> No way I thought. Way......It was an MG
> Midget, about a 71 or so in quite good condition.
> THis just goes to show, MGs boldly go where no other cool cars have gone
> before.
The only thing that would have made that picture complete would have
been if they'd been using its battery to jump-start a Jeep. :-)
> Please explain exactly what engine blueprinting is??
Engine specs (or blueprints) include a range of tolerances for
various dimensions, weights, thicknesses, corner radiuses, etc.
During the manufacturing process, the various components of an
engine will be tested against these tolerances, some of which are
tight and some of which are loose. If you get an engine in which
all the components are at opposite extremes of the tolerance limit,
you're likely to have a less balanced, smooth-running, or even a
more short-lived engine than if all the components are produced to
the same end of the tolerance limits.
Essentially, blueprinting an engine means going through every
component and matching them up against the best of the two
dimensions listed as the upper and lower tolerance range, where
"best" means most suited to that part's specific task. That
is, if valve seats spec at 1.64" with a tolerance of +/- 0.05", then
you cut all the valve seats out to 1.69" to get maximum and even
flow. If the rod bearing journals are supposed to have a clearance
of 0.01" to 0.027", you do what Kaeding did to my crank and grind
them all to 0.01" for maximum smoothness.
Balancing rods, as recently described here, is part of this process.
On the angled big-end rods I put in my 18V motor, for instance, Kaeding
found a 25-gram difference between the lightest and the heaviest rod
in the set. They matched them all to within half a gram.
You do this for two reasons: one, it makes the entire engine run
much more smoothly, because every component is matched to the others
of its type -- all valves are the same height, all pushrods weigh the
same, all rods, pistons, etc. are the same so there is no unnecessary
roughness in the engine's operation. Reason two, however, applies to
performance: when you ensure the maximum dimension of things like
valves, camshaft lift, cylinder bore, compression, and the like, you
are more than likely increasing the engine's performance over the way
it was before blueprinting. You remove sources of drag, vibration,
and other hindrances to getting the most power out the back end of
the motor (or the side, in the case of the Mini, or the front in the
case of a Hillman Imp :-). The actual power improvements are proportional
to engine size (directly) and precision of initial assembly (inversely).
That is, blueprinting an Aston's engine as it comes from the factory
might net you 1 or 2 bhp if you're lucky, while blueprinting a Chevy V8
has been known to gain 40 to 45 bhp. (Yes, *really* -- this is the
accepted figure, or was a couple years ago, for a Super Stock Corvette
motor after blueprinting for SCCA Solo II competition. Makes you see
drug testing of factory workers in an entirely new light... :-)
In some racing classes (paradoxically, as a "cost-cutting measure"),
blueprinting is not permitted -- well, okay, so you don't pay $200 to $400
to have the machine shop grind all your bits. However, the way around that
is that the teams with the biggest budget simply sort through an entire
production run of rods, pistons, valves, heads etc. and pick the ones that
come the closest to optimum -- the lightest, the thinnest, the thickest,
the biggest, the smallest, whatever dimension is deemed most critical
to get the maximum performance out of that particular component.
(Wish I'd known you were going to Peru, Dennis, I'd have asked you to
pick up some chile pepper seeds that you can't get in this country...
did you eat any of the local uchus or ajis? Our Peruvian aji is
just *now* starting to ripen, and it's a race with winter to see if
the cold nights kill it before the entire pepper turns yellow.)
--Scott "Shining Path? Naaah, more like Incandescent Gullet" Fisher
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