150 HP LA 318 - vs - 230 HP Magnum 318

volaredon said

360 heads only serve to make an already low compression ratio even worse.

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Didn't say don't do anything about CR, a slight milling gets you 318 chamber size, or better yet use proper pistons. There's many ways to get there but starting with 5.9l/360 heads are gonna get you at least 40+ hp neverminded aftermarket ones. Why do think the factory did that with the 5.2l magnum, to get the power number up to match modern time power levels.

No matter what you do to 318 heads you can get better results doing similar with 5.9l/360 heads. Even if your goals are modest you'll need less cam to get there which will be more streetable overall. For the price/performance speedmaster should basically be the starting point for pretty much any build.