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Gentlemen, I've read every thread I could find and have called MSD tech support. Now I'm coming to the experts for advice. Sorry for the long explanation and question.
On my 302 engine rebuild for my 83 F100 I installed the Holley Sniper EFI with Holley HyperSpark Ignition, HyperSpark Coil, and HyperSpark Distributor. Everything works great and so far loving it.... I salvaged a dash cluster years ago from a truck that had a tach and a trip meter that my cluster didn't have. I installed blue LED dash lights and painted the needles as recommended in other threads and installed the salvaged dash cluster. It looks great. Problem... the tach didn't work. Contacted Holley and they said I needed a tach adapter which they gladly sold me. Installed it and tach now works except the tach value is double what it should be. More research and I've concluded that I probably bought a dash cluster from a vehicle with a tach that was made for a waste spark ignition, Ford EDIS. If this is the case I would think the tach value would be half not double? Has anyone ran into this problem?
With a factory tach is there a way to set the number of pulses per revolution? Is there a converter I could purchase that would correct the problem or is there a tach from another model that would work?
On the factory tach, there is a way to set it if it's a six cylinder engine or a 8 cylinder. There is a jumper somewhere I believe, I will have to try and research what it is, some of the other guys on here probably know. There was no EDIS ignitions during 80-86.
Dave, thanks for the info. I have it wired up as described with G and 8 grounded. Holley brown wire is attached to 1. I'll drop the ground from 8 and see what happens. Guess I should check to see if the MSD is sending a neg signal to the tach.
I have had the same issue but with MegaSquirt. The tach output of the sniper is likely 5V . There is a guy somewhere in Arkansas that make a small module that looks like a relay. It works great.
Ebay TACH TACHOMETER SIGNAL BOOSTER, 3~16V In -> 48~63V Out, compare to MSD 8920
