need4speed Posted June 26, 2015 Share Posted June 26, 2015 I'm fitting a 52mm VDO Vision tacho to my V8 and I'm getting some conflicting advice. It's regarding the 3 coding switches at the rear of the tacho. These are to trim the tacho for 4, 6, or 8 cylinders. Now I originally misplaced my fitting instructions within the hovel that passes as my garage. I called John at ETB Instruments to find out what position these switches need to be in for the V8. John very kindly replied to me saying that they all needed to be "on". Fair enough. However today I happened upon the fitting instructions and according to them it should be 1=on 2=on 3=off. What to do? Does anyone happen to have a VDO tacho in their V8? Quote Link to comment Share on other sites More sharing options...
Inigo Posted June 26, 2015 Share Posted June 26, 2015 I've got one, and I think I followed the instructions. I'll have a dig through my desk to see if I can find them and they match up with yours. Quote Link to comment Share on other sites More sharing options...
Inigo Posted June 26, 2015 Share Posted June 26, 2015 What do you know, I managed to find them - my instructions concur: on, on off. Quote Link to comment Share on other sites More sharing options...
need4speed Posted June 26, 2015 Author Share Posted June 26, 2015 Thanks Inigo. I will go with what the instructions say then. Especially as yours works. Quote Link to comment Share on other sites More sharing options...
western Posted June 27, 2015 Share Posted June 27, 2015 IIRC there's a adjusting screw on the side too, so you cab set the idle revs quite accurately. Quote Link to comment Share on other sites More sharing options...
need4speed Posted June 27, 2015 Author Share Posted June 27, 2015 Not sure what piece of equipment I'd need for that. Whatever it is you can bet I don't have it.. I'm presuming some kind of strobe. Quote Link to comment Share on other sites More sharing options...
western Posted June 27, 2015 Share Posted June 27, 2015 think you would need a strobe rev counter to get it accurate, but if you aim for a idle rpm around 750 to 850rpm on the gauge it won't be far off something like these which are rather expensive https://www.google.co.uk/webhp?sourceid=chrome-instant&rlz=1C1ASUC_enGB582GB582&ion=1&espv=2&ie=UTF-8#q=strobe+rev+counter&tbm=shop Quote Link to comment Share on other sites More sharing options...
Ex Member Posted June 27, 2015 Share Posted June 27, 2015 A laser tach is the easiest way to get it adjusted correctly. Cheap and good to have for the future. http://www.ebay.co.uk/itm/like/201276438867?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=108&chn=ps&device=c&rlsatarget=&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0-L&ff12=67&ff13=80&ff14=108 Instructions: http://static.summitracing.com/global/images/instructions/vdo-333158.pdf Quote Link to comment Share on other sites More sharing options...
need4speed Posted June 27, 2015 Author Share Posted June 27, 2015 A laser tach is the easiest way to get it adjusted correctly. Cheap and good to have for the future. http://www.ebay.co.uk/itm/like/201276438867?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=108&chn=ps&device=c&rlsatarget=&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0-L&ff12=67&ff13=80&ff14=108 Instructions: http://static.summitracing.com/global/images/instructions/vdo-333158.pdf Interesting. Can't seem to open the instructions link though Quote Link to comment Share on other sites More sharing options...
Landy-Novice Posted June 27, 2015 Share Posted June 27, 2015 Interesting. Can't seem to open the instructions link though http://static.summitracing.com/global/images/instructions/vdo-333158.pdf Quote Link to comment Share on other sites More sharing options...
Ex Member Posted June 27, 2015 Share Posted June 27, 2015 http://www.nsifleet.com/pdf/TachometerwithoutEngineHourMeter.pdf Quote Link to comment Share on other sites More sharing options...
dangerous doug Posted June 27, 2015 Share Posted June 27, 2015 I have a timing light with digi rpm read out from accuspark it was £45 posted. Really good and not bank busting Quote Link to comment Share on other sites More sharing options...
need4speed Posted June 27, 2015 Author Share Posted June 27, 2015 Thanks guys. Those links work fine. Looks like something else for the shopping list. Has anyone that has used one found their VDO tacho to be out by much? Quote Link to comment Share on other sites More sharing options...
=jon= Posted June 28, 2015 Share Posted June 28, 2015 How are you driving it - from the alternator or from an ignition pulse? The dip switches are for the ignition pulse (LT side of coil, EDIS module etc) - and this shouldn't need adjusting. The adjuster wotsit is for if you are driving it from the W terminal on an alternator (eg. on a diesel where there's no coil) - as the pulley sizes for different cars vary, the alternator spins at a different speed, so you have to calibrate the alternator pulse to get the rev counter to read reasonably accurately.. Quote Link to comment Share on other sites More sharing options...
need4speed Posted June 28, 2015 Author Share Posted June 28, 2015 Yeah I'm driving it from the "W" on my alt.. Quote Link to comment Share on other sites More sharing options...
=jon= Posted June 28, 2015 Share Posted June 28, 2015 Ahh, OK. I'm about to fit one to my v8, I was going to try and run it off the megasquirt or the EDIS pulse... Quote Link to comment Share on other sites More sharing options...
Jocklandjohn Posted July 1, 2015 Share Posted July 1, 2015 A laser tach is the easiest way to get it adjusted correctly. Cheap and good to have for the future. http://www.ebay.co.uk/itm/like/201276438867?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=108&chn=ps&device=c&rlsatarget=&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0-L&ff12=67&ff13=80&ff14=108 Instructions: http://static.summitracing.com/global/images/instructions/vdo-333158.pdf I just bought one of these, it arrived in a few days. Fitted a tacho today, stuck the reflective tape (x 2) on the crank pulley and fired the laser - ping - instant reading which, when divided by 2, gave me the correct rpm to set the tacho to. (EDIT: Well I assume its the correct rpm!) Thoroughly recommend it. Quote Link to comment Share on other sites More sharing options...
western Posted July 1, 2015 Share Posted July 1, 2015 idle between 750 to 850rpm, max revs [no load/not moving] 3850rpm. Quote Link to comment Share on other sites More sharing options...
Jocklandjohn Posted July 2, 2015 Share Posted July 2, 2015 idle between 750 to 850rpm, max revs [no load/not moving] 3850rpm. Cheers Ralph - it was 760 RPM and a slight increase when warmed up. Useful tool for £10 and will give my 7 year old a heap of fun figuring out rpm's on various things from his bike wheels to the blades of his RC helicopter! 2 Quote Link to comment Share on other sites More sharing options...
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