[V8Vairs] Tach

[paulsiano@aol.com]

I will check the tach closely and get back to you.  I forwarded your email to Don.
 
Given the time of day, neither of us go a great night's sleep, eh?
 
Paul

--- On Mon, 9/27/10, Frank Parker <fparker at umich.edu> wrote:


From: Frank Parker <fparker at umich.edu>
Subject: [V8Vairs] Tach
To: "discussion of non-stock engines in Corvairs" <v8vairs at corvair.org>
Date: Monday, September 27, 2010, 5:03 AM


I have ffigured out rpm problem. Tachs are calibrated for6 cyl
Take the 5880 rpm I guessed from tire circum and don,s upposed
7500 rpm run, use 5880 rpm & tire dia, get roolouut in ft for every wheel rev by div by 3,55 diff, getwheel ft rolled in hr, div 5280yields mph for5880…& u get 120 mph but at 5880 rpm not
7500. When u adj the stock tach, u turned the wrong pot. Best if
Done with a cap. Second tach was on 6 cyl too
Proof; take the actual tire dia and ratios and pure math and I get
Correct 120 top speed,/ div 5880/7500 &*u get 3/4 or 6/8 cyl
Thus the tach is off by exact ratio of tach being set to 6 cyl but
Getting 8 cyl pulses; both tachs wrong. Stock tach needs a capacitor to be correct. New one needs a wire loop out back side
Of tach cut

Frank
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