| Re: 302 failure - any opinions???
Julian, there is another 'cause' that can lead to this type of failure & its not oil surge related.
If your 302 still has pressed pins and it experiences any or a combination of the following conditions it will fail the rod bearings.-- High RPM leanout, Detonation, over advanced ignition, fuel quality, coolant temparature shocking, air locks in cooling system, sticking thermostat, heat range of spark plugs. --- If any of these are likely particularly in a track day situation with short warm up etc or your first time out the piston pin can partially seize in the pin bore, this in turn creates extra load/heat at the rod brg and if use is continued bearing failure or rod breakage results.- Why #1-5?, being at the front they experience any 'cold' coolant from the radiator first and due to the fireing order/air flow dynamics in the intake manifold #5 is known to be the 'lean prone' cylinder in Fords, now if the piston has expanded from any of the above conditions and the cylinder suddenly gets hit by a dollop of cold coolant it literally shrinks to the point where there is a seizure of the piston which is enough to cause the pin & rod bearing oil film to fail & start this destructive path.
Moral of the story-- look very closely at the piston pins/skirts for any sign of galling or overheating on teardown.
Jac Mac |