Yella Terra 1.7 RR's

[WarShrike]

Just a thread to inform everybody in the market about these rockers. Here's a few things I've learned while performing the install on these rockers. I figured I'd post this up as the company informing the customer seems to be very lacking or it is not common knowledge to those here in the states.

I bought the Yella Terra Platinum adjustable roller rockers: Model #YT 6333

First off, the only thing they tell you about on the website is this:

Comments: Twin shaft adjustable 1.7:1. Drill and tap rocker pads to 7/16" UNC

There's alot more to it than just this statement.

Second, even with 0.020" milled heads, .045" Head gasket and running the S1X NA cam which should be close to a stock base circle, I need longer pushrods. How much? How about 7.430" or about .38" longer than stock. I expected to run properly sized pushrods anyway, but I figured I'd inform the public for those looking into something like this in the future.

Third, valve cover clearance. Yella Terra offered valve cover spacers a few years ago for these rockers but no longer offer them. Height is not just the thing to consider, these rockers are big honking pieces of kit. The stock rockers have an angle at the top of the head. The YT6333's have a flat head as they have an adjuster nut at the top. See pic:

With this taken into consideration, the stock tapered valve covers will not cut it even when using another valve cover flange as a spacer. I picked up scratch marks on my freshly sandblasted valvecovers right on the edge of the adjuster nuts and this hits right dead center of that tapered area. A US member has these rockers installed on her car and has a set of fabricated valve covers to allow for the clearance. Something many people don't want to do or are willing to spend the cash on it.

So with this you might need to look into wider valve covers that go all the way to the perimeter of the flange instead of inside the flange area and maybe with less of an angled taper. I am looking into this right now and will report my findings in this thread.

 

[Immortality]

bugger. have you tried posting in the YT sub forum in the sponsors section at the top of the main page? they are normally fairly good with there replies.

i guess those the joys of modified cars/engines. nothing is quite as simple as it first seems

 

[chargedvx6]

To the original poster. Your complaints may be warranted but keep one thing in mind. These rockers were deemed obsolete some time ago and were replaced by a much lighter an smaller bodied rocker called "Ultralites".

The only application IMO that these Platinum rockers would still be relevant are in a race only set up that has a solid lifter conversion done. In an application such as this (assuming it's an all out type of build) you would most likely have custom valve covers anyways to accomodate the rockers. The rockers were designed with this in mind and considering that the heads need to be tapped to take a larger thread I find your complaint abit out of proportion.................sorry but that's the way it looks to someone that knows a little bit about the product you are bagging.

You mention that longer push rods were needed? I would imagine that the S1X NA cam would have a reduced base circle of around 0.040"- 0.050" and considering you will be running approximately 0.523" with 1.6 rockers or 0.556" intake lift with the 1.7 rockers then different length push rods will most likely be needed. It's a no brainer really.

Not slandering you but when you go all out everything becomes a custom scenario as for what fits where and most of us learn the hard way.

I hope you upgraded lifters to OE-Rs (unless you actually have done a solid lifter conversion) as they will give you a great chance of acheiving a short travel preload on the lifters.

 

[WarShrike]

Running LS7 lifters, and I anticipated different length pushrods with the build.

I'm calm now lol! I'm not upset or anything I just wanted to get the information out there. I've got a set of valve covers on the way for $200usd so we'll see how that goes.

And thanks for the input chargedvx6. I just find it frustrating sometimes that it is so hard to get any information on some of the products without it becoming a wild goose chase. I spend all day researching an item that takes all of 30 seconds to order lol!

 

[chargedvx6]

Cars are a head ****, that's for sure. I realised once you deviate from the OEM set up all the rules can quickly go out the window. That's where the real learning starts:beer chug:

LS7 lifters are the same as LS1 lifters aren't they? LS1 lifters are the same as V6 and so on and so forth.

 

[WarShrike]

Yeah, this is a learning process. You mod one part and find another part down the line that won't cut it anymore, won't fit properly again or interferes. I've been replacing parts as time goes on because I've found things here and there that just aren't going to be up to snuff.

Car is going to be brand new mechanically once this thing is done...

 

[westerlybreeze]

YT Platinum Roller rockers

Hey there, I used a 1.6 ratio set and discovered everything as in the first post :doh:

Here's a bit of what I've done recently..

I've got a mechanical profile cam (0.100" reduced base circle - regrind), I brought a set of Alloy Rocker covers with spacers from Ozzie (- to clear the rockers),
I used longer pushrods and spent time spacing the rocker pedestals (getting the right height for rocker tip wipe over the centre of valve stem head).

Redrilled to 7/16" rocker pedestals and had to use 200lbs seat pressure springs for Solid roller profile cam

I also used a set of Ferrea LS1 SS valves (Inlets turned down, exhaust are same size), which are slightly longer than the Stock V6, but same 8mm dia stem.

Top is stock Hydraulic Roller for L36/L67 V6 and LS1.
Lower is Comp cams 8956 "Endure-X" Solid Roller lifters (these have oil feed to the roller for street use) and I Shamphered the edge of the pushrod cup oil feed hole - as the V6 oil gallery is on opposite side to the LS1.

And here fitted to the block with "Link bars".. (I cleaned the valley better before putting manifold on.. Honest!)

:mods: