What is the correct way to set Yella Terra roller rockers? Zero lash then half a turn?

You set them the same way you set regular tappets. Look in a workshop manual for the order to set them in, then measure the lash between the valve and the rocker with a feeler gauge and set accordingly. The standard measurement is .014. A lot of lumpy cams specify .016. Best to check what the cam spec sheet says.

Quote:
Where did that chunk of stupidity come from?
Why would roller rockers be regarded as being different from regular ones when it comes to valve lash?

A14force has got it exactly right, get the right specs & adjust accordingly.

The spec is according to the camshaft. If you are using a stock camshaft, use the stock lash specification.

Haha, the zero lash rubbish is how to get a rough setting for roller rockers on an LS1 motor.
I had set the clearance at 0.014 (hot) but was still getting a lot of valve train noise.
Might let it run a bit longer and have another crack.

zero-lash plus turn is how you set hydraulic self-adjusting lifters.

For "solid" (non-hydraulic) lifter like real engines have, it requires a gap adjustment.

Be sure to set it Engine fully HOT, and with a drag on the feeler gauge or it will make noise.

While on this subject how do you guys set the valve clearance.

As per factory manual - Piston 1 tdc on firing stroke set valves 1,2,3,5. Piston tdc on 4 and valves 4,6,7 and 8.

Or rule of 9 method ie.

Rotate engine until No. 1 valve is open and is just about to start closing, adjust the No. 8 valve <1+8=9>, Continue rotating engine until No. 2 valve is open fully then adjust No. 7 <2+7=9> and so on...

Any thoughts on the different methods?

Place No. 1 cyl on TDC of compression stroke. Both valves should be 'on the rock' [one just opening one just closing. Adjust valves of No.4 cyl.
Rotate half a turn, exactly. The valves of N0.3 should be rocking. Adjust No.2 cyl.
Rotate crank half a turn exactly.
The valves of No.4 should be rocking. Adjust No.1 cyl
Rotate half a turn exactly. The valves of No. 2 should be rocking. Adjust No.3 cyl

Two rotations, all done.

Whitesedan has got it. The "rule of 9" is increasingly more accurate as the camshaft duration increases (ie modified engines). It ensures that the follower (in OHV) engines is right on the heel of the cam, rather than potentially being partially up the ramp. This will be easy to see when you set them on your L-series as the relationship of the cam to the lash pad / rocker is clearly visible. The rocking valve method is quick and easy, but for performance engines a little more time & care will pay off with increased accuracy.