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Is there a reason NOT to use 317 heads with correct pistons to achieve 11 to 1 comp

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Is there a reason NOT to use 317 heads with correct pistons to achieve 11 to 1 comp

Old 08-04-2018, 11:07 AM
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Default Is there a reason NOT to use 317 heads with correct pistons to achieve 11 to 1 comp

Every one says 317 heads are junk and maybe I am missing something. With the proper piston cc volume you can obtain any compression deemed necessary for your application.
I want around 11 to 11.4 to 1 compression for a street 370
many companies offer full port and polish for 317 heads.
why shouldn't I do this if I have the heads already ?
this would be with the best flowing intake and headers available
And of course a good cam possibly from BTR.
any opinions appreciated
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Old 08-04-2018, 11:10 AM
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Just speculating, but it might require too much of a dome which could interfere with good flame propagation, and might cause PTV issues as well.
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Old 08-04-2018, 11:13 AM
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Very good points. Thanks
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Old 08-04-2018, 10:08 PM
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I’ve seen quite a few guys get the chambers welded to achieve better compression numbers from the 317 heads. They are basically a 243/799 head with a bigger chamber. I believe that AI (Advanced Induction) offers a CNC port, along with a welded chamber service.
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Old 08-06-2018, 07:52 PM
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I am so torn as to what to do here. Money is an issue so spending the cash to get say 799 heads and have them worked on would be considerably more than working with the 317s I have. I can get around 10.5 to 1 easily with the large chamber 317s with proper piston zero deck and head gasket. The quandary is whether spending the extra cash on different heads is worth the maybe 20 to 30hp that I would gain.
I have a somewhat flexible amount of money to spend but I also have to get the 4l80 worked on plus a convertor and a rearend eventually.
These decisions are killing me!
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Old 08-08-2018, 08:53 AM
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862/706 heads offer roughly 1 point of compression over 317s.

A little hand porting, even with a die grinder and a flapper disc will make them outperform 317s in almost every way. Don't stress too much over the valve size.
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Old 08-08-2018, 11:59 AM
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You could replace the heads a lot cheaper than new pistons. Get the 799 and go you wont regret it, heads are where your focus and money should be spent first and foremost. 799/243 with shelf grind on a 6.0L is a thrilling combo with supporting bolts ons; long tubes, new style truck intake or LS6 400rwhp with ease. Run the stock 6.0 pistons and short block will work fine.
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