Yella Terra 1.7 Roller Lifters

[CobraMarty]

Does anyone have any real life experience with these lifters? How they work? Any improvements? Installation difficulties?

It will take a stock 96+ cam to: same duration but increase lift to .433"/440", which should be just under the limit of the stock springs.

On a stock engine with it's poor flowing head, it is debatable what it would do/add, but on a modded engine with bored TB, 99+ intake, headers and 2.5" cat back exhaust, I would think that it would keep the same overall power curve and it would raise it 5-10 across the whole rpm range.

The Yella Terras are expensive, about $475, but they fit under a stock valve cover and don't require a spacer or different valve cover.

Now on a short intake runner supercharged engine, I could only imagine what an extra .250" of lift would do. ?10-20HP/TQ?

 

[CobraMarty]

Sorry, meant rockers. I was tired when I posted this.

 

[Talyn]

I could only imagine what an extra .250" of lift would do.

You mean .027"?

 

[CobraMarty]

Sorry, meant rockers. I was tired when I posted this.

Like I said I was tired when I posted, I meant .025". Thanks, a quarter inch more lift- that's wishful thinking.

Actually it is-

'96-'04 I/E= 0.408"/0.414"@1.6 >> @1.7= 0.4335/0.440, diff= +0.0255"/+0.0260"

'87-'95 I/E= 0.424"/0.424" @1.6>> @1.7= 0.4505/0.4505, diff= +0.0265"/+0.0265"

So anyway, Does anyone have any real life experience with these Rockers?

 

[Johnnie Walker]

Jegs has some HS 1.6 rockers..
http://www.summitracing.com/search/...er-Arms/Make/JEEP/Engine-Type/L6/?Ns=Rank|Asc

 

[Empty_Pockets]

I have them in my camaro, some of the best rockers you can buy. They had a production issue with the early ones so be careful if buying used...not a part you want to cheap out on

 

[CobraMarty]

Nobody has used these in a 4.0 jeep?

 

[Empty_Pockets]

NASCAR and other race series in Australia use them. I would recommend them for anything, no issues with mine, just set them up according to the directions and torque them down.

 

[Talyn]

Nobody has used these in a 4.0 jeep?

Nope, might want to check again next week.

 

[CobraMarty]

Are they 1.6 or 1.7?

 

[seanyb505]

Would any particular day work best next week?

 

[Talyn]

1.7

 

[CobraMarty]

What cam and springs are you using? Will the 1.7 also increase the spring pressure at full lift? and will that be a problem with the lifters or the cam lobes?

 

[Talyn]

What cam and springs are you using?

coil springs and a flat tappet cam

Will the 1.7 also increase the spring pressure at full lift?

Is the spring being compressed more at full lift?

and will that be a problem with the lifters or the cam lobes?

hmmm... maybe

 

[CobraMarty]

Did you have any 'noise' ?tapping sound on start up after you put these rockers on until the lifters 'pumped' up or readjusted themselves? Did you need to use just the one spacer or did you need both?

I read somewhere that when you remove the stock rockers and 'release' the pressure on the lifters, that when you reinstall the rockers and start the engine up that there is a bit of 'racket/noise' that occurs until the ?air is pumped out of the lifter and the lifter gets oil to repressurize and re-adjust.

Any cam specs? lift, duration? and spring specs? brand, strength, opening pressure at stock installed height?

Sorry for all the questions but it always seems like whenever 1 thing is changed, in this case 1.7 roller rockers, it effects 3 things down the line and then they also require attention.

 

[Dr. Dyno]

Nobody has used these in a 4.0 jeep?

Yes, I have them in my stroker but they're 1.6 ratio.

 

[CobraMarty]

Do you think that the additional lift on stock valve springs will 'fatigue' them and lessen their spring rate?

 

[streetxj]

^I guess it depends how heavy your right foot is. :laugh3:

 

[offroadordnance]

www.enginebuildermag.com article 1251 answers almost all of the questions asked and gives some options to increase stock spring life such as cryo treatment to increase spring life.

 

[merdock69]

http://www.enginebuildermag.com/Art...r_arms_valve_springs_retainers_and_locks.aspx

Here's a link to offroadordnance's article reference.