The Ford Barn

Brian Philpott · 07-24-2010, 12:23 PM

I fitted a modern points/condenser plate on my car a few years back. In the last year I've had the classic symptoms of condenser failure on three occasions- misfire/backfire and loss of sparks. In each case I found burnt points and a blown main fuse. All the failures occurred within a half mile of start up. A roadside change of the points and condenser fixed the problems. I thought condenser failure as the cause! It seems I was wrong! As a precaution I had fitted a replacement 6v coil before today's failure.
After the latest breakdown I put a "failed" condenser back on the car today and it ran perfectly. Examination of the points shows not just burning but massive overheating. The moving contact is discoloured for .25 inch back from the tip with a straw to blue band indicating that it has probably been RED hot. The plastic part that forms the cam follower had started to melt where it contacts the moving contact arm.
It appears that I've been getting the full 6 volts in a dead short across the points which was in effect bypassing the primary winding of the coil.
Is there any way the red line from the CB/popout side of the coil can pick up 6volts? Has anyone had experience of intermittent shorting of this wire or a similar overheating of points?
Thanks for staying with this long tale!
Brian Philpott Camberley UK

Rainmaker Ron · 07-24-2010, 12:29 PM

I will guess that you are using a generator and that somewhere in the circuit, Probably on the back of the ammeter, you have a poor connection. This will cause the generator to produce high voltage, probably aroung 40 volts. This is what is cooking your points.

Rainmaker Ron

Rainmaker Ron · 07-24-2010, 12:31 PM

test number two

V4F · 07-24-2010, 12:33 PM

ron ,
im having a simular problem with modern points/condenser . using an alternator . they do not quit me , so far , but burn & cause short life . i change them b 4 they quit . any ideas please ..................... steve

Brian Philpott · 07-24-2010, 03:00 PM

Thanks for the input Ron. What I can't figure out is why the fuse is blowing as it's on the battery side of the ammeter and buffered by battery capacity and shouldn't see the runaway genny voltage.
However, you have got me thinking. Maybe the fuse blowing is a cause not an effect. If the fuse blew for some reason on engine start, the ignition circuit would see the high voltage and it would also explain why all the failures have occurred a half mile from setting off. Of course, it still leaves me with the problem of finding why the fuse is blowing.
What do you think?

skip · 07-24-2010, 11:31 PM

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Let me preface my remarks by saying, "Beats me."

With a modern upper plate and 1970 Ford V-8 points on the upper plate and with a modern condenser screwed onto that upper plate than I'm thinking several things.

1~That the electroplated hard face of tungsten on each surface of the points is either no good and burning off. Whole batches of new points have been trashed by the factory or dealerships because they simply won't pass juice.
~Or as suggested above loose connections and too many volts going through the points. I really don't know.
~For me with distributor in hand and a continuity meter hooked up to the dist body ground and the points, I make sure the points 'make' and 'break' reliably.
~If you have a bad condenser I'm not sure that you'll pass enough juice through the points to the coil to make a spark.

2~The problem could be that the lower plate and screwed in armored jacked ignition cable that touches the lower plate detent...and that 'touch' energizes the whole electrically isolated lower plate and wire powering the points above on the upper plate may be shorting out with a little induced heat movement. Things grow when they get hot.

~Now there really is no need for the 'tang' that hangs down on the isolated lower plate that contains the detent for the screwed in armored jacket and ignition cable if your not running the old style condenser.
~You could cut that tang off if it's shorting out inside the distributor. And then use the mounting hole used for the old style condenser as a bolting area for a new ignition wire without the armored jacket that will power up the points. Essentially you 'Hot Wire' the ignition without a pop out mechanism or armored jacket.

3~Just a passing thought. A little PVC electric tape around the bottom of the dist cap to 'firm-up' the dist cap to dist body fit may help. And a tad of paper under the rotor to firm that up may take a little wiggle out of the rotor fit above the point cam.

It's the very little things that get over looked that make a good day a bad day. skip.

Rainmaker Ron · 07-25-2010, 12:16 AM

Quote:

Originally Posted by Brian Philpott

Thanks for the input Ron. What I can't figure out is why the fuse is blowing as it's on the battery side of the ammeter and buffered by battery capacity and shouldn't see the runaway genny voltage.
However, you have got me thinking. Maybe the fuse blowing is a cause not an effect. If the fuse blew for some reason on engine start, the ignition circuit would see the high voltage and it would also explain why all the failures have occurred a half mile from setting off. Of course, it still leaves me with the problem of finding why the fuse is blowing.
What do you think?

Tuff one, maybe a shorted stop light or whatever. Could be something blows fuse soon after start-up. We had one like that, short in stop light. Put new fuse in, start and drive away...car was fine as long as it was kept above idle(running on generator) when it did die the fuse was found blown. There are not that many co9nnections, just recheck all for tight and clean. I would disconnect the light harness feed during a daytime run and and see if the fuse still pops. Goood hunting.
Rainmaker Ron

Rainmaker Ron · 07-25-2010, 12:24 AM

Quote:

Originally Posted by steve norcal

ron ,
im having a simular problem with modern points/condenser . using an alternator . they do not quit me , so far , but burn & cause short life . i change them b 4 they quit . any ideas please ..................... steve

Steve, 6 or 12 volt? If you are running on 12 volts or have installed an unknown coil on 6 volts, check the resistance across the coil circuit including resister if used. Shoot for 1 to 1.5 ohm on 6 volts and 2 to 3 ohms on 12 volts.

Rainmaker Ron

Ron in Quincy · 07-25-2010, 12:58 AM

You might also check your stop light switch leads; one of the club members would drive his A about a mile and the A would die, he found a blown fuse. In checking out his problem found the stop light switch lead to the tail light was grounded. When he steped on the brake and activated the switch he would blow the fuse.

MikeK · 07-25-2010, 08:44 AM

Quote:

Originally Posted by Brian Philpott

. . . .Is there any way the red line from the CB/popout side of the coil can pick up 6volts? Has anyone had experience of intermittent shorting of this wire or a similar overheating of points?
Brian Philpott Camberley UK

Brian, YES!
Check for worn through spots on the continuous red lead from the coil to the popout where it loops through the firewall terminal box to get to the popout connection stud. It may be intermittently shorting to either of the terminal studs in the box. Both studs are always 6 volts. You may want to pull and replace that one entire wire.

V4F · 07-25-2010, 09:07 AM

Steve, 6 or 12 volt?
sorry ron , 6v system . thank you , ill check it today ................. steve

Brian Philpott · 07-25-2010, 03:13 PM

Gentlemen
Thank you all for your comprehensive inputs. I've been at the All Ford Rally today so haven't been able to pursue further wiring checks. I'll do that tomorrow and, if I don't find any damaged wires or loose connections, I'll give the ign circuit its own fused supply straight off the battery and put an indicator light across the fuse so I can catch the moment that it blows.
Watch this space!!!

Bruce Lancaster · 07-26-2010, 10:35 AM

Add in a dedicated ground, a wire from a screw on point plate to bat ground cable. That way you have the entire electrical path substituted out and can remove either substitute side or change its attachment point until you induce the trouble.

Brian Philpott · 07-26-2010, 04:40 PM

I did an end-to-end check of the wiring today and only found one small cut in the horn hot line insulation that was not in a location that could have grounded and caused the fuse to blow. All wiring between the terminal block and dash was fine with nothing loose. Also found stoplights blown as a result of runaway voltage. Dedicated wiring to coil is now fitted together with 36v. dash lamp across fuse to highlight fuse failure. I'll now just drive it and see what happens. Many thanks for all your suggestions

Purdy Swoft · 07-26-2010, 04:56 PM

Problems with battery cables can cause runaway voltage spikes. I had a problem with one of those battery cable end disconect devices. It may be worth the trouble of cleaning and tightening your battery cables.

Benson · 07-26-2010, 05:42 PM

Brian,

If the car has or had in the past an electric wiper or dome light there is a black and blue wire that goes from one side of terminal box up through the passenger side windshield post to the wiper and or dome light.

I have seen these short out near the thumb wheel nut that tightens the windshield when you "turn on the air conditioner".

Maybe just disconnect the wire at the terminal box for while.

cars56 · 08-09-2010, 01:02 PM

Atttended a club clinic recently.
Matching the coil to the condenser and points was brought up.
Wish I knew how to do it.

Patrick L. · 08-10-2010, 04:07 PM

Well, the coil is easy.. Decide whether to use 6v or 12v and hook them it the same as the battery.. In other words if battery + is ground then coil + primary lead eventually should end up at the points.. If using 12v coil then you need to know if its a resistor coil coil or not.. If it is then you're good to go.. If not, then you need an external resistor.. As far the condenser goes, its pretty easy today. You purchase the set and they should be matched.. If there is a problem with point pitting then a different capacity condenser is needed depending on how/where the pitting occurs[ stationary or movable arm and whether you're looking at the stalactite or stalagmite ].. You can either move up or down in capacity after measuring the condenser you have.. I forget which way to go though without looking it up..

07-24-2010, 12:23 PM	#1
Brian Philpott Junior Member Join Date: May 2010 Posts: 8	Repetitive Points Burn out I fitted a modern points/condenser plate on my car a few years back. In the last year I've had the classic symptoms of condenser failure on three occasions- misfire/backfire and loss of sparks. In each case I found burnt points and a blown main fuse. All the failures occurred within a half mile of start up. A roadside change of the points and condenser fixed the problems. I thought condenser failure as the cause! It seems I was wrong! As a precaution I had fitted a replacement 6v coil before today's failure. After the latest breakdown I put a "failed" condenser back on the car today and it ran perfectly. Examination of the points shows not just burning but massive overheating. The moving contact is discoloured for .25 inch back from the tip with a straw to blue band indicating that it has probably been RED hot. The plastic part that forms the cam follower had started to melt where it contacts the moving contact arm. It appears that I've been getting the full 6 volts in a dead short across the points which was in effect bypassing the primary winding of the coil. Is there any way the red line from the CB/popout side of the coil can pick up 6volts? Has anyone had experience of intermittent shorting of this wire or a similar overheating of points? Thanks for staying with this long tale! Brian Philpott Camberley UK

07-24-2010, 12:29 PM	#2
Rainmaker Ron Senior Member Join Date: May 2010 Location: Peoria IL Posts: 282	Re: Repetitive Points Burn out I will guess that you are using a generator and that somewhere in the circuit, Probably on the back of the ammeter, you have a poor connection. This will cause the generator to produce high voltage, probably aroung 40 volts. This is what is cooking your points. Rainmaker Ron

07-24-2010, 12:31 PM	#3
Rainmaker Ron Senior Member Join Date: May 2010 Location: Peoria IL Posts: 282	Re: Repetitive Points Burn out test number two

07-24-2010, 12:33 PM	#4
V4F Senior Member Join Date: May 2010 Location: ca. Posts: 2,522	Re: Repetitive Points Burn out ron , im having a simular problem with modern points/condenser . using an alternator . they do not quit me , so far , but burn & cause short life . i change them b 4 they quit . any ideas please ..................... steve __________________ V4f

07-24-2010, 03:00 PM	#5
Brian Philpott Junior Member Join Date: May 2010 Posts: 8	Re: Repetitive Points Burn out Thanks for the input Ron. What I can't figure out is why the fuse is blowing as it's on the battery side of the ammeter and buffered by battery capacity and shouldn't see the runaway genny voltage. However, you have got me thinking. Maybe the fuse blowing is a cause not an effect. If the fuse blew for some reason on engine start, the ignition circuit would see the high voltage and it would also explain why all the failures have occurred a half mile from setting off. Of course, it still leaves me with the problem of finding why the fuse is blowing. What do you think?

07-24-2010, 11:31 PM	#6
skip Banned Join Date: May 2010 Location: Sturgeon Bay, Wisconsin Posts: 408	Re: Repetitive Points Burn out Sponsored Links (Register now to hide all advertisements) Let me preface my remarks by saying, "Beats me." With a modern upper plate and 1970 Ford V-8 points on the upper plate and with a modern condenser screwed onto that upper plate than I'm thinking several things. 1~That the electroplated hard face of tungsten on each surface of the points is either no good and burning off. Whole batches of new points have been trashed by the factory or dealerships because they simply won't pass juice. ~Or as suggested above loose connections and too many volts going through the points. I really don't know. ~For me with distributor in hand and a continuity meter hooked up to the dist body ground and the points, I make sure the points 'make' and 'break' reliably. ~If you have a bad condenser I'm not sure that you'll pass enough juice through the points to the coil to make a spark. 2~The problem could be that the lower plate and screwed in armored jacked ignition cable that touches the lower plate detent...and that 'touch' energizes the whole electrically isolated lower plate and wire powering the points above on the upper plate may be shorting out with a little induced heat movement. Things grow when they get hot. ~Now there really is no need for the 'tang' that hangs down on the isolated lower plate that contains the detent for the screwed in armored jacket and ignition cable if your not running the old style condenser. ~You could cut that tang off if it's shorting out inside the distributor. And then use the mounting hole used for the old style condenser as a bolting area for a new ignition wire without the armored jacket that will power up the points. Essentially you 'Hot Wire' the ignition without a pop out mechanism or armored jacket. 3~Just a passing thought. A little PVC electric tape around the bottom of the dist cap to 'firm-up' the dist cap to dist body fit may help. And a tad of paper under the rotor to firm that up may take a little wiggle out of the rotor fit above the point cam. It's the very little things that get over looked that make a good day a bad day. skip. Last edited by skip; 07-24-2010 at 11:40 PM.

07-25-2010, 12:58 AM	#9
Ron in Quincy Senior Member Join Date: May 2010 Location: Quincy, CA. Posts: 1,708	Re: Repetitive Points Burn out You might also check your stop light switch leads; one of the club members would drive his A about a mile and the A would die, he found a blown fuse. In checking out his problem found the stop light switch lead to the tail light was grounded. When he steped on the brake and activated the switch he would blow the fuse.

07-25-2010, 09:07 AM	#11
V4F Senior Member Join Date: May 2010 Location: ca. Posts: 2,522	Re: Repetitive Points Burn out Steve, 6 or 12 volt? sorry ron , 6v system . thank you , ill check it today ................. steve __________________ V4f

07-25-2010, 03:13 PM	#12
Brian Philpott Junior Member Join Date: May 2010 Posts: 8	Re: Repetitive Points Burn out Gentlemen Thank you all for your comprehensive inputs. I've been at the All Ford Rally today so haven't been able to pursue further wiring checks. I'll do that tomorrow and, if I don't find any damaged wires or loose connections, I'll give the ign circuit its own fused supply straight off the battery and put an indicator light across the fuse so I can catch the moment that it blows. Watch this space!!!

07-26-2010, 10:35 AM	#13
Bruce Lancaster Member Emeritus Join Date: May 2010 Location: Madison, NJ Posts: 5,230	Re: Repetitive Points Burn out Add in a dedicated ground, a wire from a screw on point plate to bat ground cable. That way you have the entire electrical path substituted out and can remove either substitute side or change its attachment point until you induce the trouble.

07-26-2010, 04:40 PM	#14
Brian Philpott Junior Member Join Date: May 2010 Posts: 8	Re: Repetitive Points Burn out I did an end-to-end check of the wiring today and only found one small cut in the horn hot line insulation that was not in a location that could have grounded and caused the fuse to blow. All wiring between the terminal block and dash was fine with nothing loose. Also found stoplights blown as a result of runaway voltage. Dedicated wiring to coil is now fitted together with 36v. dash lamp across fuse to highlight fuse failure. I'll now just drive it and see what happens. Many thanks for all your suggestions

07-26-2010, 04:56 PM	#15
Purdy Swoft Senior Member Join Date: May 2010 Location: Alabama Posts: 8,099	Re: Repetitive Points Burn out Problems with battery cables can cause runaway voltage spikes. I had a problem with one of those battery cable end disconect devices. It may be worth the trouble of cleaning and tightening your battery cables.

07-26-2010, 05:42 PM	#16
Benson Senior Member Join Date: May 2010 Posts: 2,594	Re: Repetitive Points Burn out Brian, If the car has or had in the past an electric wiper or dome light there is a black and blue wire that goes from one side of terminal box up through the passenger side windshield post to the wiper and or dome light. I have seen these short out near the thumb wheel nut that tightens the windshield when you "turn on the air conditioner". Maybe just disconnect the wire at the terminal box for while.

08-09-2010, 01:02 PM	#17
cars56 Senior Member Join Date: Jun 2010 Location: Queens, NYC Posts: 212	Re: Repetitive Points Burn out Atttended a club clinic recently. Matching the coil to the condenser and points was brought up. Wish I knew how to do it.

08-10-2010, 04:07 PM	#18
Patrick L. Senior Member Join Date: May 2010 Location: Largo Florida Posts: 7,225	Re: Repetitive Points Burn out Well, the coil is easy.. Decide whether to use 6v or 12v and hook them it the same as the battery.. In other words if battery + is ground then coil + primary lead eventually should end up at the points.. If using 12v coil then you need to know if its a resistor coil coil or not.. If it is then you're good to go.. If not, then you need an external resistor.. As far the condenser goes, its pretty easy today. You purchase the set and they should be matched.. If there is a problem with point pitting then a different capacity condenser is needed depending on how/where the pitting occurs[ stationary or movable arm and whether you're looking at the stalactite or stalagmite ].. You can either move up or down in capacity after measuring the condenser you have.. I forget which way to go though without looking it up..