These 1.7:1 roller rockers will allow your Jeep, instead of falling on it’s face at 3800-4200rpm, to carry that out to 4600-4700rpm (right where the automatic transmission shifts at). This is a great option to squeeze more out of your stock cam, even without a supercharger.
These rocker arms have been specifically designed in conjunction with Harland Sharp to provide the correct geometry for the AMC/Jeep inline six cylinder engine family, including the 232, 258, and 4.0L. They provide an actual 1.7:1 ratio (over the stock 1.6:1), in addition to eliminating the loss of lift resulting from flex of the stock weak rocker arms. They will fit the ’91 and newer 4.0L head, and because they are non-adjustable, they are the only known roller rocker that will fit under the stock valve cover with no additional spacers required.
What you get:
- True 1.7:1 (if you have a more aggressive cam than stock, you should consider the 1.65:1)
- Fits under stock valve cover without a spacer (may require tiny modification to PCV baffle)
- Additional 2-3 degrees of duration
- Additional 0.025″ lift