It's a 305 ci chevy engine. It has a loud tick, can't say it's a knock as it doesn't sound like a bearing, and watching the rocker arms as it runs, the tick goes to the beat of the rocker arm (or valve), not to the beat of the rod. Also, some of the time, the noise stops completely and sometimes is only intermittent. I thought that maybe someone dropped a small bolt into the carb that got into the cylinder. I did notice that one of the rocker arms isn't moving like the others, maybe a bad lifter and hopefully not a bad cam lobe, but/and I can't say that the noise is coming from that cylinder area, and this noise doesn't sound like a lifter either. WTF??? Any ideas?????? I am going to pull the intake this week. Any ideas from some of the experienced motor heads would be appreciated. I've been around engines in great detail for some years myself, but this isn't a regular sound that I can make a "for sure" call on. Thanks in advance for any ideas you guys may have.