Re: Ign timing; advance vs retard

["Graydon D. Stuckey" <graydon@apollo.gmi.edu>]

On Thu, 15 Aug 1996, Robert Houk - SMCC Bos Desktop Hardware wrote:

> I wanna make sure I've got this right. Without delving into the myriads
> of reasons why (relative angle of crank/con rods; varying values of com-
> bustion burn rate depending on instantaneous cylinder pressure; etc, and
> so forth) the ignition timing is a variable, one "advances" the timing
> by causing it to fire earlier in time, or at a "larger" BTDC value, cor-
> rect? I.e., 10 deg BTDC is 'advanced' timing relative to 5 deg BTDC?
RDH,

	Yes, you have it correct.  Another way of looking at it, is to 
graph piston position with respect to time.  It will look roughly 
(exactly?) like a sine wave, with the very top being TDC.  Anything that 
happens before that top is called before top dead center, or BTDC, so an 
event that happens at a greater number BTDC is more advanced.

Later, ---------------------------------------------------------- 
Graydon D. Stuckey 	'85 Mazda RX7 GS, no toys 
graydon@apollo.gmi.edu 	'86 Audi 5000 CS Turbo Quattro, has toys
Flint, Michigan USA	'89 Thunderbird SC, lotsa toys