Hey - did you know if you click on the title of a thread it will take you to the first unread post since you last visited that thread?
but were afraid to ask: 
STOP!! Never post your email address in open forums. Bots can "harvest" your email! If you must share your email use a Private Message or use the 
smilie in place of the real @
Pretty Please - add it to our Events forum(s) and add to the calendar! >> 
I have a problem with my '72 B burning out points & condensers way too often. Last set's lifespan was about 2300 miles. I don' suppose changing them this often would be too much of a problem, but the engine runs great, until suddenly (and usually on a back road 5 miles from anywhere) they give up the ghost, catching me by suprise every time... Though I did have half the police force comming to check out the car and chat yesterday while I waited for a tow truck... Anyway, the distributor is OE, and the coil is from Advance & still good. Would a worn out distributor do this? Or do I need to look elsewhere? I'm planning to re-wire it all B4 I get it running, since the parts won't be in until friday anyway. If anyone knows a good online spot for this it would be welcome also.
-
Hi Guest!
You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
There are some perks with a member upgrade!**Upgrade Now**
(PS: Subscribers don't see this gawd-aweful banner
Ignition Blues
- Thread starter edothas
- Start date
Share this page
CraigFL
Jedi Trainee
Offline
I don't have my shop manual here to check but I believe your car should have a resistor in series with the coil. Normal action is to bypass this resistor when trying to start so that the spark is hotter. Regular running requires the resistor to be in series to cut down on the current that the points have to switch. Sounds like you need to verify that you have this resistor.
Hello Edothas,
that should not happen. Is the coil the correct type, i.e. a ballasted coil being used in a non ballast system? A worn distributor won't be the cause but ensure the movable point is free and not stiff on the spindle. Points should last 10 to 15,000 miles easily and condensers forever (unless you are very unlucky)
Alec
that should not happen. Is the coil the correct type, i.e. a ballasted coil being used in a non ballast system? A worn distributor won't be the cause but ensure the movable point is free and not stiff on the spindle. Points should last 10 to 15,000 miles easily and condensers forever (unless you are very unlucky)
Alec
Thanks for the quick replies! Now for a dumb question... I'm terrible with electrical, so can I get directions on how to check if the coil spark is strong enough?
I just got through swapping & resetting the points (old ones looked prety new) and rotor button, but will be waiting on the rest for a couple o' days. the resistor & cap look brand new as well, so I'm thinking it's really the coil. Anyone have suggestions on a nice aftermarket coil that won't stress that 34 amp alternator? Thanks again, all.
I just got through swapping & resetting the points (old ones looked prety new) and rotor button, but will be waiting on the rest for a couple o' days. the resistor & cap look brand new as well, so I'm thinking it's really the coil. Anyone have suggestions on a nice aftermarket coil that won't stress that 34 amp alternator? Thanks again, all.
Offline
Ignition coils come in two general varities.
The coil for use with a ballast has around 1.5 Ohms primary resistance (between the two small terminals). The wiring should be set up so that full battery voltage goes to the coil during starting only, & around 8 volts is fed to he coil via the ballast resistor when the starter is released.
The coil for use without a ballast has around 3 Ohms primary resistance. The wiring is set up to supply full battery voltage to the coil during start & run.
I believe that the B's used a 3 Ohm coil without ballast. If a ballasted type (1.5 Ohm) coil is used without a ballast, the points will rapidly burn. Measure the resistance across the coil's two small terminals with an ACCURATE Ohmmeter.
If you have a coil intended for ballasted operation, 1.5 Ohms, it is possible that the ballast has been bypassed by wiring changes. With the ignition switch in the on position but not start, the voltage measured between the small coil terminal & ground should be around 8 volts with the points closed. If you have a non ballasted coil, the voltage should be about 12 volts.
If you don't have an accurate Ohmmeter, the running current through the points (switch in the run - not start position & points closed) should be no more than about 4 amps for either ballasted or non ballasted setups. Some "super coils" will draw more than the nominal 4 amps & point life will be considerably shortened.
D
The coil for use with a ballast has around 1.5 Ohms primary resistance (between the two small terminals). The wiring should be set up so that full battery voltage goes to the coil during starting only, & around 8 volts is fed to he coil via the ballast resistor when the starter is released.
The coil for use without a ballast has around 3 Ohms primary resistance. The wiring is set up to supply full battery voltage to the coil during start & run.
I believe that the B's used a 3 Ohm coil without ballast. If a ballasted type (1.5 Ohm) coil is used without a ballast, the points will rapidly burn. Measure the resistance across the coil's two small terminals with an ACCURATE Ohmmeter.
If you have a coil intended for ballasted operation, 1.5 Ohms, it is possible that the ballast has been bypassed by wiring changes. With the ignition switch in the on position but not start, the voltage measured between the small coil terminal & ground should be around 8 volts with the points closed. If you have a non ballasted coil, the voltage should be about 12 volts.
If you don't have an accurate Ohmmeter, the running current through the points (switch in the run - not start position & points closed) should be no more than about 4 amps for either ballasted or non ballasted setups. Some "super coils" will draw more than the nominal 4 amps & point life will be considerably shortened.
D
So lets see if I've gt this right... Assuming that my coil is bad (I haven't checked it yet); My specs say that the coil should have 3.1 to 3.5 ohms, but doesn't mention a resistor anywhere - this means non-resistor? So Moss non-specifically recommends the Crane ps20/40, which happens to ship with a resistor. Can I install this coil without resistor, or will the coil burn up without the resistor?
Offline
If your coil is rated at about 3 Ohms, there should be no resistor. This would be an original coil.
The Crane PS 20/40 coil is rated at 1.4 Ohms primary resistance & MUST be used with a ballast resistor. Just connect the coil plus the resistor in place of the existing coil.
A better coil might be the Pertronix # 40611 from https://www.lbcarco.com or other places. It has a primary resistance of about 3 Ohms for use without a ballast.
D
The Crane PS 20/40 coil is rated at 1.4 Ohms primary resistance & MUST be used with a ballast resistor. Just connect the coil plus the resistor in place of the existing coil.
A better coil might be the Pertronix # 40611 from https://www.lbcarco.com or other places. It has a primary resistance of about 3 Ohms for use without a ballast.
D
G
Guest
Guest
Guest
Offline
Your car doesn't have a ballast resistor. Mine is a '72 and doesn't have one. Therefore your present coil must be one that is for the ballast type like Dave said. Your coil is probably good, just the wrong type. No, do not hook up the coil you mentioned without the resistor or you will be right back in the same place you are now. Burning points.
If you don't want to mess with changing wireing, then the best thing to do is look for a coil with a 3.1 to 3.5 ohm primary and hook it up like you have it now.
Why don't you consider going back to the stock coil. Victoria British Limited has one for $19.95 P/N 8-285 They also have a Lucas Sport coil that doesn't need the resistor for $39.95 P/N 8-288
Bob
If you don't want to mess with changing wireing, then the best thing to do is look for a coil with a 3.1 to 3.5 ohm primary and hook it up like you have it now.
Why don't you consider going back to the stock coil. Victoria British Limited has one for $19.95 P/N 8-285 They also have a Lucas Sport coil that doesn't need the resistor for $39.95 P/N 8-288
Bob
Nice car mrbassman! Would you happen to have a picture of the vacuume hoses that go to & from your vapor cannister that you can post? I could use a clarification on what my manual says.
Thanks everyone for all the information. I had to sleep late to let my brain finish growing (!) but I'm off now to apply the new knowledge. Update soon...
Thanks everyone for all the information. I had to sleep late to let my brain finish growing (!) but I'm off now to apply the new knowledge. Update soon...
And the results are in... First, I replaced some wiring that looked old. The coil say 'for non resistor systems'; so far so good. Voltage across the coil leads is between 10 and 11, not sure if that's good enough. Resistance completely pegged my meter (Excessive resistance DOES mean bad circuit, right?), also, when I finished testing (about 10 minutes) the coil was too hot to touch, just from normal current running through it. So my conclusion would be the coil... Now if I can just find my reciept..
G
Guest
Guest
Guest
Offline
An ohm meter at full scale reads 0 ohms or no resistance. It should never be used with power on. Resistance should be checked with no wires hooked up and no voltage on.
No, I don't have a picture of my canister. Mine has been desmogged by the previous owner.
Bob
No, I don't have a picture of my canister. Mine has been desmogged by the previous owner.
Bob
Er, do I feel stoopid. Coil unhooked reads ~3 ohms and current is 12v through all circuits. When the points are open, should there still be current through the distributor? I had a crash course in voltage manipulation from a theoretical physicist last night, but he isn't too good with practical applications.. He says that the current cutoff through the coil isn't working, thus no spark. Does that make sense to anyone?
dklawson
Yoda
Offline
Not to contradict anything you learned from the physicist....
Consider the "voltage" to be the force pushing electricity through. "Current" is the amount of electricity flowing. When you measure voltage you are measuring "push" not "flow".
The points are the "switch" that cuts off flow of current through the coil. If you connect the volt meter across the low tension terminals of the coil with the ignition on, you'll get no voltage reading with the points open. When you close the points (like by stuffing a screwdriver between the contacts) your volt meter will show the "voltage drop" resulting from current flowing through the coil.
Consider the "voltage" to be the force pushing electricity through. "Current" is the amount of electricity flowing. When you measure voltage you are measuring "push" not "flow".
The points are the "switch" that cuts off flow of current through the coil. If you connect the volt meter across the low tension terminals of the coil with the ignition on, you'll get no voltage reading with the points open. When you close the points (like by stuffing a screwdriver between the contacts) your volt meter will show the "voltage drop" resulting from current flowing through the coil.