Mid America Motorworks 602-781 Instruction Sheet

Application: Corvette 1978-1982
Tachometer Circuit Board Rebuild Kit
Tools Needed
STEP 1.
Removing the odometer set knob is the most difficult step in this process. With
a pocket screwdriver, press firmly on plastic tang as shown in Diagram A. Wiggle
knob free from stem.
STEP 2.
Remove three small Phillips screws from top of Speedo/Tach lens and one from
each side (Diagram B).
STEP 3.
Remove lens.
STEP 4.
Remove six Allen head screws that hold the face plate over the speedo/tach and
remove (Diagram C).
STEP 5.
Remove three screws that hold Tach housing. Remove tach by pulling unit from
housing.
STEP 6.
With tach laying face down on clean surface, remove three nuts (Diagram D)
that hold printed board to tach and remove defective board.
STEP 7.
Install new board. Replace three nuts. Install tach unit in tach housing.
STEP 8.
Start engine and check tach.
STEP 9.
If properly adjusted, tach needle should rest at normal idle (around 1000 rpm).
If tach needle rests at higher than normal idle, needle is out of adjustment.
Shut engine off to adjust needle.
STEP 10.
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INSTRUCTION SHEET
Part Number
602-781
Part Includes
1 - Tach Board Replacement
3 - Flat Washers
Dash & Center Console
Bottom side of trip knob
DIAGRAM A
Lens Screw Location
DIAGRAM B
Tang