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Adjusting new tachometers
Posted: May 3rd, '11, 20:30
by Mack
Finishing up my dash panel/guage replacement project, however I am waiting for two backordered guages. In the meantime, we have installed the other guages and have done a massive "clean up" of wiring. Finally was able to run the engines the other day but realized that I hadn't yet set the tachs for the correct number of impulses.
The tachs are new VDO "viewline", which require you to set three switches in the rear of the guage depending on the number of impulses per rotation of your engine. I have mercruser 454's but have no idea what number of impulses I need to set the tachs to.
Before I get on the horn to VDO tech support, thought I would check here to see if someone knows.
Posted: May 3rd, '11, 20:46
by In Memory of Vicroy
Call VDO, they always have been helpful to me. My 6BTA Cummins use the VDO magnetic flywheel pickup and you have to set the DIP switches on the back of the tack for the # of flywheel teeth....my tachs came with a data sheet for various engines and flywheel tooth counts. Yours either count the frequency of the AC output of the alternator or the pulses from the electronic ignition.
Trivia of the day: 6BTAs have 159 flywheel teeth.
UV
Posted: May 3rd, '11, 21:27
by JohnD
Mack,
See if this is what you need...2nd pg diagram C.
http://www.egauges.com/pdf/vdo/0-515-012-020.pdf
If not here's the link to more setup info
http://www.egauges.com/Inst_PDF.asp
br,
JohnD
Posted: May 4th, '11, 14:05
by Harry Babb
Vic wrote:Trivia of the day: 6BTAs have 159 flywheel teeth
I owe you a beer Vic....or the beverage of your choice.....I forgot to count teeefees on the flywheel before reassembly....saved me from the mark a tooth, screw driver thru the hole and counting routine...
Besides, it would take 15.9 of us rednecks to count to 159
hb
Posted: May 6th, '11, 13:34
by Mack
Yes, the instructions I have are similar to what John D posted, however the 3 positions of the "DIP" switches depends on how many pulses per revolution the engine it producing. I am told by mechanic that Merc 454 (and most) gas engines do not run a tach off the flywheel. It is done off the alternator or ingnition coil.
I spent some time on the phone with VDO tech support, only to come up with the answer "call mercruiser."
Anyone how many times a 454 will fire to pruduce one revolution? I assume that is the number I need if the tach is connected to the ingnition.