another blown up jetboat motor sbc

[JoePorting]

Doesn't look too lean to me. Maybe the problem is with the springs/retainers/locks. Check to see if they fit right. Make sure you have the right springs with the right pressures. Check pushrod clearance issues. Look to see if there are marks on the pushrods where they may have been rubbing on something.

For the next build I'd dump the import heads and go with a more name brand head.

[MELWAY]

I had a good look at the plugs from the cylinders that were not damaged and there was definitely lean signs.
Since the engine stopped right after running at this point it clearly showed lean. the photo is after I sprayed the oil off with brake clean
Previous plug checks were after a cool down or low speed to the dock,loading the boat, etc. They looked about right. Just a bit of color.

It turns out the street avenger is jetted lean at cruise as the holley guys were expecting a vacuum advance and less load on an automobile setup.

Over at the car sites there is a lot of guys using larger jets on both the primaries and secondaries of the street avengers.
I had never heard of anyone complaining that their holley was not using enough gas.

Feel free to read my plugs. I will have some pictures of the carnage later.

Those plugs look too hot for an endurance engine. And those porcleins. Look like signs of overheating