Speedometer Poll

I might have a spare airguide speedo (used)that I would sell cheap. SKIDIM still sells compatible pick-up pitots. I believe the speedo needs a 4" hole (might be 3.5", can't remember right now). I do not think anyone makes a speedo for a 2" hole. Otherwise, your more common choices are Faria and Teleflex.

Now tell me how a speedo will help with engine timing? FWIW, I use my tach to gauge and control speed more than my speedo on the '77.

Jim, My boat had a 65mph teleflex spedo originally. It reads like a log scale (low speed graduations close together, high speed graduations far apart). I hated it because I spend most of my time pulling at the lower speeds and it was hard to read. I replaced it with an Airguide, which is contralog (the opposite of log) and I love it! There are also electronic spedos available. They have a scale with even graduations all the way up and they run off of a paddle-wheel.

Jim,
    This may sound crazy but if you are only wanting to tune your boat and check your prop you may consider a hand held GPS monitor(one that displays speed). This will give you an accurate reading and you can use it from one boat to another to calibrate with. I have a Garmin E-Trex and it was $100.00 and it gives you the speed and mine is accurate to my truck's speedometer.
    Now if you are wanting to install a speedometer in your boat for everyday use and not just for the tuning, then my GPS idea might not be feasible. Although,I clip mine in between the two airguides when i'm in my boat, I think it is more accurate than the boat and it never needs adjusting.

Just an idea