[DeTomaso] Crank Lightening

[JDeRyke at aol.com]

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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