what does nailhead mean?

im only 17 and i LOVE!!! muscle cars and whenever i get a chance i wanna learn more and more. so i was wondering why they call some buick engines "nailheads"?? -thanks alot.

It in reference to the Valves... they apperantly have a smaller than normal stem (still pleanty strong though) and sit straight up in the head... resembling Nails.

Excellent engines... common in street rods.. along with flat head fords.

i need help with the wiring color code for 2000 buick park ave rear amp too many colors dont know if i have them wired correctly