Well, it finally happened. I lost all spark today. So I caved and cracked the wallet for an MSD5 and Blaster2 coil. Fairly straightforward installation.

The only problem I have now is that my (aftermarket) tach needle is bouncing around 2K RPM at idle, but it smooths out and reads accurately (I think) once true RPM reaches about 2500.

Any suggestions?

 

Is the switch in the back set to the right engine type?

And when using the MSD box does that effect the switch in the back of the tach?

 

Is the tach hooked up to the tach lead on the MSD box or straight off the coil? If it is on the coil, it is reading the extra coil fires at low rpm and misinterpreting them thus giving the screwed up reading. As engine speed increases, the multi firing coil evens out and the tach gets a better signal to read. MSD provides a tach hook-up point just to eliminate this problem.

 

Near as I can tell, there's no tach port on the 5 series MSD.

 

How about the tach adapter mentioned on the bottom of page 3 and shown better on page 4?

http://www.msdignition.com/pdf/5200_frm18162.pdf

 

Yeah.....I saw that...but I was hoping to avoid it. Particularly since the truck is neither fuel injected nor a ford.