Edelbrock made the changes to the performer casting to suit NHRA. They will be straight plug And closed chamber. With the correct valve you can bring them to 69 cc with no problem. They will accommodate all of the combos with ease.
I have an order for 10 pairs,Edelbrock is going to let me know by friday as to when they will start production, i wil let you guys know what they say.
Erik Jones
Jones Engine Development
www.jonesenginedevelopment.com