TACH-TEST  ... the handy shop tool

Every workshop needs one of these....  a simple tester to determine if a tachometer is functional and reasonably accurate.  Surprisingly, many older tachometers are inaccurate and this little tool will quickly expose them for what they are!

TACH-TEST - $100 plus shipping

TACH-TEST is simple to use.  Just connect it to a 12V source (for example, the vehicle battery) and connect the 3 other leads (power ground and signal) to your tachometer. Very useful for checking functionality and accuracy of the tachometer as well as troubleshooting signal continuity through the vehicle wiring to the tach.  

Switch selectable, this unit works with most 4, 6 and 8-cylinder tachs. For rpms, the rotary switch selects zero, 500, and 1000 to 10000 rpm in 1K steps with an accuracy of a few %.  An output switch lets you choose between a low and high-level trigger signal. An LED indicates output activity.

The unit comes with a 6-foot power cord and 3-foot output leads, all with insulated alligator clips to make attachment to 12V power and the Tach quick and easy. The output "LO" position, provides a current limited 12V rectangular wave to the tach.  In the "HI" position that signal is enhanced with a 150V 'spike' to trigger older points/coil-triggered tachs.  These low-energy signals will not damage your tach. Unit is reverse-battery protected and short-circuit protected.

Other Products and Services by AshlockTech


The “Speed Relay” comes in a few versions for early Porsche depending on whether the car had Carburetors (911T and certain 912 models) or MFI (911 E,S).  This device is found on the engine electric panel. It monitors engine speed and on closed/trailing throttle situations it cuts off the fuel supply until the rpms drop under approximately 1700.  This conserves fuel, improves emissions and serves to reduce exhaust “popping”. The most common problem with these units is component failures due to vibration and corrosion resulting in mechanical failure of the component leads.  It is not uncommon to shake these units and actually hear parts rattling around loose inside!

Send your unit into me and I will clean it up, repair and replace components as needed and fully test it.  

Repair Cost is $99 plus shipping.

TWIN-SPARK  Inductive Ignition Modules:

Developed for high performance twin spark plug Porsche 912 engines, (and similar applications) this product solves the problem of spark synchronization.  Precise physical manipulation to equally match the gap and positioning of two sets of distributor points is no longer necessary. This unit synchronously drives two isolated Coils (1.5 to 3-Ohm) from a single ignition signal (one distributor points or common points-eliminator module) eliminating timing differences of the ignition event. Each coil gets full current.  $199 plus shipping

A high-energy version of the Twin-Spark Module is also available.  This unit uses adaptive dwell control to drive coils with resistance as low as 0.5 Ohms without excessive coil current at low rpms.  Low resistance, low inductance H.E.I. coils provide a longer, high energy spark duration and allow larger plug gaps for firing lean mixtures. $299 plus shipping. 


Developed for Tachometer rebuilders, this postage-stamp size PC-Board module replaces the old electronics in vintage VDO (as well as many other) tachometers.  Especially useful for replacing failed electronics, converting Tachometers for different engine cylinder counts, or re-purposing a Tach with a new face and expanded display range.  For example, converting a 4-cyl, 7K rpm Tach to a 6-cyl 10K rpm Tach. 

This module accepts high level (~150V) signals from traditional points/coil ignition as well as discrete low-level (5 – 14V) engine speed signals from modern engine management systems.  The unit outputs a linear rpm/voltage that can be scaled to drive various analog meter movements commonly found in most tachometers.  (This unit is not for stepper-motor movements.)  This module is available in single quantity for $39, or in jobber lots of 10 pieces for $300.

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