Q: I’m getting ready to build a 406 small-block to put into my Camaro.
My question is about the use of block filler. I’ve read that if you fill the block to the bottom of the freeze plug openings, that it will increase the cooling ability because this limits water flow to the oil pan area and increases flow to the head. I’ve also heard that the procedure strengthens the bottom end.
Is this all true? And can it be done to a street engine?
Is there a certain kind of block filler I should use? Are there any other considerations for using block filler? I’d appreciate any help you can offer.
A: The short answer to all of your questions is—yes.
Block filler can improve cooling and cylinder strength, and it can be used in a street engine successfully.
The type of filler you want to use is called “short fill,” which means that enough filler is used to partially fill the water jackets in the block.
A good engine block filler is called HardBlok. You can find the pre-measured short-fill container of HardBlok engine block filler here, which comes with the instructions you’ll need.