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Old 10-24-2006, 08:45 PM
olddog olddog is offline
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Join Date: May 2006
Location: St. Louisville, Oh
Cobra Make, Engine: A&C 67 427 cobra SB
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For what it is worth, I'm in the process of pulling apart a 95 4.6 DOHC modular. I know, I know, it not an FE, but bear with me a second here, as it becomes relevant. I haven't got it apart enough to measure the bores, but there are no ridge lines at the top. This engine has 105K miles on it. By feel I'm guessing less than 0.010 wear as I cannot feel anything anywhere, and you can still see the hone lines. Here is where it becomes relevant. This is an aluminum block with steel sleeves. I think the steel sleeves hold up much better than cast iron. This is a plus for a modern aluminum FE block, assuming they use steel sleeves rather than cast iron.

Additionally aluminum conducts heat better than cast iron, so cooling and even temps are much improved. However with the aluminum there is much more thermal expansion (think 4 times not sure). In my mind a large aluminum block push-rod engine almost has to have hydraulic lifters. With solids the valves would be mighty loose cold. Also the main bearing clearances change a bunch from cold to hot on an aluminum engine. Warm up is even more critical on an aluminum motor.

Hope that gives some food for thought on aluminum verses cast iron.
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