There has been a change to the Model Block Bore size to create a secure fit around the Power Pack.
The attached document explains the reasons and how to modify fixtures to suit it.
CNC Guru
The reason the bore size has been changed from 19mm to 18mm is to ensure cartridges are secure in the Model block while being raced.
The decision was made standardise on the cartridge size and source a “Denford Power Pack” which would cost less than both the older Test and Race cartridges. The size of the hole was reduced at this time to provide a snug fit on the Power Pack for Health and Safety reasons.
This change was made in June 2017.
Understanding that there would be a change over period the F1 competition rules were changed so that both the new and old model blocks are compliant. This would allow customers to use up stock of both cartridges and model blocks.
Check the current racing rules to ensure the Model block you are using is compliant.
The decision was made standardise on the cartridge size and source a “Denford Power Pack” which would cost less than both the older Test and Race cartridges. The size of the hole was reduced at this time to provide a snug fit on the Power Pack for Health and Safety reasons.
This change was made in June 2017.
Understanding that there would be a change over period the F1 competition rules were changed so that both the new and old model blocks are compliant. This would allow customers to use up stock of both cartridges and model blocks.
Check the current racing rules to ensure the Model block you are using is compliant.