Verdict on HS2 Modifications

Worthwhile! Cost was almost nill (could have been if I modified the needles myself)If you plan on running HS2's with any type of head that flows better that standard strongly consider these simple mods. Loads of difference above 4500rpm. Pickup is FAR better as the pistons aren't restricting the flow as badly now and on the top end they aren't hanging around in the threw flow. The 1.8oz springs are working nicely, no flutter or hesitation at low rpm and those piston dampers are useless. That racer who complained about flutter without the dampers is crazy. The only way I can get flutter is to remove the springs completely, pistons start jumping up and down like crazy at idle then. Video to come

Summary: 

Started with lean BO needles in standard carbs with dampers on the standard mk3 cam.

• Removed dampers - somewhat better 
• Modified Spring to 2.5 oz - top end went lean
• Fitted ABT needles - mixture went a touch rich on the top end, noticeable, positive change, hesitation at 3500rpm
• Modified Spring to 1.8oz - mixture perfect, noticeable quicker
• Modified Spring to 1oz - mixture went lean and hesitated at 2000rpm (Could be solved by a richer needle I think)
• Pistons and Dashpots shaved .100" - Improvement at 4700rpm to red line (now 7K)

On another note; I am going to have to return to an early slave cylinder however as the pedal has far to much through to work the clutch now. It's be perfect for daily driving but for quick shifts I hate having to drive the pedal all the way to the floor now. Will have to order a rebuild kit for the other.

First video is a takeoff, second is just cruising to show the engine runs perfectly fine and normal under normal driving circumstances.