Newest ideas for coolant holes in aftermarket blocks
 

So what is the newest thoughts for what coolant holes and where on aftermarket blocks not dry deck running? Just copy factory size and locations?

some of the original are way close when you go to bigger bore

Cometic has a MLS gasket available with small water holes.


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I think the butlers make a larger bore gasket . Believe it locates the holes away from the bore some.

When we did my IA2 block for my street 505 engine Pontiac Dude furnished us with details where he drilled his blocks that used revised smaller cooling holes. Among other considerations, as suggested above away from the bore some.
Based on it we had Cometic make a custom gasket for us. It has specific part number assigned to the design by Cometic with a 4.380" bore / .040" thick.

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A fwiw, regarding the special gaskets I mentioned in post #3 above I was told they have 20 percent smaller cooling holes in certain locations.


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Steve I think I got the same from Dude.

Bore is going to probably be 4.350, but way smaller as delivered on the aluminum IA. Not sure if they are thicker around than the iron blocks since they have the sleeve and the aluminum support or it. or any siamesing in there, like where the "421" hole is.

Cometics can make them with custom sized holes. Butler's holes are "proprietary" and they will not sell his gasket pattern to someone else.

Just drilled my 48s for coolant between the center exhausts. Block has been done awhile ago.