I have been trying to get an end cap & have not had any luck through hp reaserch they still have not got any in stock yet. I am a cnc machinest and would like to make my own before next weekend. I was just wondering what size the hole ID should be for best performance & what if any carb mods are to be mad for the end cap.

 

I would say around 2"- 2 1/8" hole. I have seen home made endcaps at 2 1/2". it pretty much just holds the packing in around the sides at that point.

and yes, you will need to re-jet.

 

My hpr cap is exactly 2 1/4' inches inside diameter. The inside is flat from the edge of the can to the edge of the core to hold the packing in. Hope this helps. With my stock carb I had to jet about 170 but Im at 4200 ft. elevation.

 

thank you