Why are the water passages in the head gaskets so small?

[eds1965coupe]

We've noticed that the water passages in the head gaskets, fel pro and others, are only about 1/4" while the triangular passages in the head and the block are much bigger. Is there a reason that the passages in the head gasket shouldn't be enlarged to match the passages in the head and block?

Thanks,

Ed

 

[Eaglo]

Funny, I had the same question. Anyone know why?

 

[rbohm]

8) the small coolant passages are usually close to the cylinder bores, and are steam holes which prevent hot spots. do not open these passages up as there is a reason they are the size they are.

 

[rocklord]

8) the small coolant passages are usually close to the cylinder bores, and are steam holes which prevent hot spots. do not open these passages up as there is a reason they are the size they are.

They're asking why the gasket holes are smaller than the ones in the head and block. Wouldn't the gasket cause a restriction?
Would it help to match the gasket openings to the head/block?

 

[Frankenstang]

Funny, I had the same question. Anyone know why?

That is a good question. This is not the best pics, and it's supposed to be a clevite/engine dynamics gasket off feepay, but IIRC the Felpro I like also has some open some reduced spots in the gasket (note open triangles at 4&6...smaller holes at 1,2,3&5). Rich are you saying these are the intentional steam holes?

 

[rbohm]

8) those holes are right below the plugs which is the hottest part of the engine. on V8's the steam holes are between the cylinders. i think these are for keeping the plugs cool using the small holes to increase the pressure in that area. if you open up the gasket holes, you lose the pressure to cool the plugs. thats all i can think of .

 

[Does10s]

Ya I'm not sure either why some of those holes are small and some larger.

FWIW....On our engine I've modifed both the block deck and the copper head gasket so all of them are small.
Here's an example pic from #6 cyl.

I had the machine shop drill and tap the coolant passage, put in a plug, then drill it for a .100" hole.
The gasket matches this exactly.
Actually the only reason I did this was to increase the distance from the cyl. wall to the coolant passage to help reduce the chance of the cyl. pressure leaking into the cooling system. So far, no leakage.
Later,
Will

 

[MustangSix]

Mostly those are there to eliminate air and steam pockets. They don't need to be larger than the gasket hole. The block passage is large because they have to be able to remove core sand.