I still have my head's ,and intake from my '68 ,I'd look it up my self if I only knew where, is there any difference, or advantage to these head's ,as to a C code ,or were all small block head's ,289 ,302 equall? Thank's
The 68 J code heads are virtually the same head as the earlier 66-289 heads. Same small chambers, valves, ports. Only real difference was the round pushrod holes, where the 289 heads had pushrod guide slots. The J code head also used rail rockers and longer valve stems.