TOPIC: Airguide Tach Testing

Subject: 1973 Johnson 115 V4 - Airguide Seaspeed Tach

Okay y'all, the digital test tach test is finally completed. I ended up having to paint the flywheel flat black so it would pick up the reflective strip in the direct sunlight, and installed a fresh set of batteries, but the results are now in:

At 2000 on the tach, the digital reads 1255
At 3000 on the tach, the digital reads 1813
At 4000 on the tach, the digital reads 2297

Since I was running it on the ear muffs, I didn't go any higher than that. That last reading may not be entirely accurate as the RPM's were climbing and I hurried to finish and idle down, then shut down.
Remember this ???
Think I need a new tach !!!

wow....do you think speedos could be off that percentage.

Wonder if that tach is set for a four stroke by mistake- tach is reading about two times actual. Does it have a settings switch on back?

Ron wrote:

wow....do you think speedos could be off that percentage.

I'm told the Airguide speedo's are more accurate than their tachs. I don't know, don't have GPS. Been looking for a good deal on a used unit, the new ones are out of my price range right now. Maybe Santa will bring me one for Christmas!? Joe Poole has a nice new speedo I'd like to get that would match my new tach, I'm saving up for that now.

Kerry wrote:

Wonder if that tach is set for a four stroke by mistake- tach is reading about two times actual. Does it have a settings switch on back?

It had "settings" on the back, and was set for reading the alternator pulses as it should have been. It was just a bad unit I think. I have since replaced the tach, you can see it on this thread from where I was doing some prop testing last weekend:http://www.fiberglassics.com/glassic-forums/the-70-s-disco-fiber/1973-glastron-v178-starflite-project/page-2#10135