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Sync Gauge + Tachs

bulletine

bulletine

Regular Contributor
Now my alternator problem is fixed, I want to figure out how to get the sync gauge and tachs in agreement. I have been reading as much info as i could find and there is not much I can use at this point. Most posters to other forums state they rely on the sync gauge and not the tachs. I have been doing the opposite, relying on the tachs. My Sync gauge is always bouncing around.

So I would like to see what you all think about which gauges to rely on. Also, what is the best way to adjust these gauges so they read the same, or at least close. A example is when I get the sync gauge in the right position (12:00) my port engine is about 800 RPMs higher than the other engine at 2000 RPM.

Both engines idle well at 670 RPMs and run really well all the way to WOT. I would like to have the engines running in the most economical way as I have not yet installed Floscans, it may be a while before I can purchase them.

What is the best method for adjusting all the gauges?

Thanks
 
I sync by the sound of the engines using the tachs to get me in the ballpark. Once you know what to listen for its easy. Your tachs may have an adjustment on the back. Connect both tachs to the same engine with a jumper & play with the adjustment on one until they match. The sync is probably adjusted in a similar fashion. The installation manual will have the procedure.
 
Thanks. If there is an install/adjustment procedure, I have not been able to find it. I checked several forums and the VDO website. I believe this is a common problem and hopefully someone will be able to explain the adjustment procedure. Most of the forums I read state the tachs are usually not accurate, I assume the pulse frequency received by the sync gauge comes from the tachs, if this is true, then the inaccuracy is compounded, correct? I do not know...

If I rely on sound, this is not the most accurate method, especially with gas prices pushing $5.14 a gallon. Besides, I prefer to have everything functioning as well as possible on my boat.

Perhaps there is no easy solution. If there is, I am sure I will learn about it here.
 
My "ear" sync for some reason does not work with my boat. What does work is a couple of digital flowscans with the tach feature built in. Don't need the sync meter with those.
 
The Garmin chartplotter and network system we use now provides us with sync information but we use one main display only ($$$$)...switching around to the correct screen is not that hard but it does take more than a few button presses and you lose the chart you are reading. It is very easy to look up on the dash and watch the 3" sync gauge. At low speeds it does bounce around but gives you the information to sync engines even at a low 800 rpm. At higher cruise speeds, it is easy to tap a throttle up or down and match 'em up. You can hear the beat frequency at some intervals but not all. I like the sync gauge. Check the Faria site as their tech/spec sheets and install guides are avialable as PDF's. You may just find some similarities. However, those fuel flow meters of any type REALLY open up your eyes and provide some useful data.
 
My ear does not work either. I had preselected a Floscan - Twinscan a few months ago, but now the selection may not have been right. Do you have the [FONT=Verdana, Arial][FONT=Verdana, Arial][FONT=Verdana, Arial]7000 Multifunction Meter [/FONT][/FONT][/FONT]model with the tach? If so, it appears to be a much better choice.
 
Yes, I have two of the 7000's. They fit in the previous tach holes perfectly. You do need a couple of little momentary push button switches to reset each totalizer.
 
Most of the run-of-the-mill tachs will NOT have any adjustment feature...and I haven't seen a User adjustable 'zero' on a sync gauge yet.

Every sync gauge I've seen, on a gas engine, will work independently of the tach, assuming the tach is good.

Best way to assess everything is to use an optical tach as a reference. One note, based on past experience, if things were 'working fine' and a sudden 'disagreement' occurs, you may want to look of a fouled plug or damaged spark plug lead.

I use the gauges to get things close and then use the ears and tune the beat frequency as low as possible.
 
As Mark says...the optical tach is really a nice option for accuracy. At idle, I have a little fun with it but at cruise, ain't no way I'm hanging out that close to the engine and a little piece of reflective tape. Did it once and it was a VERY smooth day and still scary.
 
I have a digital tach that clamps on to any wire and I have been using that. The optical tachs seem to be less expensive and I will think about adding one to my bag of tools, I like tools...

So far, I have reduced the variance from around 800 RPMS down to 200 (between the sync gauge and tachs), I have more work to do today. I want a accurate reading and now I see progress I am going to clean both distributors and terminals. What I discovered so far is 95% of my problems are with the terminals, the wiring is good but corrosion had gotten to the ends of the wires, it is a 22 year old boat. The good thing is Tiara did a great job in wiring and labeling via the wiring diagrams.
 
I have a friend with a very nice $$$ optical tach and we compared my cheap one to the good one.....VERY LITTLE Difference
 
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