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Old 09-07-2010, 06:02 AM   #48
Kevin in NJ
Senior Member
 
Join Date: May 2010
Location: South East NJ
Posts: 3,398
Default Re: What is average highway speed for the model a?

It is not stressed so much by RPM. The stressor is imbalance and lugging.

The bearings really do not care have fast the crank is rotating. The journals are just riding on the oil and not really touching any metal. The problem is when the system is run off balance. You get the engine off balance from a physical imbalance say from a crank out of center or dynamically out of balance. You can also get out of balance when you are lugging, which I am out of the correct words to describe, but the common example is when you are in too high a gear for the speed. You can also be lugging the engine with the wrong timing setting at higher speeds.

The A should always be run at higher RPMs and you need to take time to understand the proper setting of the timing where the engine is happiest for the given driving conditions.

Keep in mind that an engine that is built out of balance will seemed stressed pretty easy as it is just not working right. By out of balance, I am being very general and including items like not breathing right because the valves are not letting it breath right.
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