Description
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
Kurt (verified owner) –
Got these for my 97 tj 3.1l stroker four banger. Was shorted 2 bolts but the hardware store had 2 5/16x18x1.75 inch grade 8 Allen heads. Installation was a breeze. Soaked the rockes for an hour in 10w30 brake in oil then swapped out the rockers. They fit with no modifications to the valve cover or breather tubes inside the cover. The fit is tight but so far no rubbing. I’ll take it apart in a couple days and look for marks. Power is a little better nothing to brag about but maybe in a few drive cycles the ecu may adapt more. It revs up in neutral twice as fast as it used to though. I have a head and intake that I ported and polished which I will be installing in a couple weeks hopefully that wakes it up more. I currently have a custom ram air scoop piped through the inner fender from the air trumpet on the factory air box to the spot between the bumper and fender, a polished 4.0l throttle with a matching spacer (which made a huge difference), my thinking is it smoothed out the map sensor reading as the 2.5l manifold vacuum pulses quite a bit. Also 4 hole larger injectors and deral electric fan. Exhaust back pressure is 4psi max.
So all in all they do help just not as much as I would have thought but still better. 😊
(NOTE FROM BOOSTED TECH: We did refund Kurt $5 for missing these bolts; we do our best to get it right 100% of the time, but if we don’t for some reason, we still aim to do the right thing!)