After checking to make sure that the car had not skipped a link on the timing chain – it hadn’t – I took off the dist cap to be sure the rotor was pointing where it should and I was surprised to find that the centre contact was partially burned off! It was an economy rotor. The dark grey unit is the better quality unit (all CarQuest brands) They seem Identical.
There is a difference in the colour of the contacts. Not sure what the difference is. The old one looks to be bronze, but the new one???
I decided to replace the cap as well. The contact plates seem to be bronze where the old cap had Aluminum or stainless?
The plug posts are obviously the same as the undersides.
These are the centre contact electrodes the one on the right is the old one and it has a groove in it where the rotor contact strip was cutting its way through. Also, again brass vs aluminum or stainless.
On a good note, Carquest is refunding me for the rotor. I’m not going to gripe about the cap as I’ll keep it for a backup (that I should never need given the miles the Chevy will travel).