Trick Racing -- uh, Stuff

[Scott Fisher <sefisher@xxxxxxxxx>]

Chip Schug wrote:

>I am still trying to find the "right" cams or the right setup for that
>matter in my '79 2L Spider which I have rebuilt (over 2 years ago) with
>10.4 Borgo pistons, new racing valve springs, oversized valves in IN &
>EX, changed from SPICA to 40 DCOE Webers and all the other goodies used
>on a rebuild.  I went from the stock cam to the Columbo 11mm cam and am
>using the Marelli Plex ignition system.
>
>My Spider has a lot of "power", but I can not get the car over 100 mph
>without going over 5500 rpm in 5th gear.  

Because you're on the Alfa digest and not the Drab Econoboxes Owned By
Losers Mailing List, I'll assume that you don't expect to somehow
magically be able to go 100 mph at 4800 in 5th simply by rejetting your
carbs. :-)  That is, I'm assuming you *do* understand that there's a
fixed relationship between road speed and engine speed in each gear,
based on the final drive ratio, the gear ratio, and the tire size, and
that nothing you do to the ENGINE will make a difference to that
relationship.  Right?  Therefore, I'm going to assume that your
complaint is based on the difficulty your Alfa has in getting *up* to
5500 RPM in the first place.  Am I close?

One of the best engine tuners/vintage racers I have had the pleasure of
hanging out with, Tom Colby, was chatting with me once about how he
discovered the Great Truth About Tuning.  I'll quote Tom as closely as I
can remember it, even though he used a Bad Word (well, actually, two or
three):

"When I was twelve, I was really into slot car racing," Tom said.  "I
read every magazine, I read all the ads, I knew which motors were the
trickest and which controller and which brushes and tires and
everything.  So I saved up my pay -- I was a paperboy -- for weeks, and
finally had enough to go to the slot car store and buy *all* the trick
racing shit outta the magazines.  I put it all on my car.  Ran like
crap.  And that's when I learned that all the trick racing shit in the
world doesn't do a damn bit of good if you don't take the time to make
it work *together*."

This, of course, is also the origin of the now Usenet-wide acronym TRS,
which stands (in politer society) for Trick Racing -- uh, Stuff, hence
the subject of this posting.  

So Chip, here's what you have to do:

1.  Best bet: locate a chassis dyno within a hundred miles of your
home.  That's the most effective way to get your TRS to work together. 
Better still, find one run by someone who knows Alfas (and where IS
Charlie Rockwell when we really need him anyway?)  That way, the dyno
operator will know in advance what will happen if you dial the cams for
more advance or more retard, what will happen if you move up or down a
size on the main jets, the idle circuits, and the accelerator pumps. 
(If you can't find a chassis dyno, I've used a friend's Vericom
Performance Computer to test real-world, on-the-road horsepower; it has
a set of sophisticated accelerometers, clocks, and processors inside
which calculate horsepower per 1000 lb by measuring the acceleration
inside a moving car.  Pretty slick; not cheap, which is why I use my
friend's.)

2.  Second-best bet: find an Alfa shop with an exhaust gas analyzer and
have them check your mixture at the tailpipe.  This isn't as good
because it's not going to test it under load (as a dyno or Vericom
would), but it'll give you an idea whether you're jetted exorbitantly
too rich or too lean.  And if the shop really knows Alfas, they'll be
able to get you at least pointed in the right direction.  It may not be
optimized, but you may be able to get the idea.

3.  Third-best: get Jim Kartalamakis' Alfa book and Pat Braden's Weber
book.  And while you're at it, get David Vizard's "Tuning the A Series
Engine."  Yes, it's about a different engine.  Doesn't matter, the
wisdom contained therein will cause you to understand how all this Trick
Racing, uh, Stuff works together -- why cams work, what effect cam
timing has on where the power comes in, etc.  I'm sure you've heard the
old saying that knowledge is power.  It doesn't really register until
you adjust something that you've learned about and the car comes on a
lot stronger at a different point in the rev band than it did after you
just bolted something on and hoped for the best.

4.  Fourth-best: get a selection of Weber jets (mains, chokes, idle
circuits, accelerator pumps... what else?), in each of two or three
sizes up and down from the ones in your car now.  Then swap them in, one
by one (well, keeping all four chokes of your carbs the same, naturally)
and see which one works best.  Oh, and while you're at it, get the
cam-adjusting tool and time the cams a few degrees advanced and
retarded.  Don't go too far with the cam adjustment or you'll introduce
Mister Valve to Mister Piston, and they really don't get along.

Bolting all the go-fast parts to an engine (or a suspension, for that
matter) is only about two-thirds of the job, and should only use about
two-thirds of your money and time.  The last bit is the most important
part, and many a race has been won by someone who spent less on parts
and more on making the parts *in* the car work more effectively
together.

On the other hand, you could just go with my complete wild-ass guess and
retard the cam timing 2 degrees, go one choke size smaller on the
40DCOEs, lean out the main jets to the next smaller size, and tell us
how that works.  But that's just because it sounds from your list like
the TRS on your car was spec'ed under the ever-popular "if big is good,
then bigger must be better, so too big must be best" philosophy.  That
would be consistent with your complaint that the car has little or no
power under 5500 RPM; you probably have too much flow through your head
(uh, the CAR's head, that is :-) and not enough velocity at low engine
speeds to fill the cylinders well.  So drop the choke size to increase
low-end intake velocity, drop the mains to compensate, and retard the
cam timing to get the power curve to drop down a few hundred RPM.  BTW,
if anyone else is interested in *why* retarding the cam timing works,
particularly given what I'm guessing is wrong with Chip's setup, write
me; it's really very non-intuitive, and pretty cool. :-)

- --Scott Fisher
  Sunnyvale, California

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