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Need help hooking up your Ford tach, go here and print it: www.instrumentsrus.com/fordhkp.htm
Some Helpful Information From Instrumentsrus On Testing Your Classic Car Instruments!
CHECKING YOUR MUSTANG/FORD IN LINE TACHOMETER!
WARNING: NEVER ALLOW YOUR TACHOMETER TO GET AROUND METAL PARTICLES ON A DIRTY WORK BENCH!  THE METER MOVEMENT WILL GET CONTAMINATED, CAUSING THE NEEDLE TO STICK.
MUSTANG/FORD TACHOMETERS (MOST 1963-76 FORD, 1965-73 MUSTANG) CAN CAUSE YOUR ENGINE NOT TO START.  THE 12 VOLTS TO THE PLUS SIDE OF THE COIL GOES THROUGH THE TACHOMETER ELECTRONIC CIRCUIT THAT CONTAINS A SPECIAL INPUT ISOLATION TRANSFORMER.  IF THE PRIMARY OF THE TRANSFORMER IS BURNED UP OR OPEN NO VOLTAGE AND THE RESULTING CURRENT FLOW WILL GET TO THE PLUS SIDE OF THE COIL.  THEREFORE YOUR ENGINE WILL NOT START.  THE CIRCUIT ON THE BLACK WIRE SIDE OF THE TACH GOING TO THE COIL ALSO CONTAINS A CALIBRATED BALLAST RESISTANCE BEFORE IT GETS TO THE PLUS SIDE OF THE COIL.  THIS CALIBRATED RESISTANCE WIRE IS 1.5 OHMS.  THE BALLAST RESISTANCE WIRE IS MADE OF TUNGSTEN TO WITH STAND HEAT.  NEVER CUT THIS WIRE AS IT CAN'T BE RESTORED IN ANY WAY.   THE BEST WAY TO CHECK THIS IS TO INSTALL A KNOWN GOOD TACHOMETER AND SEE IF THE ENGINE WILL START.  ANOTHER WAY IS TO FIND A GOOD VOLT-OHM METER AND SELECT THE OHMS R TIMES 1 SCALE AND MEASURE ACROSS THE 2 LEADS COMING OUT OF THE TACH.  IF THE METER READS OPEN OR NO RESISTANCE AT ALL, THEN THE TACH'S INTERNAL ELECTRONIC CIRCUIT IS DEFECTIVE.  IF THE TACH LEADS READ AROUND 1 OHM OR SO AND THE CAR STARTS, BUT THE TACH STILL DOES NOT WORK, THEN THE TACH METER OR ELECTRONIC CIRCUIT STILL NEEDS REPAIR.  IF YOU NEED TO SEND YOUR TACH TO US FOR REPAIR, YOU CAN REMOVE THE MALE AND FEMALE BANANA PLUGS FROM YOUR TACH LEADS AND JUMPER THEM TOGETHER.  THE ENGINE WILL RUN WITH THE TACH OUT OF THE CIRCUIT WHILE IT IS BEING SERVICED.   SINCE INSTRUMENTSRUS IS AUTHORIZED FORD/MUSTANG SERVICE, WE CAN REPAIR THESE TACH'S QUICKLY AND AT AN AFFORDABLE PRICE.  NEVER ALLOW ANY INSTRUMENT REPAIR SHOP TO CONVERT YOUR FORD/MUSTANG TACH TO THE MINUS SIDE OF THE COIL AS SERIOUS DAMAGE WILL OCCUR.  EMAIL US ATinfo@instrumentsrus.comAND WE WILL REPAIR YOUR FORD TACHOMETER.  ANY PARTS INSTALLED BY INSTRUMENTSRUS CARRY A 2 YEAR WARRANTY!
UNDERSTANDING BALLAST RESISTANCE
A BALLAST RESISTOR IS ACTUALLY A CURRENT LIMITING DEVICE THAT HAS A VOLTAGE DROP.  EVEN THOUGH WITH THE CAR RUNNING, YOUR ALTERNATOR IS PUTTING OUT AROUND 13.8 VOLTS, THE VOLTAGE ACTUALLY GETTING TO THE PLUS SIDE OF THE COIL IS AROUND 8-10 VOLTS.  WHY? BECAUSE WE ARE USING A DC CURRENT HERE AND IF NO BALLAST RESISTOR IS IN THE CIRCUIT TO THE COIL YOUR ENGINE WILL START RUNNING VERY ROUGH IN ABOUT 30 SECONDS.  THE COIL MAY FRY AND THE ELECTRONIC CIRCUIT IN THE FORD/MUSTANG IN LINE TACH WILL START SMOKING VERY QUICKLY.  A/C (ALTERNATING CURRENT) VOLTAGE IS A SINUSOIDAL WAVE FORM THAT GOES ABOVE AND BELOW THE 0 TIME LINE AXIS.  WHEN THE SINE WAVE GOES PLUS 180 DEGREES HEAT IS GENERATED AND WHEN THE SINE WAVE GOES 180 DEGREES BELOW THE 0 AXIS LINE A COOLING PROCESS OCCURS.  WITH DC OR DIRECT CURRENT THIS DOES NOT HAPPEN, THUS THE NEED FOR A BALLAST RESISTOR. WHETHER IT'S FORD/MUSTANG THAT CONNECTS TO THE PLUS SIDE OF THE COIL OR GM/MOPAR THAT CONNECTS TO THE MINUS SIDE OF THE COIL.  A BALLAST RESISTOR MUST BE USED BECAUSE IT LIMITS CURRENT WHICH PRODUCES THE AFOREMENTIONED VOLTAGE DROP SO YOUR COIL DOES NOT HEAT UP AND YOUR ENGINE RUNS CORRECTLY.

NOTE: SINCE A FORD/MUSTANG TACHOMETER IS IN LINE WITH THE PLUS SIDE OF THE COIL, DOUBLING THE BALLAST RESISTANCE, 3 OHMS PER SAY, WILL MAKE THE TACH READ HALF.  IF YOU ARE EXPERIENCING THIS SITUATION WITH YOUR FORD/MUSTANG TACHOMETER READING HALF, CHECK TO MAKE SURE YOU ONLY HAVE 1.5 OHMS OF BALLAST RESISTANCE!

NOTE 2: EARLY AMC TACHOMETERS OPERATE ON THE SAME PRINCIPLE AS DESCRIBED ABOVE.

  
1963 UP FORD, MOPAR AND GENERAL MOTORS SPEEDOMETER CHECKOUT!
FIRST, THIS WARNING:  NEVER ALLOW YOUR SPEEDOMETER TO GET AROUND ANY METAL PARTICLES ON A DIRTY WORK BENCH.  SPEEDOMETERS HAVE MAGNETS AND WHEN AROUND ANY METAL PARTICLES THEY WILL GET INTO THE COIL MAGNET ASSEMBLY CAUSING ERRATIC SPEEDOMETER OPERATION! VERY FRUSTRATING PROBLEM.

NOW, LET'S TROUBLE SHOOT YOUR SPEEDOMETER.  YOU WILL NEED A REVERSIBLE DRILL (0-2800 R.P.M DRILL IS THE BEST) BECAUSE SPEEDOMETERS TURN COUNTER CLOCKWISE.  THERE CAN BE SEVERAL PROBLEMS WITH A CLASSIC CAR SPEEDOMETER.  THE CABLE, THE SPEEDOMETER AND THE GEAR IN THE TRANSMISSION, WHETHER AN AUTOMATIC OR MANUAL.  TAKE THE CABLE LOOSE FROM THE TRANSMISSION AND CHUCK IT UP TO THE REVERSIBLE DRILL AND HAVE A FRIEND SIT IN THE CAR.  POWER UP THE DRILL AND IF THE SPEEDOMETER JUMPS AROUND AND IS UNSTABLE, THE PROBLEM COULD BE THE CABLE OR THE SPEEDOMETER.  REPLACE THE CABLE AND IF PROBLEM STILL EXISTS, THE SPEEDOMETER COULD BE THE PROBLEM. TO VERIFY THIS YOU WILL NEED TO PULL THE DASH, REMOVE THE SPEEDOMETER ( YOU WILL NEED TO CUT OFF AN OLD SPEEDO CABLE INSERT END) CHUCK THE END IN THE DRILL AND SEE IF THE SPEEDOMETER IS ERRATIC.  IF NOT, IT IS THE CABLE OR THE GEAR IN YOUR TRANSMISSION.  IF THE SPEEDOMETER IS ERRATIC WITH THE DRILL MOTOR ATTACHED TO IT OUT OF THE CAR, THE PROBLEM IS THE SPEEDOMETER.  YOU CAN THEN SEND THE DEFECTIVE
SPEEDOMETER TO INSTRUMENTSRUS.  EMAIL US ATinfo@instrumentsrus.com WITH ANY REPAIR QUESTIONS!

NOTE: 1970-74 MOPAR E BODY CLASSIC CARS ARE NOTORIOUS ABOUT DEFECTIVE GEARS IN THE TRANSMISSION CAUSING APPARENT SPEEDOMETER PROBLEMS!

 
CHECKING FORD AND MOPAR TEMP, FUEL AND OIL PRESSURE GAUGES
DURING THE CLASSIC CAR ERA FORD AND MOPAR GAUGES WHERE PRODUCED USING NI-CHROME WIRE WINDINGS INSIDE THE GAUGE THAT WOULD CAUSE 2 TERMINALS TO EXPAND OR CONTRACT DURING THE GAUGE MONITORING PROCESS.  THERE IS ONE BASIC WAY TO CHECK THESE GAUGES.  HOWEVER, THIS METHOD IS ONLY ABOUT 90 PERCENT ACCURATE.  GET A GOOD VOLT OHM METER AND SWITCH TO THE R TIMES 1 SCALE AND ATTACH YOUR LEADS TO THE 2 STUDS COMING OUT OF THE GAUGE.  IT SHOULD READ AROUND 1O OHMS, PLUS OR MINUS AND MOST LIKELY THE GAUGE  IS GOOD.  HOWEVER, THIS METHOD IS NINETY PERCENT ACCURATE . OTHER FACTORS INCLUDE THE SHAPE OF THE NI-CHROME WIRE WINDINGS IN THE GAUGE ITSELF.  ALTERNATOR GAUGES IN FORD AND MOPAR USE A DIFFERENT SETUP AND CAN BE CHECKED BY APPLYING A LARGE D.C. POWER SUPPLY ACROSS THE 2 REAR TERMINALS.  WHEN APPLYING 12 OR 13.8 VOLTS ACROSS THE ALT GAUGES 2 REAR TERMINALS (JUST TAP IT OR YOUR TEST LEADS MAY START TO SMOKE:) THE POINTER SHOULD JUMP AND THE ALT GAUGE IS MOST LIKELY GOOD.  INSTRUMENTSRUS CAN REPAIR AND CALIBRATE MOST OF THESE GAUGES WITH A 2 YEAR WARRANTY!  WE CAN ALSO PROVIDE A FREE EVALUATION OF YOUR GAUGES TO MAKE SURE THEY ARE OPERATING PROPERLY.

NOTE: MOPAR AND FORD GAUGES WILL DROP BACK TO THE LOW SIDE OF THE GAUGE WHEN POWER IS TURNED OFF.

CHECKING GENERAL MOTORS GAUGES
CORVETTE, CHEVELLE, CAMARO, NOVA, IMPALA, BUICK, OLDSMOBILE, G.M. TRUCKS
G.M. GAUGES (INCLUDES MOST CORVETTES) FROM 1965 UP ARE BASICALLY THE SAME AND ARE ENTIRELY DIFFERENT THAN FORD OR MOPAR GAUGES. THE BIG DIFFERENCE IS G.M. GAUGES DO NOT RETURN TO LOW OR ZERO WHEN THE ENGINE IS TURNED OFF.   G.M. TEMP, FUEL AND ELECTRIC OIL GAUGES USE 3 OR 4 POLES PROTRUDING FROM THE BACK AND A CALIBRATION RESISTOR THAT MAY BE WIRE WOUND OR A WHITE CERAMIC SLAB WITH DIFFERENT COLORS.  IN ORDER TO CHECK THESE GAUGES YOU MUST FIND OUT WHERE THE 12 VOLT, SENDING UNIT AND GROUND POLES ARE.  THESE VARY GREATLY FROM YEAR TO YEAR. WHEN YOU LOCATE THEM, GET A GOOD 12 VOLT POWER SUPPLY.  THEN PUT THE PLUS 12 VOLT LEAD FROM THE POWER SUPPLY TO THE GAUGES 12 VOLT TERMINAL.  APPLY THE GROUND LEAD TO GROUND AND THE GAUGE SHOULD MOVE ONE WAY.  THEN TAKE THE GROUND LEAD AND APPLY IT TO THE LEAD WHERE THE SENDING UNIT COMES IN AND THE GAUGE SHOULD MOVE THE OTHER WAY. IF THERE IS NO MOVEMENT THEN THE GAUGE IS NO GOOD.

G.M. AMP OR BATTERY GAUGES: UNLIKE FORD OR MOPAR AMP, ALTERNATOR OR BATTERY GAUGES, G.M. AMP/BATTERY GAUGES ONLY SAMPLE CURRENT USING A PARALLEL VICE SERIES CIRCUIT TO INDICATE AMP.  THE BEST WAY TO CHECK THESE GAUGES IS TOO USE A VOLT OHM METER AND USE THE R TIMES 1 SCALE AND CONNECT THE METER LEADS ACROSS THE 2 TERMINALS ON THE BACK.  IF THE GAUGE IS GOOD YOU SHOULD READ AROUND .5 OHMS. THIS GOOD READING IS ONLY 90 PERCENT ACCURATE AS THE COIL WINDINGS ENAMEL COATING COULD BE DETERIORATING AND THUS NEED REPAIR  IF YOU GET NO READING THEN THE WINDINGS ARE BURNED UP IN THE GAUGE AND IT NEEDS REWOUND.  EMAIL US ATinfo@instrumentsrus.com AND WE WILL REPAIR AND CALIBRATE YOUR GAUGES WITH A 2 YEAR WARRANTY.  NOTE: MANY GM ELECTRICAL GAUGES LOSE THEIR DAMPENING.  IF THE NEEDLE ON YOUR TEMP, FUEL, AMP OR ELECTRIC OIL GAUGES CAN BE SPUN AROUND EASILY THEN IT HAS LOST IT'S DAMPENING FLUID.  INSTRUMENTSRUS HAS A SPECIAL TOOL THAT CAN RESTORE DAMPENING AND MAKE YOU GAUGE LIKE NEW!


THERE IS NO SAFE WAY TO INSTRUCT YOU ON HOW TO CHECK MOPAR, G.M., SUN, OR CORVETTE MECHANICAL/ELECTRICAL TACHOMETERS.  THE BEST WAY IS SEND YOUR TACHOMETER TO US FOR A FREE EVALUATION.  WE CAN UPDATE THESE TACHS TO MODERN ELECTRONICS AND CONVERT CORVETTE MECHANICAL TACHS TO ELECTRONIC!
MOPAR 1968-1974 TACH LEAD HOOK UP!
THE ABOVE PICTURE SHOWS HOW TO PROPERLY ATTACH YOUR 12 VOLT IGNITION AND COIL PICKUP LEADS ON A 1968- 1974  MOPAR TACHOMETER.  THE SILVER STUD IS 12 VOLTS IGNITION AND THE COPPER LEAD (MOST LIKELY WILL HAVE A WIRE CLIP ON IT AS PICTURED) GOES TO THE MINUS SIDE OF THE COIL OR TACH SENDER.  FAILURE TO HOOK THESE WIRES UP CORRECTLY WILL BLOW A FUSE IN MY SOLID STATE  REPLACEMENT BOARD PICTURED ON THE MOPAR PAGE.  I ALWAYS ATTACH A LABEL TO ALL TACHS WE SERVICE THAT WILL MAKE SURE YOUR TACH LEADS ARE CONNECTED PROPERLY!
 INSTRUMENTSRUS HAS STATE OF THE ART TACHOMETER, SPEEDOMETER AND GAUGE CALIBRATION EQUIPMENT THAT INSURES YOUR INSTRUMENTS ARE PROPERLY CALIBRATED.  SATISFACTION GUARANTEED!
 
I SINCERELY HOPE THIS PAGE WILL HELP ALL CLASSIC CAR ENTHUSIASTS THAT WANT TO TROUBLESHOOT THEIR CLASSIC CAR INSTRUMENTS.  IF YOU HAVE ANY QUESTIONS OR NEED SERVICE YOU KNOW WHO TO CALL, INSTRUMENTSRUS.   CALL 1-864-895-4404 M-F 10-5 EST
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