gauges help

[Andy in NY]

motor is a 1974 evinrude 50 hp outboard.

i was given a gauge cluster from a mercruser sterndrive setup and would like to see if i can make any if the gauges work with my motor? the 3 in question would be volt meter, which i would assume would work with anything...

the second is a temp gauge. i know my evinrude has an overheat alarm, can i use the existing temp sensor and hook it to the gauge or will i need a new temp sensor?

third is the tach. can a tach frrom a 4 stroke 4 cyl work with a 2 stroke 2cyl?

 

[Andy in NY]

Re: gauges help

anyone?

 

[flargin]

Re: gauges help

Temp gauge, you will need a new sending unit. The overheat is a switch, when the temp gets too hot, it turns on the light. A temp gauge uses different resistance at different temperatures. I don't know if it would work, but I doubt they would use different ranges -- but someone else may know.

Volt meter - yes.

Tach - unlikely

 

[Silvertip]

Re: gauges help

The only gauge that will work without exception is the voltmeter. Whether or not the temp gauge does you any good depends on what the scale reads. I/O engines run hotter than outboards so if you have a 120 - 240 gauge, the needle will hardly move off the low end of the scale on your outboard. NO - the temp sender on your outboard is a switch - it is either open or closed. You need a 33-240 ohm temp sender available from any number of sources including right here on iBoats. As for the tach, this is another IF. Automotive engines (as in I/Os) have an ignition system that produces pulses based on the number of cylinders and those pulses are generated at a rate that is 1/2 crankshaft speed since this is a four stroke motor. Outboard tachs are driven by a pulses from the stator and are therefore NOT number of cylinder related. While it is true that you could pick off the primary side of one of the coils on the outboard to provide a cylinder based signal but it would generate a pulse once every rev. The next issue is whether or not the electronics in the tach can recognize that "foreign" pulse. The last issue is you would then need to determine if the tach has a cylinder selector switch. You need to do the math to find the setting that works for your engine. If you are getting the impression that you should have bought Outboard gauges, you would be correct.

 

[Andy in NY]

Re: gauges help

The only gauge that will work without exception is the voltmeter. Whether or not the temp gauge does you any good depends on what the scale reads. I/O engines run hotter than outboards so if you have a 120 - 240 gauge, the needle will hardly move off the low end of the scale on your outboard. NO - the temp sender on your outboard is a switch - it is either open or closed. You need a 33-240 ohm temp sender available from any number of sources including right here on iBoats. As for the tach, this is another IF. Automotive engines (as in I/Os) have an ignition system that produces pulses based on the number of cylinders and those pulses are generated at a rate that is 1/2 crankshaft speed since this is a four stroke motor. Outboard tachs are driven by a pulses from the stator and are therefore NOT number of cylinder related. While it is true that you could pick off the primary side of one of the coils on the outboard to provide a cylinder based signal but it would generate a pulse once every rev. The next issue is whether or not the electronics in the tach can recognize that "foreign" pulse. The last issue is you would then need to determine if the tach has a cylinder selector switch. You need to do the math to find the setting that works for your engine. If you are getting the impression that you should have bought Outboard gauges, you would be correct.

thanks, thats what i thought. they were given to me so its no biggie.