Here are the ‘very summarized’ results of how sixteen different pairs of heads recently performed on the 312 dyno mule.  A pair of the ECZ-C’s and C1TE-D’s was a before and after milling comparison which  jumps the number of published tests to eighteen.  The same carburetor, intake, headers, timing, and valve lash was used in all these tests.  The camshaft is a Crower Monarch with 0.450” lift, 238°@0.050”, ground on 110° lobe centers, and installed 2° advanced or 108° intake lobe centerline.    The intake manifold is an unported Mummert dual plane paired up with a 750cfm vacuum secondary Holley sitting atop a 2” oval opening carb spacer.  1.6:1 roller rockers are being used for all tests.  Total ignition timing is 38° BTDC.  For these particular test results, the headers are used with mufflers which helps to keep this particular information set comparable.  The degree or amount of porting when performed on the heads is not listed on this particular chart.

A special thanks goes out to those of you that donated heads, shipping, and/or funds to make all this happen.  For those of you that sent funds without any name(s) on the envelopes, an extra thanks also.  This testing has generated a plethora of information which is being put together for a series of articles for the Y-Block Magazine.

Lorena, Texas (South of Waco)