I'm putting together my Gen IV 454 block using Fel Pro 1037 Head gaskets. The tips sheet that comes with the gaskets says that the Gen IV blocks need to be drilled to use these gaskets.
See attached pics.
Seems clear but I question it because the old gasket that I removed has all the same water passages as the 1037 and who ever assembled the motor before didn't see the need to drill the block.
Has any one run into this before? Is drilling the block really needed?

Fel-pro offers other choices if you don't feel like drilling the holes. 17040 is the recomended gasket for a mark 4 marine 454. Otherwise I'd drill the holes. Cast iron does drill very easily.

Ive always used the 17040 with success.

I would run a gasket with both water holes open at the rear of the block. One that was designed for a mark 4.

Thanks for the replies. Good advice. I will probably drill the holes. Cheaper than $75 for new gaskets. Since this engine was running OK with this same style of gasket previously without the holes drilled. May have been running hotter than it should on the exhaust side of the heads. Im new to the BBC and wasen't aware of the differences in the different styles of blocks. This forum is great!