Originally Posted by
PhilipA
That is not a 3.5 block. It is a cross bolted 4 or 4.6.
If you are just using that photo for illustration it is likely you are pointing to the additional head bolt holes in a 3.5 block.
These were deleted in later blocks.
Sometimes the holes went into the water jackets and sealant was recommended to stop any leaks. I have never seen one that went through to the water jackets but it does happen.
I guess if you have later heads without the extra bolts that you should put plugs in the holes with sealant to stop any leaks.
the reason the extra bolts were deleted is that they tended to "jack" the heads and cause combustion leaks into the valley.
Regards PhilipA
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