manzo81maro

Hey guys,

Long story short...just did a H/C/I build on my SBE LS1, put about 1000 miles on it, mixed driving (cruising/spirited driving/couple track days)...cruising yesterday @ 1500-2000rpm and engine suddenly developed a loud ticking noise, turned into the sound of something breaking...pulled over, got it towed home, discovered #7 cyl exhaust rocker arm broken...





Pushrods look mint (manton 11/32"), don't have the heads off so can't see the lifters (johnson short-travel linkbars), rocker bolts found nice n tight... so valvetrain got sloppy somehow, just not sure yet if the rocker arm yielded/failed or if a lifter collapsed...

I'm in touch with Tony Mamo who spec'd the build, but would also like to hear thoughts/experience from you guys...

Burken01

iTrader: (88)

Yikes

Are these the regular Yella Terra's with 8mm bolt?

Did you buy them new?

They look like the current revision vs the 1st generation which were known to break..

DietCoke

iTrader: (18)

They all break. Put stockers back on and enjoy the HP you gain

manzo81maro

10mm rocker bolts, brand new

Jontall

It looks like Yella Terra still has problems. Get them on the phone, because they should replace them all for free.

Burken01

iTrader: (88)

Damn, I know with the short travels you don't have much room for error on PR length.

So I'm assuming you measured for each PR, and didn't buy a 1 size fits all?

manzo81maro

Yes ended up with 6 different lengths of pushrods, ended up with a 0.003"-0.005" tolerance for 0.037" lifter preload

Burken01

iTrader: (88)

I'm interested to see how the lifters/cam look after you pull the heads.. If you pull the heads..

I know yella terra has had a fair share of problems, I was hoping the new style with 10mm bolt fixed that.

manzo81maro

I've read the same...I'm waiting to hear what Tony has to say...I will probably end up pulling head to see what the lifter/cam lobe looks like for peace of mind...really hoping it's a defect in the rocker and throw on a new arm or set of arms under warranty and be done with it...we shall see...

Burken01

iTrader: (88)

Yeah hopefully it's an isolated incident, this is the first time hearing about the 3rd revision of yellas breaking.

Let us know what tony says, I'm curious

ctd

iTrader: (1)

I was headed to set #3, always doing something wrong on my part according to YT. I'm quite fussy with valve train setup.

No YT's for me.

Jontall

Yella Terrors.... FTL.

corvet786c

iTrader: (6)

That same thing happen to me about 7 yrs ago. Put the stockers back on and get the brian tooley trunion kit. It gives the stock rockers more movement.

5_litre_eater

I'm running a similar setup. Have about 800 miles on these rockers, so I'm curious to see your outcome.

What are the cam specs? How much lift? Do you know how much you shimmed the rockers?

Darth_V8r

iTrader: (4)

11 months DD on mine

Burken01

iTrader: (88)

Your running the YT pro 10mm version as well?

So is the "pro" basically a YT ultra lite with 10mm bolt upgrade, or is it a new design non ultra lite..

Darth_V8r

iTrader: (4)

I am running the 10mm. I don't honestly know if there are other differences or just the bolt size.

Burken01

iTrader: (88)

You mentioned 11 months DD, how many miles is that?

I'm getting the same rockers for my Mamo heads so I'm curious, I don't expect them to be as durable/longevity wise being aluminum as a OEM rocker.

However I also only plan to put 1k-2k on my engine a year anyway, so I'm aware of the trade off.

manzo81maro

Cam is 227/231 .610/.614 114+2 LSA
Rockers were shimmed 0.075" for optimal wipe pattern, and pushrod length spec'd accordingly

manzo81maro

I was unaware there was a trade-off buying these rocker arms, pretty disappointed...I did not compromise on this build, went all out with everything...I would expect these things to outperform and maybe even outlast the stockers for the price you pay, not just be 1000mile disposable...guess it don't work that way with these...would be a big pain to go back to stockers as I'll most likely need to measure for a new set of pushrods as well, which weren't cheap either

Mamo will be sending me a new arm shortly, so I'm assuming it was actually just the rocker that failed and it's common...guess I'll know right away when I fire it up, if she's nice n quiet, safe to assume lifters are good....just kinda sucks now, gonna feel like I'm just waiting for another one or few to let go