1.6 to 1.7 roller rocker conversion's

[Raceghost]

Is there anything to be had in doing this to 4.0L
I read somewhere that the stockers are 1.6.
I found a nice set of 1.7's and was wondering if I would gain performance?
Currently my Jeep is running headers, or a full exhaust, I will be adding a bored TB, MSD 6 Offroad ignition, and intake of some sort...
Thanks in advance.

 

[seanyb505]

What brand are the rollers?

 

[Raceghost]

I am not sure, there is a couple on line. Any peticular line thats better than others?

 

[seanyb505]

Ive been told the 1.7 might give a little more lift... where are they online? I was advised to go with Yella Terra, you can order them from quadratec.

 

[Dr. Dyno]

Is there anything to be had in doing this to 4.0L
I read somewhere that the stockers are 1.6.
I found a nice set of 1.7's and was wondering if I would gain performance?

If the head is completely stock, the gain would be negligible despite the increase in valve lift from 0.424" to 0.450" ('87-'95 cam). Higher ratio RR's will produce a better HP gain on a ported head that flows more air at higher valve lifts.

 

[alex22]

Off on a tangent.... You could always port the head to flow great down low and use a cam with a longer duration at a shorter lift. This will produce a lower torque curve.
You could do a search for a thread on puting Big block chevy 1.73 rocker arms onto a 4.0 or stroker. but in the end it will probly cost you as much as a set of yella terra rocker arms.

~Alex

 

[Dr. Dyno]

Off on a tangent.... You could always port the head to flow great down low and use a cam with a longer duration at a shorter lift. This will produce a lower torque curve.

A 3-angle valve job improves low lift port flow and increases the flow area under the curve, which is good for low rev torque. A longer duration cam will hurt low rev torque 'cause it'll bleed off cylinder pressure. What's needed is a shortish duration cam with moderate lift so that you can use the stock valve springs/retainers.
A good combination for bags of low rev torque with decent HP would be the '96+ cam combined with 1.7 roller rockers. In a 4.6 stroker, this combo would make an XJ a lot of fun to drive.

You could do a search for a thread on puting Big block chevy 1.73 rocker arms onto a 4.0 or stroker. but in the end it will probly cost you as much as a set of yella terra rocker arms.

It will end up costing a lot more because of all the modifications you'd need to do to the head to make the BBC 1.7 rockers work. The Yellow Terrors will bolt on easily under the stock valve cover without any modifications, so you can do them in your own driveway.