1.6 or 1.72 rockers whats the difference

astronut1885 said:

Roller rockers are a great mod, they relieve valvetrain stress, lessen oil heating by friction, and free up horsepower. Ford used 1.6 ratio stamped rockers on our motors, so using a 1.6 roller will maintain your factory valvetrain specs. 1.72 rockers create a little more lift and duration by magnifying the lift of the cam a little more than the 1.6s This is calculated by taking the length of the highest part of a cam lobe from the center of the cam, and multiplying it by the ratio of the rocker. Basically it's either "xyz" lift x 1.6 or "xyz" lift x 1.72, where the 1.72 ratio will result in more lift. The higher ratio can be good good because it essentially "beefs up" your cam a bit, and allows your heads to breathe better. It does have a down side though. Ford engineered it's heads to run with 1.6 ratio rockers, so everything is made to those specs. running 1.7s puts a little extra stress on the valve train, and can lead to alot of valve guide wear. That might be acceptable if you want to rebuild your heads every two years, but most guys opt for 1.6s because the tradeoff isn't worth it. I myself run 1.7s on a set of prepped GT40P heads, and I love 'em. They give my cam a little more balls, and they free horsepower. I don't plan on running my heads forever anyway, so the 1.7s work for me. They were also available at the cheapest price through a friend, which helped. I have no valve clearance issues, and my combustion chambers are smaller than stock heads, I have a bigger cam, and the bigger rockers. Think about the tradeoffs- more lift vs. longevity, and decide which ratio you want. I believe stock and Ford Racing heads are pedistal mount, but I'm not sure of the thread size. Once you've figured out the numbers you want/need, pick a quality brand and go to town!

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