Hello,
I have very many problems :-) Here's another one:

I just rebuilt my first 350 SBC. Nothing very wrong, was rebuilt a year ago, but not moved since, so I replaced one headgasket (something had fallen into the cylinder), left the block as it is and swapped the stock manifold and Rochester Quadrashit for Edelbrock Performers, Air cleaner also. everything else is still stock. the engine ran well, idled nicely (but at 34° BTDC, but don't care about that now). Here is my Problem:

When sitting in the garage and idling, it will gladly take the accelerator right up to WOT, without any audible valve train noise or anything. BUT as soon as it's under load (acceleration of the vehicle) it will start rattling at I guess 2500 RPM. It's a rattle as if something was loose. It doesn't lose power, it just rattles, guite loudly though. I don't think its the valves, what else can be lose which only makes a noise once the engine is under load? Does the Carb have any bits that might rattle when vacuum sinks?
THX!