GMT 900 Trucks General Discussion 2007 - 2013 Trucks | General Discussion

Anyone done heads on a 4.8/5.3l nnbs?

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Old Mar 24, 2009 | 10:02 PM
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Default Anyone done heads on a 4.8/5.3l nnbs?

I am curious if anyone has done them.I am thinking of going with a tr220 cam,but didnt know if i should get the heads done as well or buy new ones that are already ported with new springs etc..Mine came with 243 casting but arent they detuned some way with smaller valves.I would like to run a stall too.What would you guys reccommend.Thanx peeps.
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Old Mar 29, 2009 | 11:22 AM
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EVERYTHING is the same as far as size specs on valves and everything. the only difference is that the valves arent sodium filled like the old z06 heads and all that was for was to handle higher rpms. your best best is to do a full port/polish/valve and MAYBE mill em down a bit if you're going to keep in n/a.
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Old Mar 29, 2009 | 07:42 PM
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what about l92 (ls9) heads ???
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Old Mar 29, 2009 | 09:21 PM
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The L92 heads need at least a 4.000" bore to keep from smacking the valves into the bore. The 3.780" of the 5.3L will not work. The #243 and #799's are damn good flowing heads stock. The only way to get more power from them is have them ported, polished and larger valves installed.
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Old Mar 30, 2009 | 12:14 AM
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Originally Posted by Ryan02SS
The L92 heads need at least a 4.000" bore to keep from smacking the valves into the bore. The 3.780" of the 5.3L will not work. The #243 and #799's are damn good flowing heads stock. The only way to get more power from them is have them ported, polished and larger valves installed.
how much does it cost to do a P&P on heads
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Old Apr 5, 2009 | 09:55 PM
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how much do i need to have milled off my 243's to get a 4.8 to 11:1 compression? any help would be appreciated
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