I have a pair of gen 4 502 blocks and twice now I have dropped valve seats out from number 7 cylinder and also tuliped vales and burned a hole in the valve on the starbord motor. this same thing has happened on two totally different motors on the same side. that same cylinder on the starbord motor the spark plug regularly comes loose. both motors have had the same dart intake, proline carb, thunderboth ignition, and combination mecanical fuel pump backed up with an electronic fuel pump. Just prior to this most recent motor mishap I replaced the thunderbolt ignition module and also scrapped the combo fuel pumps and installed one good mecanical pump.

Is this a common problem with valve seat on this gen 4 motor?

Is this a common problem caused by the gen 4 block?

Is this a thunderbolt problem?

Fuel issue?

intake issue?

Thanks in advance
Pat

Sounds like a detonation issue to lean, to much timing or bad fuel. I would check fuel flow and pressure first.

what brian said,,what cfm carbs you running?? stock heads??
circulation pump?? give all the statistics on the engines..
are you running good inconel valves??

Carbs are 850s stock heads circulation pump with cross over. Im sorry I can't answer about the valves, I have no idea.