That limits how many rpms that engine can take. A 216 with a 4.57 shouldnt really be run over 50 mph for any length of time due to the lower oiling pressure. I never drove my truck over 50 before switching over to the 3.55 rear.
You could really tell from the feel of driving her and the engine noise that it was really unhappy at that speed with the stock 4.11. Even with a 3.55 I don't really drive over 60 if I can help it.
Driving at your speeds with a 4.57 was probably detrimental to the engine. Yes, a 4.10 would help. Some of the other guys can probably help better to determine what may have happened prior to tearing into it. The biggest problem with the 216's and the higher RPMS is that they used iron pistons and those things really abuse the babbit bearings. Switching over to aluminum pistons during a rebuild will help.
I don't know why in the hell the shop folks would tell you that valve guide issues would have been caused by the rear end. That seems ridiculous to me. Are you sure it was the valve guides? Even so, nothing in the valve train is gonna be screwed up by your rear end. Maybe it's something simple like it just needs a proper valve adjustment.
Did the noise come on all of a sudden pretty much as soon as you left the shop? Did it get louder and increase with engine speed?
Jeff
