Wiring up Tacho with BJ40
- Thread starter RyRy
- Start date
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I don't think there is a stock sensor for a tach on the B-engine.
Easiest way is to derive a tach-signal from the alternator. You'll need an adjustable tachometer though (VDO makes them), because alternator rpm's differ from engine rpm's. After installing you will have to adjust the tach with a reference. A good equipped repair shop has a tach that derives the rpm's by a vibration detector; that will work as a reference.
There are other, but more difficult, ways like a pressure sensor on one of the fuel lines. Or a magnetic or light sensor at the engine pulley. But those methods require additional electronic devices.
Ton
Easiest way is to derive a tach-signal from the alternator. You'll need an adjustable tachometer though (VDO makes them), because alternator rpm's differ from engine rpm's. After installing you will have to adjust the tach with a reference. A good equipped repair shop has a tach that derives the rpm's by a vibration detector; that will work as a reference.
There are other, but more difficult, ways like a pressure sensor on one of the fuel lines. Or a magnetic or light sensor at the engine pulley. But those methods require additional electronic devices.
Ton
[quote author=RyRy link=board=21;threadid=16833;start=msg162329#msg162329 date=1085328860]
Hi,
Is it possible to wire up a tacho with a 1978 BJ40 ? Where would i get the signal from? I know with petrol engines its usually from the coil, but i have no idea with this car. Thanks
Ryan
[/quote]
Later model BJ4# came with tachs. So it is possible. In fact if you look long enough I am sure you can find a used tach and the wirring.
Hi,
Is it possible to wire up a tacho with a 1978 BJ40 ? Where would i get the signal from? I know with petrol engines its usually from the coil, but i have no idea with this car. Thanks
Ryan
[/quote]
Later model BJ4# came with tachs. So it is possible. In fact if you look long enough I am sure you can find a used tach and the wirring.
i dont think the early ones came with a place to mount the tach sensor though. You might also be mathematically skilled enough to work out the reference by the number of rpm printed on the bottom of the odometer. it says something like 632rpm / 60km/h which if you can find out the ratio of the odo drive gear to the output drive on the t-case would give you close rpm.
sam
sam
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Ahh its a B motor, rev it till the power drops and thats usually way before it hits redline..............
I bought an alternator driven tachometer for my diesel. This is the one but I've seen similar units for at little as $10 complete on ebay...
http://store.summitracing.com/partdetail.asp?part=ATM-2888
Only thing is you have to calibrate it, I did it by finding where my torque curve (1800 rpms) drops off and adjusting it to that. Way easy though and awesome addition! I don't have an operational speedo yet so I let the tach tell me how fact I am going for now
http://store.summitracing.com/partdetail.asp?part=ATM-2888
Only thing is you have to calibrate it, I did it by finding where my torque curve (1800 rpms) drops off and adjusting it to that. Way easy though and awesome addition! I don't have an operational speedo yet so I let the tach tell me how fact I am going for now
