Volvo Tach Issue

[theprofessordan]

Is my tach wrong or properly calibrated???

I thought I was overrevving the engine and needed a different prop. I hooked up an engine tach and noticed that the boat tach is way higher than the analyzer.

I read the manual and found out the rear of the tach has several different settings for 2, 3,4, 5, and 6 pulse. I can find nothing on what this means.

Anyone know what the proper setting is for a 1997 Volve 5.7 GL 350 2bbl. Don't want to break my tach if I turn on the wrong setting.

Are boat tachs that far off??

Don S. are you out there??

 

[rodbolt]

Re: Volvo Tach Issue

who manufactured the TACH ?

 

[Don S]

Re: Volvo Tach Issue

Those don't sound like Volvo tach numbers, no 5 on the VP tachs.
If your tach looks like this on the back, then here are the numbers.
A= 4 cyl.
B= 6 cyl.
C= 8 cyl.

 

[havasuboatman]

Re: Volvo Tach Issue

If that isn't your tach, My first guess would be to put the selector on the number that corresponds with how many cylinders you have.
If there is no number 8, use number 4. then check it against your external tach.

 

[Fun Times]

Re: Volvo Tach Issue

Also I just helped someone eles out with about the same Question as you, And this is what he said he found wrong with his settings when I had him take a look.

I just checked the back of the tach. There are 6 settings. It says 1 = 4 cyls, 2 = 6 cyls, 3 = 8 cyls...etc. Mine is set to 2!(for 6 cyls) I guess that would explain the bad readings?

 

[theprofessordan]

Re: Volvo Tach Issue

The tach is the original tach for the boat. There are no A,B,C settings. Perhaps due to the 1997 year 5.7GL being an OMC engine that VP bought???

The setting on the back of the tach are 2,3,4, then 6,5 on a twist dial with an arrow. I tried turning the dial, there are no clicks or detents. Just put the arrow near the closest number.

Also says For 2,3,4 pul/rev alternators in sterndrive and 6 pul/rev OMC outboard sea engines

Part#75612 04-K-V Made in Mexico.

Does this help??? I don't believe the 2=4 cyl 3=6cyl, etc. I need to find out how may pulses per revs my alterntor is. Any idea how to do this?? Currently set at #4

VP #3856600 is the alternator.

My second choice is to get another tach and compare both to the boat tach.

FRUSTRATED!!!!!

 

[Don S]

Re: Volvo Tach Issue

Did you even look at the picture I posted ??????? No number 5. Turn the arrow to number 4. The letters with arrows are just pointing to the numbers.

Your pulses are NOT coming from the alternator, they come from the coil.

 

[earlandamys180]

Re: Volvo Tach Issue

I had the same issue on my boat my tach was showing some crazy rpm's on my 3.0 and it seems that over time the contacts build up some corrosion so if u will move the selector on the back of the tach a few times and put it back on the setting it is now it may help, it did on mine.

 

[JoLin]

Re: Volvo Tach Issue

I had the same issue on my boat my tach was showing some crazy rpm's on my 3.0 and it seems that over time the contacts build up some corrosion so if u will move the selector on the back of the tach a few times and put it back on the setting it is now it may help, it did on mine.

+1

I had exactly the same issue on my old outboard. Another poster here alerted me to it. Moved the selector back and forth a couple of times and put it back to the right setting. No more problems.

 

[havasuboatman]

Re: Volvo Tach Issue

Wish you had just replaced the tach yet?