The ONLY Mustangs to ever get the 302 4v heads was the '68 J codes. So if your car is not a J code, you would only have the J code heads if someone swapped them on. If your car IS a J code, odds are good you have the J code (4v) heads.also, im not sure if these are original heads or nopt, but they are on my '68.
That was true in '65-'67, not true from '68 on. In '68, the blocks were the same (that I'm aware of), but the J codes got the 4v heads. They have much smaller combustion chambers, and the larger valves (not 351w larger, but larger than the 289 heads). This made the J code heads some of the best SBF heads, "back in the day".They have the same heads on 2v and 4v carbs. The only difference was carb and compression which was cause of piston and not heads.
Depends ... The 289's from '65-'67 had 1.67/1.45 valves and 54.5cc chambers. In '68 the 289 and 302 2v heads had huge 63cc chambers (low compression), and the same small valves of the 289 (basically the heads are dogs). Starting in '69, the cumbustion chambers stayed the same (63cc), but they got larger intake valves (1.78). The '68 J code heads were the first to get the larger intake valve, but had small, 53.5cc combustion chambers ... smaller than the original 289 heads. This gave the '68 J codes bigger intake valves and more compression than any factory 289.1968 heads were practically the same at 289 heads right?
That's only the J code heads (4v) and '69/later. '68 289 and 302 heads were the same ... small valves and large combustion chambers. Ford improved on them in '69 (second year of the 302).My "head chart" shows all 302 heads to have 1.78" intake & 1.45" exhaust. Maybe it is not totally accurate.