mikewest Posted March 1, 2020 Share Posted March 1, 2020 I have a teens Corbin Brown tachometer I have connected to my engine off the end of the camshaft. I know the camshaft runs at 50% of crankshaft speed. Has anyone reading this had any experience changing the gearing in the camshaft or know of someone that can? Thank you Mike Link to comment Share on other sites More sharing options...
Str8-8-Dave Posted March 1, 2020 Share Posted March 1, 2020 Not sure you would change the camshaft gearing, it would never stay in time with the crank. Yes it absolutely runs 1/2 crank speed. Assuming your tachometer was designed to measure crank speed revs you could just double the tach reading. If that doesn't work for you and you have a convenient way to connect the end of the cam to a cable or input shaft of a small gear box you could try to find or make a 1 to 2 ratio up-drive to go between the tach and the cam. To get some expert advice and maybe an up drive or conversion of your tach you could try Bob's Speedometer https://www.bobsspeedometer.com/1/120/index.asp Link to comment Share on other sites More sharing options...
mikewest Posted March 2, 2020 Author Share Posted March 2, 2020 Dave, You are correct. My tachometer came off a period starter /generator test bench and it is 1 to 1 gearing. Im not going to monkey with the gearing on the motor. I think the 2-1 gearbox will be the easy fix. Ill check with Bobs. Thanks Mike Link to comment Share on other sites More sharing options...
JV Puleo Posted March 10, 2020 Share Posted March 10, 2020 Mike... I looked into fitting a tach to my Mitchell and found that they actually aren't geared to the shaft. They use something akin to an old engine governor...spinning weights pressing against a spring. The reading on the dial is determined by the strength of the spring. I've never taken one apart to look inside because I eventually decided not to do it but I still have the tach...it's yours if you can use it. j Link to comment Share on other sites More sharing options...
mikewest Posted March 12, 2020 Author Share Posted March 12, 2020 Joe , I have several tachs and have the one I want to use. I wonder if they could be adjusted to read more correct. I haven't found much info on them. The so called expert I called said get some stickers and change the numbers to half of what the say.... OK I can do that without a sticker. Link to comment Share on other sites More sharing options...
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