Here is the deal: I have an 87 IROC TPI that I converted to speed density and also used the external coil distributor. I swapped the stock coil out for the Mallory Promaster. I also have the mallory HyFire IV ignition box. Anyway, sometimes the Autometer tach I have does not work. I have good ground, 12V, and the light on the tach has a good connection. This has lead me to the tach terminal at the HyFire box being bad. I want to verify this by splicing into the factory tach wire. I was told on another post that I should splice into the brown wire on the distributor but there is not a brown wire on any of the distributor connections. The wires coming of the distributor are tan/black, black/red, white, pink, and yellow. The wiring manual I have says that the white wire is the tach wire to the instrument cluster but I thought that this wire was for the EST connection at the ECM. Which one is the tach wire?????????? Could I also connect the tach feed to the coil ground with the HEI ignition or does this only work with standard ignitions. Thanks for your help. I'm at my wit's end.
BSA

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"If they do not run, Then they will die." - Stonewall Jackson
#3
'87 IROC, 355 TPI, Converted to SD, 700R4, B&M Megashifter, 3.42, Trick Flow Twisted Wedge Heads, Edelbrock Intake, Accel Runners, Comp Cam, Crane Gold rockers, Lucas 23# injectors, Edelbrock headers, Flowmaster 3'' exhaust, Mallory Ignition, Transgo Performance Shift Kit, Corvette Servo, 2,000 Stall Torque Converter