The cylinder honing process assures precision sizing plus exact Ra finish in every cylinder in any type block. Promar finds that the automatic Sunnen CV-616 Cylinder Hone ensures better than original factory accuracy and corrects taper and out-of-round. Another benefit is that it produces surface finish, size, roundness and straightness tolerances equal to or better than original manufacturer's specs. The CV-616 produces consistent precision surface finish with uniform crosshatch pattern in each cylinder.
CV-616 provides base metal finish, free from fractured metal for immediate ring seating and positive oil control. It works for passenger cars, high performance engines, trucks, diesel and industrial blocks. This precision machinery hones any material including aluminum, cast iron and any alloy.

Promar insures proper measurement of Ra by utilizing the Mitutoyo SJ-301 surface tester.

Milling machines that are used by Promar are set up specifically 1 for blocks and 1 for heads. The Winona Van Norman M3000 machines are used for their variable feed rate, which is essential to acquire proper Ra finish for each block. Ra finish determination is based on the type of block, be it aluminum or cast iron, and by the type of gasket used for each specific application. These machines utilize CBN (cubic boron nitride) cutters, which are second in hardness only to a diamond. During the cutting process heat from friction is absorbed and carried off by the discarded metal chips thus resulting in improved accuracy and excellent surface finish. The surface finish is then checked by using the Mitutoyo SJ-301. The Mitutoyo SJ-301 is utilized twice, once after resurfacing and again before final assembly Promar insures proper measurement of Ra by using the SJ-301. The next process is rod reconditioning.

Continuing our efforts to produce the best and most reliable product in the industry, we utilize the Berco RTM 225A precision crankshaft grinder. Coupled with our expert craftsmen, this state-of-the-art unit incorporates rigid construction and precise controls; affording Promar customers the most accurately ground crankshafts possible. Precise controls afford precision grinding, which is followed up by brush cleaning and chamfering of all oil passages.

Promar uses a crankshaft micro-polisher with a rigid polishing system. The QPAC Q190-38-3 has a solid abrasive tape that wraps around the journal and is backed up with a shoe. This shoe applies equal pressure all the way around the journal while it is being polished.

Traditional polishing techniques use a manually operated belt sander that can alter the geometry of the journal, slightly creating some taper or out-of-roundness. If the surface finish on the crankshaft journal is not right or the geometry is slightly off, the bearings will suffer the consequences when the crankshaft is put into service. While polishing in one direction and then automatically polishing in the opposite direction, the QPAC system leaves a better finish and eliminates microscopic peaks that can cause premature bearing failure. The finishing process always ends in the same direction as the engine rotation.

For thrust surfaces, a separate polishing arm is used. Polishing the thrust surface on the crank is important to minimize the risk of thrust failure on vehicles that have electronic torque converters.

With many of today's engines requiring extremely smooth journal finishes (as low as 6 Ra or less) because of tighter bearing clearances and the use of thinner viscosity 5W-30 motor oils, there is little margin for error. In one pass the QPAC takes the finish down to 6 Ra or less and provides a superior finish to any polishing systems out there today.

Magnetic particle inspection is the most definitive methods of detecting cracks and imperfections in any ferrous engine parts. This procedure assures the highest quality crankshaft cores for remanufacturing.