I have a 454 GM motor in my boat. block casting number 10237297 which comes up as a vortech motor. I assume that the heads would be Vortech heads, which then would take a longer spark plug. I have been running the Delco MR 43 TS, . But seem to be running really cool at idle. Just wanted to make sure i put in the right plugs, so not to damage the pistons. Serial number of the motor 12568777. Thanks. Dan

They are a pretty good plug and should be fine for a BBC. I run Autolite APP25 I all my big blocks and they don't do that. If you want one up on that, just go to a XP25

Thanks, I was thinking of putting in Delco MR 43LTS. But wanted to make sure not to hit the piston.

if thats the base oval port engine it does take the longer plugs

Thanks, i do know it has rectangular port heads