Larry

The engine plus a second for spares only cost 60UKP.
I experimented at the weekend, and have solved my problem.
1. Built a circuit that uses an optical sensor
2. Removed the circuit board from inside the tacho, so it's just a moving
coil meter.
3. Put 2 white blobs on the flywheel.
4. Calibrated the circuit.
Works wonderful.

Regards,
Brian
http://homepage.ntlworld.com/brunyard


"Larry W4CSC" wrote in message
...
On Fri, 14 Nov 2003 19:29:08 -0000, "Brian Runyard"
wrote:

Larry

I don't have the Perkins tach, so before parting with hard earned cash I
wondered if I could modify what I've got.
The engine is a Perkins Prima 78hp Turbo, out of a car so I've got to
spend
about £700 for the marinising kit.
Regards,
Brian

Ah, sorry. I got a clearer picture of your problem, now. We just
paid $US1200 for a 4-108 with 700 hours on it from a guy who went
Yanmar right from this newsgroup. The engine has been delved into and
is in fine condition, especially for $US1200! It will soon replace
the 4-108 in Lionheart which has about 7000 hours on it. The new
engine has a nicer panel than the old one, so it will all be replaced,
too, getting rid of the car oil guage, etc., for the Perkins that
matches.

I don't see where you'd get the pulses from a diesel the old ignition
system gave you for that tach. If the old engine were a 4-stroke,
4-cylinder, you got 2 pulses per revolution. An alternator is very
high frequency in comparison so I don't think that will work. There
might be a way to get a magnetic pickup to pulse the tach from a
couple of magnets on the flywheel, but I'm not sure how I'd trust a
jury rig on something as important as the main engine, even on a
sailboat.



Larry W4CSC

"Very funny, Scotty! Now, BEAM ME MY CLOTHES! KIRK OUT!"