Anyone know what the difference is between these? I have 1.8 ratio yella terra aluminum Roller Rockers on my L27, which is being pulled and replaced with an L67. Is there any way I can re-use the rockers? They use 5/16" studs...

To my knowledge they are totally different rockers that make them not transferrable.

Do you have any other details on that?

Only that if we check the part number or contact YT, that might give you more info. They are and have been listed seperately as S1 only rockers with vendors. I figure if they were interchangeable then S1 guys could use any ratio S2 rocker, right?

In theory, yes.

I checked the part numbers, and they are different, but the specs seem to be the same.

http://www.kustombitz.com.au/UserFil...tion-guide.pdf

They are both 5/16" studs, with a bolt on pedestool fitment.

I'm very tempted to take off the fronts and try to bolt them onto my sister in law'* L36, or at least compare the two.

The part for part comparison is now the YT 6659 and YT 6625...

Found some more details...

http://www.kustombitz.com.au/UserFil...pare-Parts.pdf

I think it is possible as long as your geometry is in check:

http://www.fullthrottlev6.com/forums...ad.php?t=58149

I can't check exactly all of the geometry, but the first thing I noticed is the height from base.

On the S2 Rockers (6625), the pedestal part number is 6559, which has a base to height of 11.40mm
On the S1 Rockers (6659), the pedestal part number is 7001, which has a base to height of 13.60mm

The trunion and bearings, shaft and bearings, bearing, and roller and pin are the same part number. The pedestal height difference is 2.2mm, which is almost negligible considering the amount of room there is to work with in the lifters. Correct me if I'm wrong there.

Now I need to find information on the arms. The arm ID number for the S2 is 5R, and for the S1 is 6Z, but I can't anything on them.

The lifters can compensate for 0.015", 0.02" max. That'* 0.381-0.508 mm.

If it'* too high, you may be able to have the head'* pedestal'* machined down to correct the geometry. If they're too low, that'* easier with spacers.

If you have proper contact with the valve, you may just need different length pushrods.