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Using Phototach on Crusader 270s

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Dan Eagle

New member
Thanks in advance for anyone responding to my very basic question regarding use of a phototach on my crusader 270s which I am doing to better calibrate my tach gauges. I need to attach the reflective sqaure to one of the front center pulleys - i think the top center pulley runs the FWC pump and the bottom is the "crank"? Is that right and does it matter which I use to get the reading? Thanks
 
If they are the same size (diameter) it won't matter...if you haven't measured them, use the crank directly. You can also use the flywheel, accessible thru the bell housing cover, for the reflector.
 
I'd use either the crankshaft pulley, or as Mark said, the flywheel.


Don't give yourself any margin for error regarding pulley diameter or pulley belt groove width.
Either could throw things off, in that it doesn't take much X's your testing @ 1k, 2k, or 3k rpm to cause an error in accuracy.

Shoot for perfection in hopes for adequate. :)


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The harmonic balancer may be a good spot for the tape. Give it a good cleaning before sticking it on.
 
Dan, I missed my oportunity to edit my previous post, but wanted to add something to this.

You're adjusting or recalibrating your tachometers, correct?
You very likely won't acheive an accurate reading at all RPM ranges. Meaning that while you calibrate them accurately @ 1k rpm, they may not be correct @ 3k rpm.
If your cruising RPM is more important to you, then you'll want to calibrate them at/near 3k or 3.5k rpm.
But you probaly know this.

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