Smith Tack to MSD

[user509035]

who knows how to hook up Smith Tac to MSD ignition box. What adapter do I need. Just hooking up tac to box it works fine till you hit 3000 rpms then it falls to zero, any help will be appreciated

[FWB]

does this help you?

https://www.mpsracing.com/instructions/MSD/8920.pdf

the below link explains a adapter needed if tach doesn't work above 3000 rpm

http://www.erareplicas.com/427man/wiring/msd.htm

[Cobra #3170]

This could be wrong because I am operating from a memory of how the original Smiths tach worked but this is what I remember. There was a white wire that went through the tach and to the positive side of the coil. The tach picked up impulses from the wire (I think it had a couple of loops inside the tach). As I remember there was no physical electrical connection other than inductive. The Tack had power ground and lighting in addition to the inductive loop. I took mine apart and put Mustang tach guts in it because the Smiths had a big lag time. You might have a problem with an MSD because of the multiple pulses at lower rpm. MSD has a tach signal but it is not set up for an inductive pulse pick up. This information would be applicable to 1966-1968 cars newer tachs may be different.

[FWB]

couldn't tell you, just found that info, i run all SW gauges.
there is a post from 2003 here stating there are two types of smiths gauges,
one of which needs the adapter the other not