[xk-engine] Re: crankshaft radius


The crank can be turned further than -20 thou. -40 thou is the usual
limit although some will stretch it to -60 thou (not me). Check to see
if a -40 thou turning will allow the radius to be restored. Otherwise
you will need a replacement crank (any 3.4 or 3.8 crank will do). Some
may recommend welding up the radii, but a replacement crank will be way
cheaper. The radiused join between journal and crank reduces the
build-up of stress at that location. A sharp join will concentrate the
stress at that location, often initiating a crack.

Dave Q.
Mk2 3.8
XK150S 3.4
(ex-Mk10 3.8)>From Don Dean

Greetings again listers, I heard this morning from the machine shop (the engine has been in since August). Most of the findings were expected, but a surprise was that a previous turning (to -.020) of the crank had apparently removed the radius. As a result a new crank is recommended. The shop mechanic tried to explain what this meant but it was early and I didn’t comprehend well. I’ll follow up with the shop but in the meantime, can anyone explain what a crankshaft radius is and what it does?<