[T3] Ignition on with points closed.

Tue Mar 29 17:16:32 PDT 2016

Don, please explain how the points will get burned even if they are closed
while the ignition is on and the engine is not turning.  Virtually all the
energy would be dissipated in the 4 Ohm primary coil winding, and while I've
never measured the resistance of a set of points, I can't believe it could
be more than a tiny fraction of the coil resistance, maybe 0.1 or 0.2 Ohms,
so don't see how there could be a significant amount of heat dissipated in
the points, let alone enough to burn them. 
I've never experienced burnt points even though the ignition would have
occasionally been on for some time, eg when adjusting headlight aim, and
I've never bothered to ensure the points are open.  Certainly the coil would
warm up, as it dissipates about 40W with the engine static, and about 20W
when running (figures from Motor Industry Research Association report on
1969 FI Auto Fastback), so unless your hands are cold, there's no advantage
in it!

Obviously there's no gain leaving the ignition on unnecessarily, but I can't
see how it would be a problem for the points, which are essentially just
switch contacts.  Please explain if I'm showing my ignorance, but it sounds
like something told to apprentices to emphasise the need to turn off the
ignition and avoid flat batteries.

Dave
UK VW Type 3&4 Club
===================

----Original Message-----
From: type3-vwtype3.org [mailto:type3-vwtype3.org-bounces at lists.vwtype3.org]
On Behalf Of Don Robertson
Sent: 29 March 2016 13:36
To: type3 at vwtype3.org
Subject: [T3] Ignition on with points closed.

Having the ignition on for any appreciable amount of time when the points
are closed will burn the points.  If you need the ignition on, pop the
distributor cap and turn the engine so the points are open, then there will
be no harm.  Or disconnect the wire that goes from the coil to the
distributor.

A bad condenser will also cause the points to burn quickly, but is a rare
occurrence, unless of course the condenser is a new Chinese one.

At 08:12 AM 29/03/2016, you wrote:
>Ignition on without the engine turning will either be powering the coil 
>or not, depending on whether the points are open or closed. It won't 
>have done any harm to the points either way.  Is the heel and cam 
>lubricated?  High performance ignition coils tend to produce more erosion
of the points.
>
>Keith says your sensor for AFR is not sited correctly (or is that 
>someone
>else?) - seems to me if he's right you're placing too much reliance on 
>its readings.  MPG over a decent distance must be a better guide.  Plug 
>colour too will help, as will feel of the engine response.
>
>My FI Fastback performance is very sensitive to timing, but it has the 
>twin vac advance (as does my twin carb Variant, but that doesn't seem 
>so sensitive).  When it was hunting, I enrichened the MPS slightly, 
>then reduced it again a few months later when a CO meter showed it was
around 1%.
>It went back down to less than 0.5% and no hunting!
>
>Keep enjoying driving it, and let it grow old gracefully!
>
>I used to worry about the sound of my 7-year-old Beetle engine 50 years 
>ago, so my parents bought me a Blaupunkt radio for my 21st birthday! A 
>few months later at 50,000 miles I had to have a new camshaft as two 
>cam followers had worn through to the oilway - expensive!  Ah, the joys 
>of VW motoring back then, and I am still committed to them!
>
>Dave
>UK VW Type 3&4 Club
>===================
>
>-----Original Message-----
>From: type3-vwtype3.org 
>[mailto:type3-vwtype3.org-bounces at lists.vwtype3.org]
>On Behalf Of Daniel Nohejl
>Sent: 29 March 2016 12:16
>To: type3 at vwtype3.org
>Subject: Re: [T3] Bad day at the (FI) office
>
>snipped
>
>Anyway, in general, things seem to be better. We went away over the 
>weekend and on the way out of town, we leaned out the MPS a wee bit 
>closer towards its original position. Our highway cruise AFR is kind of 
>lean..anywhere from
>14.5 to 16.5 but our MPG over the 260 miles was a modest 25.8. I 
>imagine if we were too lean, our MPG would have been much higher.
>
>Toward the end of the trip, I started noticing that the idle AFR went 
>back to rich even though we hadn't touched it again and that the idle 
>sounded too high. When we got home, we took out the dwell meter and 
>timing light. First, the idle was at 1020 rpm so we brought it down to 
>850 but it was unstable and hunted slightly so we brought it up to 
>around 900 which is where it seems happiest. We noted that the dwell 
>had changed from 48* to 52* in 1600 miles. I've never had that happen 
>before. Also, the timing was a few degrees advanced..closer to the 
>second timing mark than the first. We tried to reset the points but 
>there was such a big tit on one side that it was hard to get the feeler
gauge through so we just put in new points and re-did the timing.
>Once we did that, the idle AFR went from 11.5 to 13. Seems like the 
>advanced timing was messing up the MPS and the a/f mixture.
>
>I've yet to have a set of points go bad on me in only 1600 miles.
>Admittedly, I only have about 70,000 miles of VW driving under my belt 
>but still..Part of me wonders if repeatedly having the key in the 
>ignition in the on position while toggling the fuel pump prime switch 
>hastened the death of these points. Maybe I can power the switch from 
>an always hot fuse and see what happens?
>
>
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Don Robertson - (905) 566-0000
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