[Xack]

A '68 460 is pre-emissions restrictions. Up to '72 have higher factory horse power capacity. Normally, the D0VE, known as "DOVE" heads are the most desirable. These heads, refered to as "DOVE" are usually 68-71 style and are very similar. These can be identified by marking on the head and by type of rocker arm mount. These engines had higher compression ratios up to 12:1 factory. The 68-70 Thunderbird had 385 series engines, 429's marked on the air filter cover with "ThunderJet". These older heads have a lot of metal and can easily be ported to breathe better. '72 and later models had to conform to EPA emissions restrictions and therefore had lower HP. Also after 72 the HP calculation was modified. HP Values are stated lower, but overall the power is actually closer than the numbers tell. 72 and later models had lower compression ratios and therefore somewhat lower HP.

My Cobra has '68 stock C8VE heads on a 460 from a '68 Lincoln. I replaced the flat pistons with dished type and reduced the compression ratio to run today's ethenol street grade corn fuel. It has plenty of power for this light car and it sounds fantastic. Later I may replace the heads with Edelbrocks or Kasse later to remove some 150 lbs of the weight.