Head gasket question
 

So which head gasket do I need to use on my stock 40 engine ?The one that match the block or the ones that match the head ?

Re: Head gasket question
 

I'd use the one with round holes.

Re: Head gasket question
 

Thanks Jack. I was gonna reach out to you about this.

Re: Head gasket question
 

Re: Head gasket question
 

I'd use the lower one myself. Larger holes allow more water flow. I know, more flow less flow debate has been going on for eons. That debate probably was started by the engine designers before designs went into production.

Re: Head gasket question
 

I don't know much about this, as I am strictly an "8BA Guy", but isn't there a rule saying you should use the gasket that matches the block?

Re: Head gasket question
 

My understanding is:
The trapezoid centre holes were initial gaskets in use. Then to better control water flow circulating through the block the gaskets with the round centre holes were introduced.
All in the way to keep better overall block temperature.
I am using the ones with round centre holes in a 59a engine, recent rebuild.
Phil NZ

Re: Head gasket question
 

Just a thought. The water travels through the block and heads at the openings made, the gasket, unless the holes in the gasket are smaller to restrict flow, won't do much. So it makes since. Distribute or constrict the water flow. Always put the small hole to the front of the block, like on a yblock. If not it'll have no effect. Moving water to the back of the block is a good thing. On a 59a that would force water to the rest of the block. I don't know for certain it's better. I'll leave that up to everyone else.


Not sure but I'd guess the heads don't have trapezoids. Or at least I have not seen it. Doesn't mean it doesn't exist obliviously. It would not surprise me that I know everything. That's a joke by the way.

Re: Head gasket question
 

Either one will work fine . . . though I tend to only use the ones with round holes.

From everything I know (which is not much - LOL), Ford decided to restrict the amount of water flow that too easily headed up to the center water outlets on the 39-42 engines . . . supposedly forcing more water to the other areas of the block - especially the rear. One example is the 39 - 42 Merc blocks - where they changed the center trapezoid water hole for a smaller round one.

They continued this quest when they made the 49-53 blocks - where they had much bigger water outlet holes in the rear of the block than in the front. As some have noted, almost all engines run hotter in the rear cylinders that the front cylinders . . . location, location, location . . .