If you wish to fit RB26 covers onto an RB25 or Neo, The VCT hub on the intake cam causes clearance issues with the RB26 cover. This can be fixed with the weld in VCT bump.

Made from 6061 aircraft grade aluminum, it is very light, easy to paint and will look perfect on your RB25 or Neo with RB26 covers.

Installation: You will need a 3" - 76mm hole saw to cut the hole for the VCT hub to poke through. To mark out the center of the hole, locate the yellow dots marked in the picture and draw a cross. You are advised to double check that this is center on your application BEFORE you drill the 76mm hole. We recommend using a 4mm pilot hole, and mark the center of the VCT hub to confirm center.

Once the hole has been cut, The VCT bump has a locating lip machined into it to assist with fitment, so simply pop it on. Then glue or weld the bump to the timing cover.
Finish the modifications off with a fresh coat of paint.