<VV> spun rod bearing = dead con rod

[djtcz at comcast.net]

snipped and bottom posted 
============================================== 
----- Original Message ----- 

From: "Jedd Hebrink" < jhebrink at anvilcom.com > 
Subject: <VV> 66 Monza 110 PG engine knock - mystery solved 


snippety ------ 

............. I spun the #5 rod bearing. ................ 
The rod and rod cap as well as the crankshaft journal all appear to be 
unscathed. The bearing took the damage. My question is this: would it be 
wise to install new rod bearings (these were .020) and plastigage and see if 
they are within tolerance limits? .................................... 
As always, thanks for your advice. 
Jedd Hebrink 
======================================================= 
As always, Until the rod is measured this is just a guess, but The size, roundness, and taper specs for con rod big-end bores is pretty tight. 
Diameter within 1/2 thou, taper and bellmouth less than 2 tenths (0.0002"), out of round maybe 1/2 thou if the bore is lemon shaped, big across the parting face. 
Not really measureable with dial vernier calipers . 

I've seen a few spun bearings, and I don't believe I ever saw a bearing "spin" without wearing and distorting the rod. Rods whose bearings have spun usually are so distorted that they are poor candidates for rebuilding.