I fired the 454 up Friday and it fired right up and ran but it is popping out the exhaust. Does this sound like timing or carb, or what? I could have a valve too tight, but I was very carefull to adjust them one cylinder at a time, so I don't think it is that. Any thoughts?

is the firing order right? and what are you running for valve train? solid or hyd.. roller rockers or stock

I'll agree with checking the firing order, also check for an ignition miss.

Is it a slight pop? could be that your idle mixture screws are set to lean. Does it pop when you give it a little gas?

I'm running an XE-268 ( I think) Comp Cams with Comp Cams roller rockers and matching springs. It pops at steady throttle under 3000 RPM. It does pop some when I give it gas but not always. I'm going to adjust the valves and get the timing light on it and see what I can come up with.

When I put the roller rockers on my small block the instructions called for one full but that was way two much I ended up going 1/2 turn to get it to run right