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Lq9 408 bored to 427?

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Old 01-28-2010, 04:28 PM
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Default Lq9 408 bored to 427?

I'm going to be pulling my heads off in Mar and starting to gather my parts. My PRC heads will be run through Rich's CNC program at WCCH. So I can't help but think if I pull the 408 and bore it out to 427. With my 4. crank and 4.120 would give me the 427ci.

So the question is can my Lq9 be bored to 4.120?? Or will the walls be too thin? At least its an Iron Block...

Not sure, but I'd rather ask.

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Old 01-28-2010, 04:33 PM
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Most of the blocks I've sonic checked would never go that far. You'd need to have it sleeved or go with a longer stroke to achieve your 427 displacement goal. 4.060" bore with 4.125" stoke will yeild 427 cu in.

Shane
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Old 01-28-2010, 05:17 PM
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You will need a bigger crank for sure. Mine is 4.07" bore and 4.100" crank, but my block is filled up to the water pump ports with Hard Blok. It actually has made my car run cooler with the stock water pump and stock thermostat in every day driving and sitting at idle it gets up to a max of 191, driving it is 174-182. We'll see what it does in the heat of the summer, and what it does if I can ever get back to the track.
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Old 01-28-2010, 05:22 PM
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So what is maxing out an lq block? I was told that you couldn't go much over a 408...
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Old 01-28-2010, 05:42 PM
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I thought this may be the case. I didn't want to swap out the crank but wasn't sure if there was enough meat to bore it out more. Guess I'm stuck with the 408 for now.

I assume the 4.125 crank must be an arm and leg.

Thanks for the answers!
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Old 01-28-2010, 05:46 PM
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Schwank engines is offering a iron 427 stroker and 415ci too...http://www.schwankeshortblocks.com/S...rt%20Block.htm

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Old 01-28-2010, 06:04 PM
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Originally Posted by 1CAMWNDR View Post
You will need a bigger crank for sure. Mine is 4.07" bore and 4.100" crank, but my block is filled up to the water pump ports with Hard Blok. It actually has made my car run cooler with the stock water pump and stock thermostat in every day driving and sitting at idle it gets up to a max of 191, driving it is 174-182. We'll see what it does in the heat of the summer, and what it does if I can ever get back to the track.
Not to go way off topic but is this a common side effect from the hard block? Is it just insulating the cylinder wall, thereby preventing the heat from transfering into the coolant and registering on the gage?
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Old 01-28-2010, 06:35 PM
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More than likely it is because all of the cooling capacity is cooling the top 2" of the cylinder which is where all of the heat is produced. The only real side effect is that the oil may get hotter since the main oil galley that runs down the bottom of the block on the driver's side may have been cooled a bit by the stock configuration. I plan to add a thermostatic oil cooler I have seen the external section to plumb a cooler.
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