Head gasket question

[theblindchicken]

Why is the water jacket in the heads so large compared to the holes in the head gasket?

The hole in the gasket is around 1/8" where as the opening in the heads is around 3/4".

I'm assuming this is to limit the flow rate of coolant through the heads to allow the engine to warm up quicker, but this would hinder the coolant flow during high rpms and/or longer trips that may be the cause of the heads overheating and cracking.

I believe if you opened it up all the way, you may not actually be able to warm the engine up due to the coolant passing through at a higher rate.

 

[Honky Kong jr]

Volume and transfer rate if the coolant was allowed to fly right threw it wouldn't absorb heat. You want the volume to absorb heat from the heads and pass threw at a slower rate to absorb as much as possible. Kinda like destructors in a heater core or radiator but for the opposite reason

 

[yevgenievich]

it would overheat if the coolant does not stay long enough to transfer heat. Same reason a stuck open thermostat can actually cause an overheat in a lot of equipment. Similar on industrial air compressors that utilize oil for coolant. They will run hot if thermostat sticks open because the flow of oil will not be regulated any more.