[DeTomaso] Crank Lightening

[tony DiGiovanna]

OK, so let's say an enterprising Pantera owner equipped with a Brigeport
Mill and a Colechester Lathe wanted to head in this direction (assuming he'd
leave the crank grinding and final balancing operations to the
professional.)  Where does one begin to collect the various acceptable (or
proven) dimensions for these mods?
  -----Original Message-----
  From: JDeRyke at aol.com [mailto:JDeRyke at aol.com]
  Sent: Monday, February 11, 2008 2:50 PM
  To: tonydigi at optonline.net; Detomaso at realbig.com
  Subject: Re: [DeTomaso] Crank Lightening


  In a message dated 2/10/08 7:47:12 PM, tonydigi at optonline.net writes:


    I don't know much about Crank Lightening.  Anybody care to share
generalities and Cleveland specifics?


  Significant lightening is gun-drilling the rod and main journals and
scalloping the crank flange between the flywheel bolt holes, but if this is
done along with reshaping the counterweights and cutting the journals to
Chev rod bearing sizes (more efficient oiling at very high rpms), you will
have to have the crank rebalanced. Note this is usually done with forged
cranks, although the stock cast 400 Cleveland crank had hollow rod journals
except for the back end of each hole whichs were left solid for some reason-
perhaps for strength in this truck engine. Note also that the lightening
holes are NOT drilled centered in the journals; if someone drills them
on-center, the drillings will break into the oil passages, ruining the
crank! This is not a home-shop mod!
  Pair this up with lightweight steel rods to save 1/2 lb apiece for 6" long
Chev rods with better angularity and a bit less cylinder wall drag,
lightweight tapered Chev wristpins (2 lbs less for all 8), custom forged
pistons to acxcept all this & clear Cleveland valves, an aluminum flywheel
and aluminum crank & waterpump pulleys. Doing all this can drop up to 20 lbs
off the reciprocating weight. The result will be an engine that gains revs
like a motorcycle! It will also gain horsepower and reliability with a
higher redline. This is such fun, you may wind up with excess traffic
citations!

  A stock cast crank weighs 52 lbs; a lightened and gun-drilled crank with
all the trimmings listed above will weigh in the neighborhood of 38-40 lbs.
Crank cost will likely exceed $2500 (rods & pistons extra). Note this is
roughly half the wt-loss and about half the cost of an aluminum block- and
it's still a Cleveland! Good luck- J DeRyke


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