Greg’s Engine & Machine

Car Year, Make, Model: Tuning carb with a vacuum gauge Hook up your vacuum guage to the intake manifold port of the carb sucks at idle. Set you rpm about where you want it to be. Adjust your idle mixture screws to give you the highest manifold vacuum reading which should be the highest idle rpm reading with the throttle butterflies closed. Re-set your idle rpm. Run it a while and read your spark plugs.


How do I hook up my tachometer? Standard Ignition Coil If you have a standard ignition coil you can use the negative terminal of the coil for the signal source. If you have a high output capacitive energy discharge type coil it is recommended that you install a tachometer filter to prevent damage to the tachometer. Ignition Box If you have an ignition box i. If you have a 5V Tachometer signal you can: Install a ohm “pull up” resister from the 12V gauge power source ACC to the signal wire to increase the signal strength.

short answer, yes. long answer, it depends – the vane is a resistor (or sometimes two) that is switched. the anemometer and rain gauge are just switches.

Fuel control system Other parts affecting the combustion process emission devices, etc. Each has a characteristic effect on vacuum and you judge their performance by watching variations from normal. It is important to judge engine performance by the general location and action of the needle on a vacuum gauge, rather than just by a vacuum reading. Gauge readings that may be found are as follows: Normal Engine Operation At idling speed, an engine at sea level should show a steady vacuum reading between 17″ and 21″ HG.

A quick opening and closing of the throttle should cause vacuum to drop below 5″ then rebound to 21″ or more. General Ignition Troubles Or Sticking Valves With the engine idling, continued fluctuation of 1 to 2 inches may indicate an ignition problem. Check the spark plugs, spark plug gap, primary ignition circuit, high tension cables, distributor cap or ignition coil.

Fluctuations of 3 to 4 inches may be sticking valves. Intake System Leakage, Valve Timing, Or Low Compression Vacuum readings at idle much lower than normal can indicate leakage through intake manifold gaskets, manifold-to-carburetor gaskets, vacuum brakes or the vacuum modulator. Low readings could also be very late valve timing or worn piston rings. Exhaust Back Pressure Starting with the engine at idle, slowly increase engine speed to 3, RPM, engine vacuum should be equal to or higher than idle vacuum at 3, RPM.

How to Wire an Electronic Tachometer as Easy as 1-2-3

Installation Instructions A tachometer is a good addition to any vehicle equipped with a manual transmission. Installation of the Autogage Tachometer was fairly simple with only minor wiring including a wire to the distributor, a good ground, a 12 volt switched power source and a wire to power the tach’s light. The following write-up is an overview of the installation I followed and includes a few illustrations from the installation guide provided from Autogage.

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I love my Chevy Chevette! I rebuilt my cluster and had came across a deal on another cluster to use for parts. As I was putting the new one together I decided to use the tach off the 2nd cluster but did so without knowing if it worked or not – I was told it did but it sure looked far better. My problem is this tach does work but it seems to be high on the RPM side – K and when the car is shut off the needle drifts up to about 15K and sits there until the car is started again where my original would drop to zero when I shut the car off.

Is the needle drifting ok or a sign of a problem? How can I verify the tach is accurate or calibrate it?


A Magneto is a generator which generates alternating current AC , a normal automobile system uses direct current DC. These two demons affect the newer model of tachometers. Most manufacturers now use a different type of instrument than the ones they used years ago. Which seemed to work well. Now that you know what the problem is, what can you do about it?

Now that you have assembled, tested, and installed your MegaSquirt, you need to get your engine started and tuned. This is not too difficult if you work methodically, and do not let your enthusiasm prod you into a premature full-throttle melt-down.

Many later models use a “directly coupled” tachometer. I can’t provide any information about those since I’ve never owned or worked with one. There is an existing light and power sub-harness that connects two lights to this segment of the instrument panel and provides power to the factory clock or tachometer when installed.

The BLUE wire is not switched by design. This existing wiring should work perfectly. I used it instead and everything worked perfectly.


We have a Plymouth Valiant that we want to use in double duty on the street as a cruiser, and at the track as a bruiser. There is a lot at stake here—namely a hp low-deck Chrysler big-block stuffed with a lot of high-quality parts. The only real thing to decide with an Auto Meter tachometer is what features you want, what size you need, and what cosmetics you like.

It also comes with basic mounting hardware to strap it to your steering column, dashpad, or instrument panel. Models are also available for in-dash mounting without the cup or base.

The rear of the package states that it is 20 gauge wire; however, looking closely at the markings/text printed on the wire, it is clearly labeled as 22 gauge (reason for 4 stars).

It has a lot of the same great features as the Shop Fox: You also get a bit more room to work. It tilts within the same 55 degree range. That extra versatility is thanks to its extended frame design, which provides all the capacity of a riser block but with greater structure and rigidity. We recommend this one to DIYers who are ambitious, and want to work with larger planks.

It cuts extremely well. This one has a slightly more powerful motor than the Shop Fox, and you can feel the difference:

Whats up with a jittery RPM needle?

The CRB Hand Wrapper features a dual spool tensioner and a tension rod which allows for easy reversing while building. Thread then runs to the slider which can move seamlessly along the 10″ wrapping base. The wrapper also features adjustable stands mounted to the base along with a third stand for supporting the butt or tip. Finally, the hand wrapper incorporates interchangeable step by step instruction cards displaying a range of basic wrapping and advanced decorative techniques, and the basic wrapping Step by Step card is included.

The CRB Rod Dryer offers rod builders a durable, easy to use drying unit that is perfect for novice and professionals, at a price point unheard of in the industry without sacrificing functionality.

This tachometer has wires that are too short by half, and was easy to hook up once I added several feet of wiring to attach it to. This thing registers over rev right off the bat.

It turns tighter and it’s much more stable at top speed! The widened sponson improves cornering, handling and high speed stability. Machined from billet aluminum and black anodized for corrosion resistance. Drive from turn to turn never worrying whether the trim is in the best position for perfect turn negotiation! The 5 degree positive angle lightens the nose of the craft and adds top speed; this is great for recreational use.

Both types are available in bore sizes of mm. Custom bore sizes from 80 to 90 available at no extra charge, specify size when ordering. The nozzle also offers 4 extra bosses that can be drilled and tapped for extra cooling fittings. Removing this restriction significantly reduces cavitation and improves holeshot and hook up with any prop type or diameter. Service turnaround time is days. These precision couplers are made from billet aircraft aluminum and CNC machined to exact tolerance. The exclusive lightweight filter design couples to the OEM throttle body through a tuned built in velocity stack.

The engineered oversized Tear Drop plenum, delivers the velocity and cubic air volume needed to add power.

How To Install a Tacho Gauge