I need a little wisdom with the replacement of the crankshaft on my
TR7...
My '79 TR7 developed a pretty severe problem with a warped head,
deteriorating rings and other general ignition problems. I came across
an '80 TR7 that had very poor body features, bad bearings and
(therefore) a damaged crank, but compression and ignition were near
perfect. So, I pulled the crank from the '79 and built it into the
engine from the '80. To select the proper bearings, I used plasti-gauge
to determine that the crank was .010-under. With the engine rebuilt I
installed it in the '79. I drove the car (very happily with
never-imagined power) for a little more than 2000 miles before it
developed an loud knock. I pulled the pan off and the #4 rod bearing
cap to find that the crank had BROKEN - it actually has a significant
crack in it that caused the bearing to be eaten down to the copper.
I bought a new crankshaft and am getting ready to install it.
Does anyone have any thoughts about why the old crank cracked? They're
one of the strongest components on the whole vehicle! I've considered
that I may have: chosen the wrong bearings; mis-aligned something in the
installation; torqued the cap down too much or too little....
I guess what I'm really after is: can you think of anything that might
cause this again that I can do or check before I install the new one?
Should I be concerned about the wrist pin(s)? If, so, what can I look
for?
Please help me avoid wasting a considerable amount of time and money.
Thanks,
Mark Pelzel
(direct at mark.pelzel@cexp.com or pelzelm@tusc.com)
'79 TR7
[son of '63 TR4]
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