Series 3 24v FFR 12v coil lack of power under load

I have recently bought a 24v FFR series 3 that has been fitted with a 12v coil, standard 12v distributor, leads and plugs. I've noticed that under load going, going up hills the engine really lacks power.

I understand that the little black box "filter unit" sat on the rocker cover before the ignition coil drops the voltage down to 10v, so is imagine the 12v coil isn't giving as strong a spark as the original 10v coil did.

Can anyone advise what the cheapest way to rectify this is; can I get a 10v coil with standard connections, can I replace the "filter unit" for something that drops the voltage to 12v rather than 10v?

Any help would be greatly appreciated.

Look on craddocks site under military 24v ignition you might get 10v coil does distributor have rev limiter on it? 101 24v does and it uses filter\voltage dropper box and 10v coil

Thanks for the reply. I've had a look and I can get the standard 10v coil, but that is compatible with the shielded leads that have screwed connections. I have a big standard 12v distributor with the normal connections, not the screwed shielded type, hence why I was looking for a 10v coil with normal connections, not the screwed ones

The filter box only produces 10v at the coil when the points are closed. This is dependant on the resistance of the coil it has been designed for drawing the prescribed current to obtain this voltage drop. The filter box is a two-stage ballast resistor with some fancy filtering, it is not a regulator or a "transformer".

Actually one element of the ballast resistor increases in resistance with time & the actual voltage out then is more like 9v. I would avoid using some sort of regulator to provide 12v, the point about the ballast resistor is that it loads the primary circuit with resistance that off sets some of the effect of inductance & so reduces the time constant of the circuit. This was an important boost to the HT to offset some of the effect of the capacitance of the screened HT system gets "charged up" by the HT. This issue & using a 12v coil is covered in this description of the screened system:
http://hmvf.co.uk/topic/34113-bright-sparks-latest-update/

What are the screwed connections like? Are they like the gland nut type? If so you can put a washer on the HT lead and splay the inner strands through it then clamp that up. You can make up a lead with differnt ends to make an adapter.