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LS2 Heads... What are these holes and do I need to plug them?

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Old Nov 17, 2012 | 10:28 PM
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Default LS2 Heads... What are these holes and do I need to plug them?

I'm currently reassembling my car after some new lifters and head refurbing. I'm having trouble remembering if I had all of the plugs for these holes or not. I have the hardware for all four holes, but only the metal pieces for two. I don't remember if I had them before disassembling or if the guy before me neglected to put them back. What do they do and are they essential? Thanks







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Old Nov 17, 2012 | 10:37 PM
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You should have a coolant crossover pipe for the front. It goes to the radiator
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Old Nov 17, 2012 | 10:52 PM
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Originally Posted by babbage1109
You should have a coolant crossover pipe for the front. It goes to the radiator
Thanks! I was going nuts trying to figure it out. You're the man!!
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Old Nov 17, 2012 | 10:53 PM
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Np. I just pulled my heads lol its fresh in my mind
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Old Nov 18, 2012 | 09:00 AM
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Yeah, those are Steam vents.

You can block the rear ports and run the crossover in the front. Block offs should be on the back. The heads are identical, so they're not on wrong, just move the "plugs."
Or find a way to plumb the rears so where they are functional, is actually the better idea. There's a couple kits out there.

Last edited by bayer-z28; Nov 18, 2012 at 09:09 AM.
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Old Nov 18, 2012 | 03:31 PM
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Originally Posted by bayer-z28
Yeah, those are Steam vents.

You can block the rear ports and run the crossover in the front. Block offs should be on the back. The heads are identical, so they're not on wrong, just move the "plugs."
Or find a way to plumb the rears so where they are functional, is actually the better idea. There's a couple kits out there.
Does plumbing the rears have any benefits?
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Old Nov 18, 2012 | 05:43 PM
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^ Proper coolant system function. GM plugged the back vents for a couple years, but they started to run them again. There's something to do with pockets of air and creating hot spots that running the rear vents alleviates.

It's not an absolute MUST, but if you want to be picky..... I've been running block offs for years, but would like to make them functional again.
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Old Nov 18, 2012 | 06:08 PM
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Originally Posted by bayer-z28
^ Proper coolant system function. GM plugged the back vents for a couple years, but they started to run them again. There's something to do with pockets of air and creating hot spots that running the rear vents alleviates.

It's not an absolute MUST, but if you want to be picky..... I've been running block offs for years, but would like to make them functional again.
Hmm, sounds like something I should put on the list. Have a few other musts before it though!! lol
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