tachometer installation

Status
Not open for further replies.
E

Ed A

.
Sep 27, 2008
333
Hunter 37c Tampa
Im trying to install a tach on a yanmar 3 gm
the tack has been set up for a 4jhe.
does anyone know the settings for the new tach to make it read properly?
there are three settings on a switch and a small pot to adjust for a fine tune. Im not sure who made the tach, Just thought i would make it a little harder for ya?

Ed
 
kloudie1

kloudie1

.
Nov 6, 2006
10,104
Hunter 34 Mandeville Louisiana
Interesting.. Thanks for the link, Ed S.
I may end up putting an alternator based tach on my old 3 GMF.. The original 3 GM tachs counted flywheel teeth; 97 per rev..
 
Ed Schenck

Ed Schenck

.
Jun 2, 2004
5,802
Hunter 37-cutter, '79 41 23' 30"N 82 33' 20"W--------Huron, OH
Makes me wonder. Could Ed A's orignal 4JH been mechanical? I thought because he mentioned a switch that it was electrical. Maybe not.
 
kloudie1

kloudie1

.
Nov 6, 2006
10,104
Hunter 34 Mandeville Louisiana
I think you are right, Ed.. The new one is an alternator driven one because of the switch that he mentions The "tooth counters" have a number in the bottom of the tach face and no switches. He probably will have to run new wires to get the alternator signal, since the old wires may go to the pick-up on the flywheel of the 3 GM.. depends on modifications over the years.. always interesting !
 
Marc14857

Marc14857

.
Jun 5, 2004
485
Hunter 44 Mystic, Ct
Ed

My H44 had a Yanmar (VDO) tachometer set up for a 4JH4E engine. Unfortunately the tachometer was set up for an alternator that had 12 poles but my alternator which was the high amp option had 14 poles. As such the tachometer always read high. There is an adjustment on the back of the tach that let's you adjust either the actual RPM that you can read with a handheld tachometer or adjust for the number of poles on your alternator. You should be able to find the manual by googling VDO Gauges. If you can't find it let me know and I should be able to email it to you.
 
E

Ed A

.
Sep 27, 2008
333
Hunter 37c Tampa
AS usual i did not leave enough data. The 3 gm tach runs off the fly wheel. so does the aftermarket tach. but it does not say what setting to use. Only that it was set up at the factory for a 4jhe. This tack has a switch that has different ohm settings (3) choices, and an adjustment hole to tweek it to the exact rpm. It dances arround once in a while and reads a min of about 1000 rpm at idle and about 4300 when at top speed. I dont think the engine is going that fast on either end.
 
kloudie1

kloudie1

.
Nov 6, 2006
10,104
Hunter 34 Mandeville Louisiana
The original 4 jhe has a 127 tooth flywheel gear. The 3GM probably has a 97 tooth flywheel gear..so if set for the 4 JHE and functioning on the 3 GM, it should read OK, but low RPM by about 25% .. Have you got a manufacturer and model number for the tach, Ed ?
 
Last edited:
E

Ed A

.
Sep 27, 2008
333
Hunter 37c Tampa
no i dont have the mfg of the tach. i agree with the teeth issue.
I will try harder to findout more about the tach.

Thanks guys
 
E

Ed A

.
Sep 27, 2008
333
Hunter 37c Tampa
OK i finally got the right info.
I have a seaward tach, it is the correct tack and all i should have to do is turn the switch to corrolate with the number of teeth on the flywheel and i should be in the ballpark, then fine tune it with the adjustment control.

All that being said i have a bad new tach. oh well stuff happens so i will get that out and back soon and be going

Thanks for the ideas guys.

Ed
 
Status
Not open for further replies.

Top Bottom