TeamFatAss's Bonneville lakester (open wheeled special construction) has a pretty vanilla set up: carburated 383" SBC crate motor + TH350
MSD Streetfire HEI distributor + Racepak IQ3 monitoring the usual stuff.
We don't really need all the data we collect, but i just like knowing what's going on.

By having good grounds and moving sensor cables away from ign wires, all channels are mostly clean.

All except RPM... It's useable (when the scale is exaggerated) but i'm not happy with it.
My race bikes had clean RPM signals from AIMSport & DL-32 systems, so i expect our lakester to have a clean RPM trace.

The MSD dist cap has a "Tach" port which we are using.
We've tried a shielded/grounded tach cable = no change.
Also tried MSD's GMR inductive pickup (PN 8918) = no change
Talked to both MSD & Racepak tech people = very friendly & helpful but no change yet

Next step is to mount an MSD Digital Ignition Control (PN 6425) which MSD tech says should cure our RPM blues AND it's give us a rev limiter. I wouln't stress over this issue if i didn't have an extra year to get ready for 2016 Bonneville.
I'm guessing that it's me doing my normal dumb azero stuff, but i'm determined to solve this.

Does anyone "out there" have an MSD + Racepak set up? Experience?
Karl in Houston