Marine Tach for Pump

[Freakwater]

The sled I bought has a tach that's wack. The motor is a four cyl. merc 115. The guy I bought it from put an automotive tach on it. I need to replace it and I'm pretty clueless. Dood said just to make sure it's a 4 cyl. tach. Should I get a marine tach vs. an automotive one? I assume an automotive one is cheaper, and maybe why the last one did not last. Saw one at West Marine and it was crazy expensive.

I guess the question to ask first is how important is a tach for a jet?


Thanks

[ 11-19-2003, 08:20 PM: Message edited by: Freakwater ]

[1pump]

Some tachs are adjustable for number of cylinders, but the main thing is that you'll need a 2-stroke tach. Otherwise the tach will think the engine is running twice as fast as it really is.
Teleflex is a popular brand. I'd get a marine tach due to exposure to moisture and whatnot.
You might check the websites of Stewart Warner, Autometer, VDO etc and see if they have any marine types.

[ISeeFish]

Here's a link tach

[Freakwater]

Thanks for the help.

1pump...those are some cool sites.

IseeFish....that looks like what I'm looking for.....I think?

I think I'm more confused though. Better now than after I buy a tach.
What's up with senders?
How do I know if the sender is busted rather than the tach?
Are there different type of senders? Gas?
1pump...I see nothing about 4 stroke vs. 2 stroke.

Appreciate any help...
Thanks,
Freak

[1pump]

Here's a link to a Teleflex tach setting chart.


Tach setting

I need to clarify what I said earlier about 2-strokes.
If the tach runs off of alternator pulses, then 2 or 4 stroke doesn't matter. Alternators don't care what's driving them.
If the tach runs off of the coils or ignition then there's a big difference, 'cuz 2-strokes fire on every revolution rather than every other rev.
The Teleflex tachs use dipswitches to set the tach for the motor it's used on.
I just looked at S-W's site and saw that they have a marine line of gauges that has a choice of several colors. Heaven forbid that your tach clashes with your carpeting or your Gore-Tex jacket. You'd get laughed right out of a hogline. :blush: :shocked:

Most tachs don't use senders unless it's for a mag or "Hall Effect" type. My Merc doesn't have a tach, so I never had to screw with one.
As far as a tach being necessary, this is my .02:
If there was a tach there in the first place, I'd keep it. I hate staring at big holes in an instrument panel or at gauges that don't work. If it didn't have one, no biggie. 2-strokes are designed to be run full-out anyway, and if you're running a jet in shallow water, you're going to be listening to the motor and watching the river, not looking at a tach, especially if it's mounted out of your line of sight.
Just my take; I'm sure others would feel differently.

[ 11-20-2003, 01:20 AM: Message edited by: 1pump ]