ENGINE BUILDERS REJOICE! DIAMOND PISTON’S NEW COMBUSTION CHAMBER MOLD KIT—if you alter the combustion chamber, altering the piston dome to suit is simple

Written by Moore Good Ink

Clinton Township, MI: Diamond Pistons has introduced its combustion chamber mold kit, the first such complete checking device to ever appear in the automotive aftermarket. While making an impression of the cylinder head combustion chamber is well-known, Diamond provides a break-through by including all the materials needed in a single package.


 When cylinder head combustion chambers are modified and dome pistons are required, an accurate mold reflecting the inverse image of the combustion chamber is necessary. By pouring an epoxy mold, all the necessary data the piston maker requires will be captured, except the depth of the valve pockets. The data includes valve center lines, the valve positioning in relationship to the cylinder, the angle of the valves, and an accurate chamber footprint from which the dome can be formed.


Thickness of the head gasket is another critical consideration. The thicker the gasket, the greater the volume in the combustion chamber will be. From the mold shape, a piston can be designed with the perfect crown profile. Also, the mold kit can be used to calculate the compression ratio as well as cubic centimeter (cc) capacity of the combustion chamber. With regard to valve pocket depth, if the engine builder is unsure as to how far the valves will travel toward the piston, Diamond will provide them a sample piston with estimated valve pockets incorporated. They in turn can fit the sample piston to the engine and advise Diamond of any adjustments necessary.


A mold is produced by fixing a fully assembled cylinder head (with a substitute spark plug in place) on an empty block (without head gasket), turning it upside-down, and applying WD-40, a light coat of oil, or silicone spray to the cylinder bore. Mix the two epoxy mediums in a 1:1 ratio for 2-3 minutes, pour the mixture in from the bottom of the bore in an amount at least 0.150-inches up the cylinder wall, and let cure for 30 minutes. If the heads are canted valve type, before removing the chamber mold from the head, install the dowel pins, set a straight edge against them, and scribe a parallel line on the back side of the mold, as shown in the instructions supplied. Ship the mold to Diamond in the container provided with the kit.                    


Diamond scrutinizes the customer’s mold with a 3D laser scanner to determine the dimensions needed to develop the most advantageous dome configuration.  In some cases, engine builders require the piston dome to fill as much of the combustion chamber as possible while others only want to fill as much of the chamber as needed to achieve a pre-determined static compression ratio. This new Diamond chamber mold kit, which costs $42, achieves it all.



For more information contact:

Diamond Pistons

23003 Diamond Drive, Clinton Township, MI 48035

Telephone (877) 552-2112 or visit www.DiamondRacing.net


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