tach help 8v71

[4106-123]

im trying to install a tach on my 4106 is a isspro tach i need to know the pulses per revolution on the alternator. i have the signal wire conected to thr relay terminal on the 50dn the guy at isspro said it had to be a ac tap is the relay terminal a ac tap? thanks in advance

[Jerry Liebler]

The 'r' terminal is the signal you need to get to the tach.  The generator is a 6 pole device and the ratio on your engine is 2.29-1  So you should select 13.74 pulses/rev or whatever is closest to that.
Regards
Jerry 4107 1120

[RTS/Daytona]

Note 1 ->For Detroit Diesel Delco gear driven 50DN
            270 Amp 24 volt alternators "R" Terminal hookup
            The "R" terminal output is 12 volt -
            Most 6V92TA's are: (2.93 gears & 6 pulses per Revolution=17.58 pulses/rev)
            Older 6V92's can be(2.75 gears & 6 pulses per revolution=16.5  pulses/rev)
            Older 8V71's can be(2.29 gears & 6 pulses per revolution=13.74 pulses/rev)         

[TomC]

I used a pulse generator that was installed on the tach drive off the blower.  Good Luck, TomC