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:
1. 1.6 or 1.7 lift?
2. Adjustable or non adjustable?

 

I would likely want more lift if using the stock cam.

 

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.

 

If i recall correctly the adjutables dont fit under the stock valve cover. Feel free to correct me.

 

1.7:1 non adjustable.
will work with stock cam, valve springs and pushrods and fit under stock valve cover.
I use Harland Sharp exclusively. Don't know about Scorpion.
Adds 0.025" lift and 2-3* duration and about 10hp across the whole power range and extends power especially over 4000 rpm to 4600 rpm.

 

Listen to Marty^^^^

 

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.

 

Just dropping in a different cam is not all that easy.
You need new new timing chain lifters, different length pushrods, new upgraded valve springs, and still should use roller rockers for all their advantages, and then you have to break in the cam without flattening a cam lobe.

No thanks.
Stock cam and valve train and add 1.7:1 roller rockers and be done.

 

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.

 

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.

 

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.

 

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)

 

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
1.6 rockers
260° advertised duration
230° duration @ .050
.400 lift

Same cam with 1.7 rockers
260° advertised duration
235° duration @ .050
.425 lift

 

Is there anything needed to do like calibration to the Cam Position Sensor after 1.7 non-adjustable Harland Sharp roller rockers? Having some issues with that sensor possibly lately even though it's new with the distributor after the install of rockers, banks header, bored throttle body, & cowl intake.