Todd Mullins wrote:
>
> > I had hardened valve seats, stellite valves and bronze valve guides put
> > in and the whole lot balanced and "blueprinted".
>
> Please educate me: What is "blueprinting" an engine? I'm looking at a
> rebuild in a few years, and have already started thinking about the
> process. I basically know how to balance the reciprocating parts, but
> I've never heard anybody explain what "blueprinting" is.
>
> --
>
> Todd Mullins
> Todd.Mullins@nrlssc.navy.mil On the lovely Mississippi (USA) Coast
>
> '74 MGB Tourer
>
> "I could go at any time..."
I'm no expert, and I will post this reply to the list in case someone
can give you a better answer, but here goes---
"Bluprinting" is one of those terms that uninformed people (like me)
throw out trying to impress other uninformed people with their great
knowledge of car engines. In fact, the machine shop that worked on my
engine rebuild didn't even use the term. They instead told me exactly
what they were going to do, when I jumped in and said "Oh, is that what
you call 'blueprinting'?". "Yes," was the reply, "but we don't like to
use that term, we rather tell you what we are going to do to avoid
confusion and misunderstanding." I suggest you take the same approach
with any machine shop you use. Don't just say "blueprint it" but get
them to describe each thing they are going to do, its benefit and its
cost.
Generally, the term refers to the practice of bringing the clearances in
the engine to tolerances better than the factory could or would. As
technology has improved, the car factories have been better and better
about getting extremely high quality manufacturing techniques that have
reduced the clearances and amount of slop in an engine. The amount of
slop in an engine will affect both its efficiency and its durability.
For example, every time the crankshaft turns, the force of the piston
through the connecting rod slams into the big end bearing. If you have
a big end (main) bearing that has a lot of slop, then when the rod hits
the bearing it will hit with a force that will be partially absorbed by
the slop and by the bearing. This means that less of the energy is
available to turn the crankshaft and that the bearing wears out more
quickly. Instead, a bearing with no slop (for arguments sake) will
tranfer 100% of that energy to the crankshaft and thus to powering the
car. To take the other extreme (again for arguments sake), think of a
big end bearing with 1/2" clearance (instead of the millionths of an
inch that are used). Think of how hard the big end would hit the
crankshaft and how much energy that would absorb! The crankshaft would
turn slowly, jerkily, if at all.
As far as I know, this applies in one form or another to virtually every
place in the engine where one moving part touches another. In
blueprinting, all or most of these clearances are reduced to the closest
factory spec. Whereas when the car was built the factory would allow a
relatively wide tolerance, which means that any particular engine could
have clearances at either end of a fairly wide range.
Since blueprinting increases efficiency, it means more power and higher
revs, and it decreases wear.
I hope I'm not all wet with this, since its been seven or so years since
I redid my engine. If I am I hope the list subscribers will be kind in
correcting me, although I might deserve some ribbing for using the term
in the first place.;)
David Littlefield
Houston, TX
|