Engine Rebuild: The Flex-Hone® and the Datsun LZ22

Ratsun Rules is an on-line automotive forum where Datsun mechanics ask questions and get answers about engine rebuilds and car repairs. Although Nissan Motors retired the Datsun mark over 25 years ago, engine tuners still exchange advice about Datsun parts, equipment, and tooling. While rebuilding an LZ22 engine, a user named MicroMachinery explained that “ball hones are the cat’s meow” for honing engine cylinders. Flex-Hone® fans have given our honing tools some colorful nicknames over the years, but “cat’s meow” seems fitting since flexible honing keeps your engine purring.

Engine Rebuilds and Cylinder Walls

When MicroMachinery first tore-down his LZ22, the engine mechanic asked Ratsun Rules if a rebuild was really necessary. “The cylinder walls have hardly a ridge, if any”, MicroMachinery explained. The previous owner was a master of engine maintenance – even if the block did have 200,000 miles. That’s when another Ratsun user, datzenmike, warned that “once a piston is out, the rings have lost their original placement”. So unless the engine cylinders are worn over their stock limit, a good mechanic needs to hone the walls and install a new set of piston rings for “compression and power”.

The Flex-Hone® for Engine Cylinders
Although datzenmike recommended just renting a “bottle brush style hone”, MicroMachinery ended up buying the engine honing tool that’s truly “the cat’s meow”.  Built with a stiff metal stem, flexible nylon strands, and abrasive globules that come in a selection of grits and abrasive types, the Flex-Hone® from Brush Research Manufacturing (BRM) is easy-to-use and mounts in a handheld electric drill. As the picture that accompanies this blog entry shows, the difference between a honed cylinder (left) and an un-honed cylinder (right) is striking.

Piston Rings and Engine Performance

When new piston rings are installed, the walls of engine cylinders must be given the right “scratch pattern” to promote proper seating and optimum lubrication. By using the Flex-Hone®, mechanics and machinists can remove the peaks produced by prior honing operations to create a flat, smooth cross-hatch surface for a plateau finish. The Flex-Hone® tool from BRM is also ideal for deglazing, the process of removing the polished surface or glaze from the walls of engine cylinders.

 Metallurgical Microstructures and Expert Advice

Although some surface improvements (such as the ones in this blog entry’s picture) are visible to the naked eye, BRM’s A Study of Cylinder-Wall Micro-Structure harnesses the power of scanning electron microscopy (SEM) to compare the results of cylinder honing with rigid hones vs. the Flex-Hone® tool. Just as Datsun lovers visit Ratsun Rules for expert advice about their vehicles, we hope you’ll visit the Technical Books section of the BRM website for helpful information about flexible honing.