| From | Message |
sandman
Dodge Dakota
6/03/2001
11:02:18
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 Subject: Clearances on 4.7
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Message:
I was looking at the specs for the 4.7 liter engine. While chrylser is maintaining much more narrow tolerances (go/no-go) their bearing clearances are about the same as the 3.9. Remember that the clearance is the actual measure of empty space between the bearing and the part that oil must fillin. The tolerance is how close to spec these parts have to be inorder to be acceptable. I am bringing this up because the clearance of the bearings is what determines what oil viscosity is needed at any given temp. to fill the void between the moveing part and the bearing. Remember metal is not suppose to touch metal. The parts are suppose to be suspended on a cushion of oil. The smaller the clearance the thinner your oil can be and still seperate the parts. The clearance where not significantly tighter but the tolerances for the part is significant if the manufacture is actualy following their own guidlines. Have fun everyone.
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Doug
Dodge Dakota
6/03/2001
14:42:26
| RE: Clearances on 4.7
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Message:
Keeping in mind these are,if I can assume,cold tolerances and as the engine reaches operating temp these decrease due to expansion.This is why high performance and engines that run at high power settings continuously have larger tolerances / gaps if you like at the bearings.
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