1969 351w heads vs aftermarket heads

after market heads walk all over stock heads, and the after market heads out of the box, will out flow ported stock heads, though the gap is much closer. your ported stock heads will add about 40hp over stock, which is about 10hp less than an after market head.

Not to mention better weight and less chance of detonation with aluminum heads

On a naturally aspirated engine, the difference in power is not that much, provided the '69 351W heads are fully ported with the bigger valves.

My brother and I have almost identicle 306 cubic inch engines equipped with dual quads. He built both motors. In an effort to avoid the amount of hours that he would have to spend on a pair of 351W heads for my combo, I bought a pair of 58 CC AFR 185's. On the dyno, his motor made 311 rwhp and 287 rwt, while mine made 307 rwhp and 278 rwt. As you can see, they're very close. Of course, if I were to add Nitrous Oxide, I would guess that I'd see more of a gain than he would. The aftermarket heads will allow more room to grow your combination.

jb1dsl said:

Not to mention better weight and less chance of detonation with aluminum heads

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But more of a chance to warp if you overheat it