Discussion
one for the RV8. Not a wedge but a RV8 Tiv all the same 
I could have a look at it in the garage if required to see if I can spot any identification marks 
. If you're looking for a recommendation, the Bosch PRC6574 (Land Rover part no) is the best bet. Sadly they now seem to have plain silver Aluminium cases instead of the satin Black they used to be.
You can get one from reputable suppliers such as ACT. BTW I have only ever seen one defective Bosch coil.
The MSD Blaster coils work very well too, but I have been unable to detect any significant difference on the dyno for EFI motors.
Either of these coils are of excellent quality.
There is another option, which is an Accel (USA) coil, available from Real Steel (Uxbridge). This gives a spark like an arc welder, and works especially well on carburetted race motors. The only challenge here is that IMHO it is UGLEEEEE!
It has a large square finned yellow plastic case with a brown top - good taste or what?
If you are looking at other coils, then the most important thing is that they are designed for Constant Energy ignition systems. This means they will have a primary resistance of around 0.5 to 0.8 Ohms.
You can get one from reputable suppliers such as ACT. BTW I have only ever seen one defective Bosch coil.
The MSD Blaster coils work very well too, but I have been unable to detect any significant difference on the dyno for EFI motors.
Either of these coils are of excellent quality.
There is another option, which is an Accel (USA) coil, available from Real Steel (Uxbridge). This gives a spark like an arc welder, and works especially well on carburetted race motors. The only challenge here is that IMHO it is UGLEEEEE!
It has a large square finned yellow plastic case with a brown top - good taste or what? If you are looking at other coils, then the most important thing is that they are designed for Constant Energy ignition systems. This means they will have a primary resistance of around 0.5 to 0.8 Ohms.
When I got some starting problems with the 400SE (hotwire) which turned out to be a dodgy wire connection, I also checked the coil. As far as I can see, the regular Lucas coil is fitted. The primary resistance turned out to be 3.0-3.3 Ohm and the secondary was about 5K. According to the wedge bible, it should yield 1.0-1.2 Ohm. 5K from the Lucas unit should be correct. As I understood, some like to replace them for the Bosch unit which yield about 8k.
The car starts fine, I don’t have any misfiring issue’s (cold nor hot), the coil does get hot, but not more than to be expected considering the environment where it’s living in. What are the consequences of a higher primary resistance? (or is there a measurement fault) I thought that cars without balance resistor required higher primary resistance?
The car starts fine, I don’t have any misfiring issue’s (cold nor hot), the coil does get hot, but not more than to be expected considering the environment where it’s living in. What are the consequences of a higher primary resistance? (or is there a measurement fault) I thought that cars without balance resistor required higher primary resistance?
There were two types as I recall, 6V ones must be used with a ballast resistor and 12V ones without.
The difference in primary resistance affects the amount of current that goes through the coil and therefore the energy in the spark when the current is interrupted by the points.
I would expect the 6V one to have a lower primary resistance than the 12V type, but whether that's a good means to identify them I don't know - better off using the part number on the coil.
I think the ballast resistor type fell by the wayside after battery and points technology improved, the original idea was that the solenoid disabled the resistor during cranking (e.g. on the Rover P5) and there would be a fatter spark off the 8 or 9V you would get across the battery.
The difference in primary resistance affects the amount of current that goes through the coil and therefore the energy in the spark when the current is interrupted by the points.
I would expect the 6V one to have a lower primary resistance than the 12V type, but whether that's a good means to identify them I don't know - better off using the part number on the coil.
I think the ballast resistor type fell by the wayside after battery and points technology improved, the original idea was that the solenoid disabled the resistor during cranking (e.g. on the Rover P5) and there would be a fatter spark off the 8 or 9V you would get across the battery.
Just managed to locate a Bosch PRC6574 .. Rimmer Bros quoted £137 .. have found http://www.johncraddockltd.co.uk selling them for £53 inc vat & delivery
Edited by JVaughan on Thursday 28th July 15:56
just gotta get HT leads and Plugs now ..... 
Not really - see my post a couple up... P5's used to have them but also had a third contact on the starter solenoid that shorted it out. The only point of this arrangement is to make the spark fatter during cranking.
If you installed one (and a 6V coil) I suppose you could add an extra starter relay to defeat it, but I've never had a problem with ignition during cranking on wedges, so it hardly seems worth the bother.
If you installed one (and a 6V coil) I suppose you could add an extra starter relay to defeat it, but I've never had a problem with ignition during cranking on wedges, so it hardly seems worth the bother.
Slightly off topic but quite relevant.
It's best to leave the small capacitor on the coil, it does aid in giving a better spark as well as reducing noise.
I watched an interesting YouTube video the explained the ins and outs of why, he had a setup with a scope also so you could see the difference. do a YouTube search if your interested.
It's best to leave the small capacitor on the coil, it does aid in giving a better spark as well as reducing noise.
I watched an interesting YouTube video the explained the ins and outs of why, he had a setup with a scope also so you could see the difference. do a YouTube search if your interested.
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