Do yella terra 1.9.1 have any identifing marks on em? ,so you could tell if they were correct from wreckers/ swap meets ,etc?
Not sure, but you can tell the difference easily. See below.
YT by a coutry mile.
Also you can't mistake them;
VS
To The OP:
Yella Terra are completely different designs, they are a
Roller Rocker manufactured from lighter and stronger aircraft grade alloy, with a roller bearing TIP on them. (See the photo for the difference). At higher RPM's these
Roller Tipped Rockers aka 'Roller Rockers' apparently create less side load on the valves. ~ RUF 231
MACE, FIT etc, all use the stock 'Rocker' from the factory which are re manufactured with the heads/tips skimmed etc (and all the rest) to create the higher lift.
For a technical report on the differences between standard 'Rockers' and '
Roller Rockers' - see this article here
Roller Rockers vs Rockers
Talking to alot of modifiers and engine builders, most recommend YT products due to their obvious advantages listed above (being a stronger, lighter grade alloy, different design, true 'Roller' design which creates valve stability etc). If you are asking an opinion on which is better, I'm not going to say yay or nay to either, though if I was to buy higher ratio rockers it would be true
Roller Rockers. But I wouldn't be going down that road, I'd prefer a lumpier cam. The difference would be minimal on a stock V6.
Based on the above, the choice is yours.
All this being said though, I would go with a different cam before upgrading rockers. But that's my preference.