[Land-speed] Torque Drop>From>JG Magoo

[John Burk]

Top fuel spark lead varies with the shape of the combustion chamber . Blown 
fuel 392 hemis ran best with 19 to 28 deg with extreme of 32 deg . It took 
several years for the Ramchargers , Keith Black and Garlits to realize that 
426 hemis needed way more . In '66 or early '67 Black tried 40 deg which 
wasn't enough and he quickly pulled it back for fear it was way too much . 
Spark advance is not linear . When the piston is half way up the fuel burns 
relatively slowly . A fellow I know got the mag a tooth off on his top 
fueler which was about 140 deg and it ran about the same .



> Top Fuel engines need that much timing advance because of the fuel, not 
> the
> rpm.  Nitromethane burns much slower than gasoline, so the timing needs to 
> be
> advanced more to maximize power.