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".
Flexible Honing for Engine Cylinders
Although datzenmike recommended renting a "bottle
brush style hone", MicroMachinery bought an 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 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. Flexible honing 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.
Author's Note: This CR4 blog entry appeared originally on BRM's Flex-Hone Blog.
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