Distributor Modification?

The spring that holds the brush in my distributor cap was so corroded that it snapped the other day. Could the cause of this be trapped ozone gas within the cap? Would the cap benefit from having a ventilation hole drilled in it somewhere? Magneto caps on prewar Alvis had vents, so why don't the post war distributor caps?  Would drilling a hole risk ignition of petrol fumes? Is there some other means of distributor ventilation that I have missed?  If there is, why do the springs corrode? How can it be prevented?   Interested to hear all opinions on this please.  I've been chasing an intermittent misfire for yonks and the corroded spring is all that I have found to be wrong so far. Posted by Angus D'Arcy-Drake 29/06/2016 08:57:20

Angus,  I too have had rusty carbon brush springs in the cap. That said they were very old springs. I have looked at the fit between cap and distributor body (DVXH6) and there are some gaps and these were with original Lucas parts. Personally I wouldn't be fussed. I have had no issue with new brush and spring currently fitted to the TA21.   Richard Melbourne Posted by RichardWallach 29/06/2016 10:06:13

Re intermittent misfiring - I had this on the Sp25 for about 15 months. Eventually when it failed completely (M25 at night on way home from  France!), I found a loose terminal screw in the junction box behind the fuses on the bulkhead. Posted by DaveT 29/06/2016 11:32:41