20141125231318 1 #102 1977 XLCR thunder heads rebuild XL 1000cc sportster Harley ironhead aluminum tatro machine see the rebuilding of a set of rare aluminum thunder heads for your 1000cc ironhead sportster. these XR750 style aluminum heads were made in the late 70's and early 80's. they turned your 1000cc sportster into a hotrod without doing anything else. no one just did these heads, they always did a lot more to really make your sportster into something different and very fast. no parts are available so I had to make all the replacement parts to do this rebuild. Manley made the special sever-duty stainless steel valves and I machined the cast-iron sportster kibblewhite valve guides to fit. after that it was more or less a regular rebuild. check all the clearances and make it all fit. tatro Tees, Hoodies, Hats, Parts at : tatromachine.com