Looks like this has been out for a little while but I just came across it I'm going to investigate these some more on Monday

In stock form, Chevrolet’s workhorse “big block” is great, until someone tries to add a performance-enhancing camshaft. The non-adjustable rocker arms that lend themselves so well to low maintenance and longevity are suddenly a handicap.

For some time, Crane Cams has produced an ingenious yet simple solution – screw-in studs to convert Gen V & VI 454-502 Chevys to roller rockers. This change allows for and lends itself to any number of valve train modifications from higher lift camshafts to higher strength valve springs. Now, Crane has produced a similar stud to convert Chevrolet’s 2001-up 8.1 litre as well.

This unique high quality, low-cost rocker arm stud (part no. 99155-16) replaces the stock stud in 8.1 litre Chevys without tapping, machining or even removing the cylinder heads! The 10mm thread on the bottom end of the stud screws directly into the head while the 7/16" thread on top accepts any adjustable Chevy big block rockers such as Crane 13744-16 Energizer® or Crane 13750-16 Gold. Factory pushrod guideplates must be used to correctly align the pushrods. Heat-treated Crane pushrods (part no. 26640-16) or 3/8" diameter stockers from an 8.1 litre Chevy V-8 must be used as well.

Tom

 

so the 8.1 has FACTORY screw in rocker studs ???

 

Didn't really notice this when I took an 8.1 apart a few months ago but it sounds like they are.

 

I talked to the guys at Crane Cams this morning. This is a pretty easy upgrade that will allow you to use 1.7 ratio roller rockers (1.7 non-rollers come from the factory). The 8.1 comes with screw in studs so it's just a matter of removing the factor studs, cleaning out the holes, install the new studs and then bolt on a set of roller rockers (13750-16 is the part number for the Crane Golds). The Tech @ Crane quoted a 22hp improvement by switching over to the roller design. I thought that was a little high but we'll see. I should have a set here in a few days.

Tom
www.tbyrnemotorsports.com

 

Well, for the guys thinking about doing this I can tell you that it will be an expensive mod in the end. Crane didn't say that the rockers wouldn't fit under the stock valvecovers So... I had to locate a set of billet aluminum spacers to get enough room under there (read - $). I'll have those in the morning.