The following web sites provide very interesting info evaluating iron and aluminum heads:
http://www.kostecki.com.au/articles/iron_vs_alloy_1.html
http://www.kostecki.com.au/articles/iron_vs_alloy_2.html
http://www.kostecki.com.au/articles/iron_vs_alloy_3.html
Mark
5461 & 5481
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