It sounded like at first a cam lobe issue or valve adjustment. once I read further and you stated empi carbs I was going to tell you to scrap them. I see several customers arrive with empi weber copies and they are junk. We have gotten to the point we will tune them but can't guarantee how they will run tomorrow.
I know you narrowed it down to the EMPI carbs, but i am just curious - did you keep the electronic points in the new distributor?
I had intermittent issues with the new pertronix in my bus. swapped them out for points in the SVDA and works awesome.
Carlisle weekend it ran flawlessly for 152 miles even with the Empi carbs dialed in. Switched to real Weber 34' s and switched out the dizzy today to a new one with points. For the heck of it , I 'll do new plugs in the am. I will know next tuesday what the issue us....the noise that is no longer there concerns me. Who ever ends up with this speedster will certainly have one that is very well sorted and then some as I'll put another 100 miles on it before I put it up for sale.
