1420 engine speed verification?

[Dave from MN]

OK, as shared earlier this fall, my 1420 I purchased only shows 2300-2350 rpm"s at full throttle. It did a great job, but a little lacking in power in real heavy, corn and stalks. It is supposed to be at 2900 rpm"s under no load. Does any one have any advice on how I can check if it is actually running that slow, or if the tach could be out of calibraion.? I am assuming it IS that the engine is not running that fast, but how can I measure it?
 

[JMS/.MN]

There are mechanical tachs that you hold against the end of the turning shaft to measure speed. I have my Dad"s that he bought in 1948, along with the AC combine. Also an identical one from an auction box.....maybe Lufkin brand?
 

[sdc eastern ia]

Stewart Warner makes a good hand held tach. Check on flea bay I've seen them there.
 

[Mike Aylward]

In addition to what the others said you can buy a laser tach that uses magnetic strips attached to a pulley or shaft that work very well. I've seen them several places for less than $100. Mike