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With the stock setup, a cam gets dropped
into place, and that's where it stays. Mainly
because there are two bolt holes on the cam. These
bolt holes line up with the bolt holes on the cam
sprocket.
And that's the way it works.
This is sort of nice, if you assume that
cams are exactly the same.
But for that critical bit of performance,
a cam should be able to be individually adjusted to the
engine. Also, the performance curve can be
modified somewhat by redegreeing (again, an
impossibility with the stocker).
The secret bit on this is the special cam
drive gear which R.C. includes as part of the Cobra kit.
This has six holes, which gives the owner up to 14
degrees of cam placement, to adjust for shortcomings or
desired modifications.
Cam chain goes up in the air, cam gear
and cam go into place, after rockers and rocker shafts,
etc., plus the trick R.C. rocker stand supports go on.
Collins, by the way, doesn't recommend
lightening the rocker arms. That's a car trick,
and with eight or so cylinders, you get improved revs.
However, with only four cylinders, and rockers that are
already minimal weight, there's nothing but hassles to
be gained.
The rockers are, however, very closely
inspected by Moffet. One area he checks critically is
scuffing on the foot. If the hard chroming is worn off,
the rocker gets quickly junked out.
Once assembly of the upper end is
complete, Moffet degrees the cam.
First stage, of course, is making sure
that the valves aren't going to hit the pistons.
Old-time builders did this by installing a hunk of clay
on top of the piston, and then turning the engine
through. Then the head came back off, and the clay
was checked for any valve notches.
Moffet has a very simple comment on this:
"Stone age."
A much better way is by moving each
piston in turn to TDC. Then a dial indicator is
mounted on the engine (Moffet has a magnetic mount), and
the cam is set on an overlap stroke. The dial
indicator is set to zero, and then the rocker arm is
lifted with a screwdriver. He knows maximum cam
lift, and adds .050-inch. If nothing hits before that
reads on the dial indicator, he's home free, with no
muss, no fuss, no disassembly and reassembly, and no
clay gooping up the inside of his engine.
Now for degreeing.
Degreeing is, very simply, checking to
see that the cam behaves as it's supposed to, when it's
supposed to. Or, with the adjustable cam chain
sprocket, setting it where it's supposed to. |
Cylinder #1 is moved to TDC. He
sets a degree wheel and a pointer on the crank.
Then he finds the base circle - the point where the
rocker arm is on the heel of the cam, and the dial
indicator doesn't lift.
At this point, the dial indicator is set
to zero. The engine is then rotated through, until
the dial indicator indicates .100 lift.
At that point, the degree wheel on the
crank is checked. It should match the theoretical
cam opening point. The engine is rotated
again, and when the dial indicator returns to .100, a
second reading is taken. This should match the
specified cam closing point.
If not, the cam gear bolts are loosened,
and the cam is readjusted. That is the most complicated
and careful end of a very careful assemblage.
All of the information on the engine is
entered on a small card, which is shipped with the
engine to the customer. You then can tune your
engine yourself (or even take it to a dealer, hand him
the sheet, and any competent wrench should be able to
work on it).
The final step is putting on the
wrinkle-black valve cover, with large supports, and
cementing that brass plaque on either side of it.
You are now two grand poorer.
And you have your basic engine.
The engine, by the way, comes with a
Lockhart oil cooler. Collins has found this to be
the most effective cooler, and insists on its use.
There are now three options left to the
customer.
First is exhaust. With an R.C.
engine, by far the most logical thing to use is an R.C.
pipe. So you're out $140. The pipe, by the
way, not only works extremely well, but is well within
the legal parameters of most cops' ears.
That's simple.
The next choice is carburetion. For
several years, Collins was pushing Weber carbs.
The kit goes out the door for $350, complete with
manifold, linkage and all the rest.
It is easy to install, and works
exceptionally well. The biggest problem that might
be encountered is finding things like jets and such in a
non-urban area. The carbs come, by the way, very
close to correct. The most that is usually
necessary is to change the main jet size one notch. The
carbs aren't just shipped "as is" to the customer - R.C.
spends a good deal of time setting them up.
They offer several advantages, in
addition to looking evil. There is probably more
wide-open-power advantage to them than any other carb on
the market. Plus they are mechanically synched,
and don't require use of a vacuum gauge. |
However, there are several major
drawbacks. They can be hard to order - everything out of Italy these days is
questionable regarding availability.
Second, is, of course, the cost.
And finally is the availability of parts.R.C. has found, after extensive
experimentation, that the standard carbs, with
modifications, work just as well for any sort of usage
other than wide-open competition. Since the
price of modification is only $95, this is something to
consider.
The final option is ignition. Stock
ignition simply won't work with the Cobra engine.
As any owner knows, Honda fires two plugs
simultaneously. One is just before the intake stroke,
one is on power. All well and good, with stock
cams.
However, with a hot-rod cam, the intake
valve is open when the coil fires. This can
partially fire the incoming mixture, and vastly reduce
the efficiency of the engine. Even an otherwise
excellent unit like the Sebring CDI doesn't solve this
problem.
Any system which retains the
double-firing of the coils will have this.
Formerly, the only solution was the ARD
magneto. This, though, has jumped in price to a
very healthy $249. The mag, also, can be back-ordered as
much as four to six months at any time.
The mag provides, however, a number of
excellent services. First, of course, is that all
four plugs are fired separately, which eliminates any
trouble with firing on the intake stroke. The ARD mag
eliminates the whole stock points, advance and coils,
and takes about five minutes to install on a bike.
It is a locked advance (normally at about 32 degrees),
and works extremely well. One tested by us gave
little trouble over 13,000 miles, in all kinds of
weather.
Collins is currently, though, finalizing
an ignition system for the street rider, which is
supposed to retail for around $159. It is a
Mallory competition distributor, which will include a
new transformer. It mounts on the points side, and
the rider can set advance and points curve on the item
with no trouble. The points can be replaced at any
speed shop, and the Mallory will also fire only one
cylinder at a time.
Those parts complete the Cobra engine.
With this, you now are going to become
the instant street or strip terror of your town.
You know, unquestionably, that you have the fastest bike
around.
For some people, that's enough to justify
two grand right there.
For any racer, the security of being
unbeatable is worth any price. It also is not a
bad way of paying for that Cobra engine.
And a Cobra is a very deadly animal.
One strike and you're gone.
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