Shop Friday

Gravity is silent. The stately tick-tock of the pendulum clock is the
only sound in the shop, the lathes and mills lurking beneath their
shrouds as I try to reason with Mr. Ohaus. Unlike the clock, which is
made of wood, Mr. Ohaus is a man of metal but both are powered by
gravity. A spate of rain sweeps over us, loud on the metal roof out
behind the shop and for a moment I hope it will somehow change Mr.
Ohaus' mind but he is stubbornly insistent: the connecting rod weighs
605.9 grams.

Deep sigh.

I take the rod out back where the narrow belt of the polishing sander
whisks away another film of metal, first on one side, then the other.
Then follows a careful cleaning and back to the scale: 605.7, less a
tad. I repeat the ritual as more rain blows in, a regular shower this
time. I give the belt-sander two-potatoes less than before, clean the
rod, weigh the thing: 605.5, plus a tad.

Big Smile. Because 605.5 grams is what I've been chasing for the last
half hour, hiking back & forth between the sander - - a 'dirty' tool
not allowed to associate with lathes and the like - - and the Ohaus
triple-beam balance, trapped in its varnished cedar box over in the
corner with other Precision Stuff.

A stock VW con-rod is about 5.4" c-t-c. Forged from mild steel, its
weight may range from 505 to 550 grams. They are sold in sets
graduated by weight with a 10 gram variation across the set of four.
But for a good engine you want them to all weigh the same, or close to
it. The rods I'm working on today aren't stock. They are 5.6" c-t-c,
intended for use on a crankshaft having a throw of 84mm (stock is 69).

This is the fourth set of rods I've ordered for this engine. The
first three sets had been tampered with, probably by the clerks who
shipped them, so that the weight difference across the set of four was
as much as 16 grams. Since you can only remove about seven grams from
an H-beam rod, it renders them unusable in a properly built engine.
Which gets you a massive shrug from the people selling such junk.

This particular set of rods was ordered on 15 March from a retailer
less than a hundred miles away (G.Serrano in Torrance). After several
phone calls the rods finally arrived on 20 April. Fortunately, the
set proved usable but even then, the carton had been opened and one of
the rods removed from its protective wrapping. Had the set NOT been
usable it would probably have taken another month to obtain
replacements or a refund, which will help you understand why it has
taken FIVE MONTHS and three different retailers to obtain a suitable
set of rods for this engine. In one case I was forced to pay a 're-
stocking fee' even though the parts were not to spec. Air-cooled
Volkswagens are a vanishing breed and most of the remaining retailers
simply shrug; take it or leave it, we're only here for the money.

(So what to do? Buy your parts from Steve Bennett at Great Plains
Aircraft Company. He builds his engines differently from the way I
build mine but he's an honest person and you will benefit from
obtaining everything from a single source.)

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In the mid-1950's the Ford Motor Company published (in the SAE
Journal) the results of a decade-long test comparing the wear of
engines fitted with a full-flow oil filtration system to other
maintenance strategies, including frequent oil changes, by-pass
filtering and so on. Full-flow oil filtration was the hands-down
winner, reducing some types of wear by as much as 600%. Which is why
all modern engines are equipped with full-flow oil filtration.

All of the VW engines I've built since the late 1960's have been
fitted with a full-flow oil filtration system. This is accomplished
by blocking the normal output of the oil pump and installing a new
pump cover having a threaded fitting. The full output of the pump is
plumbed to a filter canister then returned to the engine via a
threaded fitting installed in the main oil gallery.

The VW oil pump can produce up to 300psi and a basic rule of
engineering is that the first thing 'seen' by the output of such a
pump should be a pressure relief valve, so as to protect the system
from excessive pressure. The full-flow installation in the typical VW
engine violates this rule since the filter canister is the first thing
seen by the pressurized oil. Since the typical oil filter bursts at
about 100 psi, starting a VW on a cold morning can be one HELL of a
mess.

(Yeah, they make high-pressure canisters... which typically cost $10
and up, when you can find them.)

In comparison to the connecting rods, finding a suitable oil pump
cover is a slam-dunk. I called Dee Berg, widow of Gene, chatted for a
few minutes and had a pair of suitable pump covers in my hands about
eighteen hours later. (Gene Berg Enterprises is even farther from my
shop than the outfit selling the con-rods :-)

Gene made his pump covers out of high-density cast iron that wears
even better than the stock VW pump cover. He also offered a cover
fitted with a ball-type pressure relief valve (GB-239x) that pops-off
at about 90 psi that has become the standard for all serious engine
builders. It costs significantly more than the bubble-pak'd cast
aluminum crap but it's money well spent. Not only will you recover
the cost by about the fifth oil change, the cover will last in excess
of 100,000 miles if treated with WSX (ie, tungsten disulfide dry
lubricant). By comparison, even when hard anodized an aluminum cover
will wear beyond spec in about 10,000 miles and show a steady decline
in pressure thereafter.

Before using the GB-239 I take it apart, clean it good and break all
the edges with a file. The socket-head screw securing the pressure
spring goes into the jig and gets drilled for safety wire. The sharp
edges of the outlet port are polished smooth then the Blanchard-ground
surface is burnished on a surface plate using #600 W&D flooded with
WD-40. After a careful cleaning the valve is re-assembled and the
flatted surface treated with WSX (ie, a Tech-Line product).

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The rain has turned into a steady drizzle, a welcome background for
the tick-tocking clock. The day has gone gray as I lock Mr. Ohaus
into his shiny wooden box, wipe down my tools and put things away. I
stopped building engines for sale several years ago, devoting more
time to horology, itty-bitty steam engines and black-powder, which
makes it kinda hard to explain why there's so damn many engines in the
shop. Probably because it's good fun - - plus, you get to go flying
now & then.

The coffee is hot in the house and there's a screen-full of mail to be
dealt with plus a pride of indignant cats pointing out that WATER is
falling out of the SKY and wanting to know what I plan to do about
it. Guess I'd better get busy...

-R.S.Hoover