Mismatched head and block - which gasket

[rick240zed]

Please don't tell me to search - as you will see, I have. And the answers vary and contradict.

 

I would like people to provide explanations for the answer, and not just a vote.

 

 

Here are some, match the head posts:

 

http://forums.hybridz.org/topic/93164-preparing-78-280z-for-turbo-swap-reusing-stock-block/?p=878887

 

http://forums.hybridz.org/topic/68264-which-head-gasket-l24-p90-turbo/?p=642230

 

http://forums.hybridz.org/topic/68264-which-head-gasket-l24-p90-turbo/?p=642327

 

http://forums.hybridz.org/topic/68917-p90-head-on-a-77-block/?p=1105677

 

Here are some match the block posts:

 

http://forums.hybridz.org/topic/92946-putting-p90head-on-a-75-280z-block/?p=877438

 

http://forums.hybridz.org/topic/70335-n47-head-on-a-flat-top-l28/?p=665985

 

http://forums.hybridz.org/topic/66997-felpro-head-gasket-question/?p=669237

 

http://forums.hybridz.org/topic/47953-wrong-headgasket/?p=413493

 

http://forums.hybridz.org/topic/105907-p90-head-on-n42-block-na/?p=990794

 

http://forums.hybridz.org/topic/102185-shaving-p90-head/?p=956811

 

http://forums.hybridz.org/topic/66997-felpro-head-gasket-question/?p=629556

 

Here are some that talk about gaskets with extra holes:

 

http://forums.hybridz.org/topic/101675-head-gasket-confusion/?p=952624

 

http://forums.hybridz.org/topic/98875-90mm-gasket-coolant-holes/?p=929474

 

And here's one from TonyD saying to machine block and head to whatever gasket you have:

 

http://forums.hybridz.org/topic/101675-head-gasket-confusion/?p=953209

 

 

So what is the real answer, and why? Please, if you don't know why, don't post and wait for someone to come with an explanation.

 

Also, is it less relevant on a lower power street car (my application)?

 

[NewZed]

Coolant flows from the block to the head.  The gasket would be designed to control and balance flow in to the head, I would think.  So if all of the holes in to the head are open, you're good, the gasket can do its job.  Seems like the gasket that matches the head would be the way to go.  If there are holes in to the head that don't have a matching hole from the block then that's where working on the block to give the head what it needs might matter. I haven't seen where anyone's done that but maybe it happens.

[rick240zed]

Sounds reasonable, but...

 

I've decided to completely avoid the issue, and will be using an F54 block to go along with the P90 head.

[steve260z]

http://forums.hybrid...holes/?p=929474

 

That's my thread. I've been running the metal head gasket that did not match perfectly (N54/P90) but I've had no (known) issues...FWIW