[BobDuncan]

I have a 65 389 with yf code, I know this is not a GTO engine, but as far as I can tell is a 325 HP big pontiac engine. From what I have seen in the literature, when these different engine applications are discussed with different HP ratings, they are at different RPMs, so my question: is there really any difference between this yf and the GTO version of a 389?

thanks, Bob

[Uprmich]

Bob, unless I am off the mark, it is essentially the carb/intake and cam that make you see significant differences in HP and where it is achieved. Most of the D-port stuff is basically the same, assuming valve sizes and chamber sizes are equal. At least that's my opinion.