what timing you get. See if that is stable.
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Desertbusman
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PostPosted: Wed Sep 19, 2012 12:22 pm    Post subject: Reply with quote

Quote:
Disy advance has always been a bit "bouncy" and now doesn't seem to move (timed at 7.5 and I can only seem to get advance to 24 or so).
It appears as if you initially have two problems. The way you set the timing and then maybe an advance mechanism problem. Rev it up to the 3.500 and set the timing at 29 BTDC (W/O vac hose). Then drop it down to idle and see if the advance drops down somewhere around 7.5. If it doesn't then there is an advance mechanism problem. No matter what any other problems might be it won't be good without timing and a working advance. That has nothing to do with the Pertronix.
The next thing is trying to find out why #1 isn't firing right. It might have something to do with the cylinder or the ignition. If you're sure the plug, wire, cap, and rotor are good (did you swap out the plug?) then putting your timing light on #3 wire is a good way to see what kind of consistancy you're getting with the spark. You pulled #1 plug wire and it didn't affect the engine speed. We assume you also pulled the other plug wires and it did affect the speed.
If you do the "pull the plug wire test" again also try it at a higher engine speed. Dual single barrel carbs don't always equally feed and fire all cylinders at idle. My #1 and #4 don't fire at a slow idle.
_________________
The best thing that anyone can do for their Bay is get the Volkswagen of America Official Service Manual published by Robert Bentley. Without it the bus is pretty much doomed.
73kombi wrote:
when that red light goes on, you have to make a choice.
Amskeptic wrote:
I am not answering that.
Respectfully,
GoBuyABentley

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Wildthings
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PostPosted: Wed Sep 19, 2012 12:34 pm    Post subject: Reply with quote

Pull the dizzy out and check that the thrust washers between the housing and dog gear on the end of the shaft are all there. If they are missing, which is common, this will allow the dizzy drive to walk up and down which will cause the timing to jump around.

Have you oiled the felt under the rotor recently. This is supposed to be oiled every 10,000 miles or so.
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PostPosted: Tue Sep 25, 2012 12:29 pm    Post subject: Update Reply with quote

I took the distributor out. Wiped it out. Blew it out with compressed air. Checked to make sure all 4 magnets in the Pertronix worked. Sucked on the vacuum can made sure it was moving, and manually moved the plates.

Put it back in, timed it to 28 (hoses off). Still have a slight bounce at about 28 (2 degrees or so). Initially it dropped back to around 8 (perfect), but as it warmed up more (and I kept running it back up to 28 to check), it settled in around 12. So it looks like I am getting about 16 degrees of advance. #1 spark was solid and didn't fall off once it got warmed up like before.

Dumb question, but should #3 time at the exact same degree as #1? I ask, since I followed the advice above and while #1 timed at about 8-12 degrees at idle, #3 seemed to idle at about 16 degrees. #3, correspondingly, advanced to around 32 degrees when #1 advanced to 28.

Good news is that I took it for about a 10 mile ride and it ran great, with all temps (CLT on #1 and #3) running same as always and OT and OP all in line.

What does this mean?
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PostPosted: Tue Sep 25, 2012 12:38 pm    Post subject: Reply with quote

And all thrust washers appeared to be there. There is a bit of up and down movement when I pulled up on the rotor (it springs back) - I assumed that is normal, but maybe not?
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Wildthings
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PostPosted: Tue Sep 25, 2012 2:49 pm    Post subject: Reply with quote

Tooster wrote:
And all thrust washers appeared to be there. There is a bit of up and down movement when I pulled up on the rotor (it springs back) - I assumed that is normal, but maybe not?


A small amount of up and down movement is normal, maybe a 1/32 of an inch. More movement than that would indicate that the washers inside the distributor body may have failed. Yes the rotor should spring back when turned.
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PostPosted: Tue Sep 25, 2012 3:38 pm    Post subject: Re: Update Reply with quote

Tooster wrote:
... but should #3 time at the exact same degree as #1? I ask, since I followed the advice above and while #1 timed at about 8-12 degrees at idle, #3 seemed to idle at about 16 degrees. #3, correspondingly, advanced to around 32 degrees when #1 advanced to 28.

Good news is that I took it for about a 10 mile ride and it ran great, with all temps (CLT on #1 and #3) running same as always and OT and OP all in line.

What does this mean?


Alledgedly, on a non doghouse 1600, #3 is retarded a bit because the oil cooler blocks cooling air to #3. If this is true, and knowledgeable people will confirm it, #3 should be about 5 1/2 at idle and #1,2,4 will be at 7 1/2. I haven't compared the timing on my 205T distributor with points, but I assume I would see a timing difference between #3 and the other cylinders. I assume Pertronix does not arrange their magnets to achieve this and a non doghouse 1600 #3 will not be retarded and may be subject to overheating or a burned exhaust valve if a Pertronix is used.

Most likely you have a mechanical problem within your distributor.

Aloha
tp
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