mr2guru

iTrader: (16)

Anyone running the new style yella terra rockers yet? They are supposed to be pretty light.

SPIV

My mechanic tested them in my built 346 and guess what at 6,600 rpm they valve floated like a mo fo. Went back to the stock rocker and no more valve float. I suppose that if you had lots of valve spring pressure then it would be o.k. but i like to have a very light weight spring,retainer & rocker combo.

mr2guru

iTrader: (16)

Interesting. They claim to be the lightest rockers out there with this new design. I know the older yella terras were nose heavy.

mr2guru

iTrader: (16)

Anyone else?

kenkaru

As I understand it, this means nothing if you don't post what springs were used. They do look A LOT lighter than the old Yella Terra's.
I don't understand why people keep blaming float on rockers. I think the aftermarket rockers are aimed at the super high performance market like 800+ hp. It seems like a lot of people who don't need aftermarket rockers are putting them on with springs that are just to wimpy and complaining about the float. I think I'm the 900th person to say this on the board. ...just thought I'd save someeone else the effort I guess.

SPIV

Cam is an XER 236/238, springs are Comp 918's. So when the rockers were changed back to stock suddenly the valve float was gone........So obviously over the nose weight is not as light as a stocker.

kenkaru

so I guess you're agreeing with me?

SPIV

The funny thing was that Yella Terra told us how the combo would be fine (note that we had the adjustable ultra lites) but...in reality it did not turn out so and we were forced to revert to a tried and tested combination of 918's & stock rockers. In fact I sold my original Yella Terra roller rockers because I knew that they were too heavy over the nose to work.

So there you have it.

kenkaru

That sucks that Yella Terra said they would be ok. I had my own bad experience with the YT's when they didn't fit under my perimeter bolt valve covers. I'm still a little mad about that.
I'm not trying to stick up for Yella Terra or anything I'm just saying that unless your revving to insane levels with crazy ramps, the stockers are fine and float is a result of the COMBINATION of a heavy rocker and a weak spring.

obZidian

iTrader: (2)

double post!!

obZidian

iTrader: (2)

I have been trying to find a definitive answer to this and seince the search function is fuzzy, i went back to page 40 and worked my way to the first.

I have a set of yella terra rockers, the old design. My cam is a XE-R cam @ 244/248 603/615 114lsa. My car is a 98, however, i couldn't use my 98 valve covers cause the bolt pattern on my covers didn't match the 6.0L lq9 heads. Also, my springs are ferrea eudurance duals rated at .670 lift.

Funny thing is that my rockers are making contact with these rockers!! These are the other type, bolts down the middle, and after a few tries, im gonna dremel the hell out of my covers.

This is the thing, when i originally dynod the new motor, the dyno sheet seemd' to show that this motor was exhibiting valve float. Later, i swapped out the springs, had four broken, and again the motor felt as if it still had the float from before.

AGAIN, i busted another spring, the SAME one again. cylinder #2, exhaust spring. I also found it interesting that most or all of the springs that broken before, were all exhaust springs.

But, now i have this srping that is broken and noticed the witness marks on the covers, telling that these rockers dont fit. The marks are deeper along the front, exactly over cylinder #2, where the same spring keeps busting!! So, far, this spring has broken twice. In less than 5k miles. No strip time, just some street fun.

My concern is one, are these rockers, while hitting the covers, assisting in breaking my srpings? These springs are pretty heavy, will find the spec sheet, and since it is stated that these rockers are top heavy, maybe that with the addition of the movement restriction from the covers could cause some nnecesary strain on the spring and blamo, it snaps under the pressure. Two, are these rockers, with my spring package, possibly causing the float?

On the graph, the first few graphs were with float (around 4900-5200), a flat spot to the limiter. However, and i think this is where a spring or two let go, the subsiquent pulls, the float continued but the power band just nosed dived around 5200.

Im a bit confused and since i now have the option to do somethign about it now, it would be great if someone could help me clear this up.

Thanks!!

leaftye

obzidian, your rockers hitting would introduce additional harmonics into your springs that'd cause them to reach the end of their fatigue life many MANY times faster than normal. It also just introduces more heat, and if it can't get rid of it fast enough, would cause it to break as quickly as it would take to heat up.

Jordan S.

iTrader: (17)

918 springs are trash, get better springs you wont float the valves.

For the record I had to clearance my valve covers to fit my YT rockers. Yea, gay. But with little effort I got them clearanced.

ZMONSTER!

iTrader: (9)

dude this thread was almost 3 1/2 years old when you posted, why the resurrection?

BigRich954RR

iTrader: (1)

WEll at least post a pic of old design and new design