I have heard many accolades for the Edelbrock, and if I was buying new I would also, no doubt have gone down that route. But I got this one off ebay for a song, and it looks like new; very clean and un-messed with. So I decided to persevere for a bit. Also its a 465 CFM which in theory is better matched in size to the 260 engine than a 500CFM.
I got a reply from Gerard on the ‘bob2000.com’ website (that someone here recommended) and he confirmed he thought there was a blockage.
So this morning I took out the right hand idle screw and blew out the carb with compressed air a few times. After I had put back the screw, and set both sides at 2 turns out, I restarted the car. Eureka! Problem solved; I have shifted the blockage, and saved myself a carb strip down.
I think Holleys are good once they have been set up properly, and do run reliably for a long time. But if you have to fix or tune one up, they do have a reputation for being difficult to work with.
But for today, maybe Holleys reputation is restored a little eh?