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Harland Sharp Rocker Arms, Pedestal Mount, Full Roller, Aluminum, 1.6 Ratio, 5/16 in. Stud, 4.0L, Set of 12. Please Click on the "Read More" link for additional details about this item. Thank you, Summit Racing Equipment. The World's Speed Shop Since 1968. See details - Harland Sharp Pedestal Mount Bolt-On Series Rocker Arm S40196 Roller rockers for 4.0 Newbie Thread Starter
Join Date: Nov 2019 Location: Oslo, Norway Posts: 20 Year: 2000 Model: Cherokee (XJ) Engine: 4 l
I have a low mileage (86k) 2000 XJ with small modifications (Wiper mod, K/N filter, 62mm TB). I am considering the Scorpion roller rockers. Questions: ::CF Moderator::
Join Date: Aug 2011 Location: Prescott, Az Posts: 41,630 Year: 1990 Model: Cherokee (XJ) Engine: 4.0 I would likely want more lift if using the stock cam.
Junior Member
Join Date: Mar 2020 Location: Utahhhh Posts: 38 Year: 2000 Model: Cherokee (XJ) Engine: 4.7 stroker Quote: Originally Posted by Morten Hjorth-Johansen I have a low mileage (86k) 2000 XJ with small modifications (Wiper mod, K/N filter, 62mm TB). I am considering the Scorpion roller rockers. Questions: I would want 1.7 to get some more oomph out of the stock cam, but that's me. If you aren't using a stock cam then just take into account that your cam specs will be impacted with a change in rocker ratio. As for adjustable or not I have no clue. I'm building a 4.7 now and I haven't gotten this far yet because I am blowing most my money on forged pistons and bushed rods. Valvetrain upgrades will have to wait for me. CF Veteran
Join Date: Mar 2015 Location: Northern CT Posts: 1,104 Year: 1995 Model: Cherokee Engine: Turbo 4.0 If i recall correctly the adjutables dont fit under the stock valve cover. Feel free to correct me. CF Veteran
Join Date: Dec 2011 Location: PA KOTUFU! Posts: 1,776 Likes: 0 Year: 1998 Engine: 4.0L 162,000 1.7:1 non adjustable. ::CF Moderator::
Join Date: Aug 2011 Location: Prescott, Az Posts: 41,630 Year: 1990 Model: Cherokee (XJ) Engine: 4.0 Listen to Marty^^^^ Junior Member
Join Date: Mar 2020 Location: Utahhhh Posts: 38 Year: 2000 Model: Cherokee (XJ) Engine: 4.7 stroker Quote: Originally Posted by CobraMarty 1.7:1 non adjustable. That sounds like a worthy upgrade given that it should build nicely upon any other power enhancements you might have. My rebuild budget doesn't have enough more squeeze after the stroker parts and I'll be using my stock cam. I would love to upgrade to 1.7:1 rollers, but I really wish they were about $100 less expensive. Oh well I guess it will be a coin toss if I want to pull the head and do a new cam later or just pull the valve cover. CF Veteran
Join Date: Dec 2011 Location: PA KOTUFU! Posts: 1,776 Likes: 0 Year: 1998 Engine: 4.0L 162,000 Just dropping in a different cam is not all that easy. No thanks. Junior Member
Join Date: Mar 2020 Location: Utahhhh Posts: 38 Year: 2000 Model: Cherokee (XJ) Engine: 4.7 stroker Quote: Originally Posted by CobraMarty Just dropping in a different cam is not all that easy. No thanks. Those are some of the reasons I was wanting to keep the stocker. Probably more power to be made with an aftermarket cam, but also probably safer to stick with the
stocker. CF Veteran
Join Date: Dec 2016 Location: SoCal Posts: 3,303 Year: 1987 Model: Cherokee (XJ) Just want to throw this out there. Increasing the rocker ratio does not increase duration. The only way to increase duration is to get a cam with more duration. All higher ratio rockers do is add a bit of lift. CF Veteran
Join Date: Dec 2011 Location: PA KOTUFU! Posts: 1,776 Likes: 0 Year: 1998 Engine: 4.0L 162,000 When 'duration' is measured at 0.050" lift, yes changing rocker ratios does change the duration as seen at the valve, and that is what we really care about. Duration of valve lift opening and how much the valve is lifted. The following users liked this post: CF Veteran
Join Date: Dec 2016 Location: SoCal Posts: 3,303 Year: 1987 Model: Cherokee (XJ) Marty - I do agree with you on the @ .050 measurement. But we both know that's not the real measurement. It's just a general measurement to give you an idea on what the ramp rate is. The valve is still going to start opening and finish closing at the same time though. But yes I get what you mean and do agree. Junior Member
Join Date: Mar 2020 Location: Utahhhh Posts: 38 Year: 2000 Model: Cherokee (XJ) Engine: 4.7 stroker Quote: Originally Posted by 5-Speed Marty - I do agree with you on the @ .050 measurement. But we both know that's not the real measurement. It's just a general measurement to give you an idea on what the ramp rate is. The valve is still going to start opening and finish closing at the same time though. But yes I get what you mean and do agree. So the valve does or doesn't stay open longer with an increase in rocker ratio? (ie 1.6:1 to 1.7:1) CF Veteran
Join Date: Dec 2016 Location: SoCal Posts: 3,303 Year: 1987 Model: Cherokee (XJ) Technically speaking, from the moment the valve starts to open to the moment it is fully closed, no matter the rocker ratio, it will be open the same amount of time. What Marty is saying is that most people go by duration when @ .050" of valve lift instead of actual cam duration. So let's just say you have an actual 260� duration cam. At .050" it's only going to be 230� duration. So when adding in the higher ratio rockers, the cam doesnt need as much lift to get to the .050" # which means it will happen sooner and take longer to get back to when the valve is. 050" before closing, therefore, you have increased the duration. Adding the 1.7 rockers would take that actual 260� cam and turn it into a 235� @ .050" cam. Here would be an example of the difference Same cam with 1.7 rockers The following users liked this post: Thread Thread Starter Forum Last Post .:. Wanted 1 07-13-2019 10:50 PM Cummins93 Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here 2 06-17-2018 06:49 AM xfact0r3 Stock Grand Cherokee Tech. All ZJ/WJ/WK Non-modified/stock questions go here! 11 04-07-2014 04:02 PM freegdr Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here 7 10-24-2010 10:32 AM Currently Active Users Viewing This Thread: 1 (0 members and 1 guests) |
Jeep 4.0 1.7 rocker arms
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