| Author |
Message |
Chuck MC8 (67.33.171.207)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, July 08, 2003 - 2:14 pm: | |
I want to put in an electric tachometer in my MC8 with 8V71. What signals/triggers it on the engine? |
Earl-8-Ky (207.162.163.19)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, July 08, 2003 - 8:52 pm: | |
Chuck I think you will find the best place to hook a tachometer to is the Generator |
JimStacy (12.87.110.70)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, July 08, 2003 - 10:28 pm: | |
The "R" terminal on the alternator is the usual pickup spot. Most tachs have a dip switch for calibration with a recommended setting for the "R" terminal output.
Jim Stacy |
Chuck MC8 (68.158.69.53)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 09, 2003 - 6:23 am: | |
Does it have to be a 24V Tachometer? |
Gary Stadler (Boogiethecat) (68.7.217.217)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 09, 2003 - 9:08 am: | |
Chuck,
If you have a 12 volt tachometer and have the means to feed it 12 volts, it probably doesn't matter if you hook the pulse input wire to a 24 volt alternator, because that wire is fairly well protected (inside the tach) against all sorts of nasty electrical spikes, etc. and 24 volts on the pulse input wouldn't hurt it
For me, I found it a lot easier to get a tach that works with an inductive pickup, then I simply drilled a 3/4" hole in my bellhousing and bolted the pickup in so it sits almost touching the starter ring gear teeth. Works perfectly, and it's a complete system with no surprises.
If you don't have 12 volts availiable to power the tacho itself, you can use a simple 3-wire regulator chip from Digikey (www.digikey.com) to create enough 12 volts out of 24 to run the tach. If you need this, use part #296-11111-5-ND (TI part number UA7812CKC) It's a transistor- looking thing that will take up to 35 volts and create 12 volts at up to 1.5 amps if you heatsink it. It's three terminals are: Input-Ground-Output.
For a tach it probably can just be wired in and insulated with tape. If you need further detail, write me...
Cheers
Gary |
Geoff (Geoff) (66.238.122.223)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 09, 2003 - 7:28 pm: | |
I have an Isspro catalog and there is a couple of items that might be useful-- one is a 24v-12v voltage reducer for running 12v gauges in a 24 volt system, the other is an alternator tach that is either 12v or 24 volt. On my RTS I used a programable tach with a magnetic pickup on the front crankshaft using two magnets 180 degrees apart and set the dipswitch for a 2 to 1 ratio. Needless to say it is very accurate-- something you don't always find in alternator tachometers. |
degojo (205.188.208.39)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 09, 2003 - 10:07 pm: | |
a gear driven alternator provides a reliable input for a tach |
Geoff (Geoff) (66.238.122.223)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 09, 2003 - 10:24 pm: | |
A gear driven alternator only provides correct reading IF the tachometer recognizes the ratio-- that is why I went with the mag sensor-- Isspro tachs don't have the ratio available for the gear driven alternator. You have to check each manufacturer's specs to see if it will work for you. |
degojo (152.163.252.163)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 10, 2003 - 1:18 pm: | |
The output of an alternator is directly proportional to its rpm. a gear driven alternator does not have the slipping problems associated with belt drive. An accurate inexpensive tach can be made guaging the alternator output and modifying the guage to read RPM |