Thread: Question about formula 4 dynamic comp.

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The KB calculator says to add 15 degrees to the 0.050" tappet lift to get you close to the actual 0.006" tappet lift point. They're figuring that there is about 30 degrees of cam rotation between the 0.006" tappet lift figure and the 0.050" tappet lift figure, 15 degrees on the opening ramp and 15 degrees on the closing ramp. To use it with a 0.006" tappet lift figure, simply use the 0.006" figure you have and do not add 15 degrees. In researching this point of engine building, most posters on other sites agree that the KB site is conservative, so that instead of using the ideal 8.00 to 1 that other calculators produce, use results that equal 8.25 to 8.50 with the KB calculator.
http://kb-silvolite.com/calc.php?action=comp2

Of course, when optimizing the DCR on a motor, you have to be certain that other areas of the build are in synch. Squish optimized at 0.035" to 0.040", chambers polished and sharp edges chamfered to eliminate hot spots, spark plug electrodes de-burred with a fine wet/dry paper, no gasket overhang into the cylinder (try to match the gasket to the widest point of the cylinder at the top of the bore where the bore is chamfered to assist getting the rings into the bore on assembly so that you have neither gasket overhang or a crevice where mixture can hide and be left unburned) and perhaps routing the PCV into the headers instead of polluting the fresh intake charge.