I got a Motorola 7SP2025 tach but no sensor. Can anyone tell me if there is a sensor(sender) I can use with my 12 valve. I use it in an older RV and want to check the RPM to change the rear end ratios. It does not have to work forever.

 

Need a little more info on the engine style might help. I had a motorola tach on my 89 CTD and it ran off of one of the alternator fields, had to fine tune to make it accurate.

 

I took the engine and auto trans out of a 93 Pickup.
I need RPM to change out the ring and pinion.
It is screaming at 55 mph with a 4.54:1 ratio in a 24' Commander.
I wired it to the CPS but got a 1/6th reading.
Can you advise how to hook to alternator?
Thanks

 

I took the engine and auto trans out of a 93 Pickup.
I need RPM to change out the ring and pinion.
It is screaming at 55 mph with a 4.54:1 ratio in a 24' Commander.
I wired it to the CPS but got a 1/6th reading.
Can you advise how to hook to alternator?
Thanks

 

Sorry, unable to PM Li'l Dog
Everything is out of a 93 Dodge 3/4 ton.
The RV cost $2 but the engine etc cost $3500.
I replaced the injector pump and starter.
I also installed a redundant Voltage regulator on an 'either or toggle'.
The PCM is slowly coming alive so the O.D. & TC lock-up work now.
I still I have lots of electrical gremlins but will likely keep the rig forever.

 

Getting 1/6 the reading is odd. The CPS runs on a notch in the balancer so there is a once per turn pulse.

On the back of the alternator under the cover, there are connectors nut/washer that go to each of the 4(I think) fields of the alternator. I would have to have the alternator in front of me to be sure as if its not the OEM, I would be sorta lost. Alternators aren't that advanced, but anyway I don't know if the frequency of the pulses would work for the tach you have.. Hmm.

 

I did a quick search and found this... http://news.prestolite.com/node/3555

Looks like it should work with the alternator and then have a pot to adjust the RPM output..