Vibration/ harmonics

[DaveJRH]

There are two types of analogue sync gauges. Magnetic pickup and W terminal pulse from alternator. As my tacho's are driven by the alternator the first thing to do is ensure that the alternator pulley's are an exact match. Volvo supply the pulley with the correct reduction for your tacko's so use that. While doing that calibrate your tacho's with a hand held rev counter although this is not essential for the sync it helps you co-ordinate the throttles to sync. Also important is to set throttle throws to be uniform and that both engines idle at the same speed. Again this is just to assist you. I personally find that when both throttles are exactly matched it does not fit my hand as I increase revs and prefer the stbd lever to lead slightly. Visually it also looks straighter then. A bit of a faff but worth the effort if you are going to be in sea states that require frequent throttle changes.
As for the W terminal tacho installation is super simple. Instrument lights is obvious, so is positive to ignition and negative. Then there are two W terminals port and starboard that piggy back onto each tacho W feed with a split connector. Very simple.
ASAP supplies do sell some gauges but they change periodically. I special ordered by vdo gauge from them and it had a 8 week lead time. Use is rather simple, balance the needle. This is where calibrating everything comes into play. If you did a good job you are almost always in sync anyway. Finally, I used to sync by ear like tuning a guitar. That works for higher revs like a charm. Lower revs harmonics I was surprised to find were quite off from my ear. Because the % difference in revs is inversely logarithmic the instrument is quite sensitive to low revs and so easier to finely tune as the needle moves more.

Thanks for the information Bruce.
My tacho's are driven by a rotary switches from the camshaft so I shall take a feed from those
Dave

 

[BruceK]

Magnetic sensor? If so ASAP have one in stock, but if you look through their catalogue could find one more suited to your existing cluster

Faria Beede Competition Square Synchroniser, Magnetic Pick up 5"



Faria Synchroniser Gauge - Google Search

 

[Greg2]

Thanks for the information Bruce.
My tacho's are driven by a rotary switches from the camshaft so I shall take a feed from those
Dave

+1
Many thanks for the info, very helpful. In all my years of boating I wasn’t aware that such analogue kit existed! ?
.