[Rich P]

I'm after some help with my tacho. I've read various threads about this but am still unclear.
I have a 1974 Targa. I recently did an ignition tune up and changed the plugs/ plug wires/ distributer cap and arm/ and a new MSD blaster coil. the only part of the maintenance kit I didn't use was the new points I also did a service with fuel filter/ fuel accumulator (due to a hot start issue)/ oil filter and oil change. I used Wayne Dempsey's excellent 101 projects book for this work.

Everything fired up well on the first few runs but the Tachometer has developed wild swinging during acceleration. At idle it will settle at around the 1000rpm mark.

This was fine prior to me carrying out this work. I can't figure out why. I've checked around the engine where I was working and can't see anything loose.

It would seem that something must have happened during this work- it would be a bit coincidental if the alternator had suddenly failed 10 miles after this work. I'm a little suspicious of the new coil- it's the only part that has been switched in (I did ask at Pelican if it was compatible prior to purchase). Could this new coil have fried something/ caused an issue. I put the old coil back and the problem is still there.

Any thoughts would be gratefully accepted.

Thanks