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I'm replacing 823 heads that were rebuilt and had .004 cut. Reason in photo's below. Trying to keep around or under 3k/pair for the spend.
Looking at:
NEW stock LS3, but will run dual .660 springs
Texas Speed Brawler
PRC (same as TSP??)
Trick Flow Gen X
Dart SHP
This is going in a daily driven AWD Sierra 6.2L. Cam is GPI LLVVT2, lift maxes out at .553, BTR LS3 shaft rocker system, BTR 3/8 7.5" pushrods and Johnson 2126 link bars. Also throwing 14 psi with a D1SC at it, because I haven't already broken enough crap without getting into boost. Absolutely LOVED the low end (idle to 2500) of the truck and want to retain or improve it if possible. Never got it into boost since I was still breaking in the motor when a valve spring broke, yeeted a valve and ruined the soiree.
Sooo....
1. Am I overlooking an option I should give a hard look at?
2. Can I use the BTR LS3 shaft/OEM rockers with the heads that run an 11, 12, etc degree valve angle without causing problems?
3. Safe to assume aftermarket guides won't last as long as the powdered metal OEM guides?
4. The 823s were 260cc intake- wouldn't going bigger make it lazier down low due to decreased velocity?
Leaning mostly towards the LS3 replacements because OEM, closest to 823/expectations, slight static CR bump, and budget.
TFS 255 LS3 heads would beat the stock LS3 heads from idle to redline. I don't know if I would pay the extra money for those over a used set of 823 heads though.
I also doubt aftermarket guides are going to last as long as OEM powdered steel guides either.
Don't think the BTR rockers for 15° heads will work on 12° heads. Have you considered a set of Brodix BR3 cylinder heads?
CNC-Motorsports has a set of BR3 bare cylinder heads for $1840. Outfit them with a good set of Ferrea valves and a quality spring kit with titanium retainers from BTR and call it done.
Last edited by 01CamaroSSTx; Aug 13, 2025 at 09:45 PM.
TFS 255 LS3 heads would beat the stock LS3 heads from idle to redline. I don't know if I would pay the extra money for those over a used set of 823 heads though.
I also doubt aftermarket guides are going to last as long as OEM powdered steel guides either.
That's the challenge- finding a good used set of 823's. I think GPI has some for their porting program, but seems like fleabay has a bunch of knock off or 364s listed as 823.
As much as I'd like to go for max flow, longevity is crucial. Same reason I went with 4032 pistons- I don't want to tear down every 50 or 100k even.
Don't think the BTR rockers for 15° heads will work on 12° heads. Have you considered a set of Brodix BR3 cylinder heads?
CNC-Motorsports has a set of BR3 bare cylinder heads for $1840. Outfit them with a good set of Ferrea valves and a quality spring kit with titanium retainers from BTR and call it done.
I'll have to look into doing that. My machine shop is a little over an hour away, so building a set is more challenging than it should be...
Want anything that is not 15° not play nice with the factory rocker setup?
those, the tfs 13.5*, and all the other altered valve angles heads run the stock geometry rocker setup.
the base where the rocker mounts will be moved the same amount to keep the geometry same same, just the angle changes.
(Exception will be the truly high end and exotic stuff, but those are almost always explained up front you need these p/n rockers to work)
obviously ls1 needs to stay ls1 type rockers, ls3, ls7 etc…
meow, you do need to look at roller rockers for bronze guides if you want them to last. Pm guides will survive the side loading the oem rocker pads will impart to the valve stem.
I have seen a lot of 823 heads w/ cracks between the valve seats. They don't leak, but it's an invite to dropping a seat and then everything goes boom. My machinist has seen 2 sets of TFS 255's crack along the lower bolt holes. For longevity, the PM guides are the best, but you can have those put in as special order in some cases. Might call around some and get more info. The Brodix BR3 are excellent, I might be able to get you a deal on a new set from them, but they do have bronze guides.
I have seen a lot of 823 heads w/ cracks between the valve seats. They don't leak, but it's an invite to dropping a seat and then everything goes boom. My machinist has seen 2 sets of TFS 255's crack along the lower bolt holes. For longevity, the PM guides are the best, but you can have those put in as special order in some cases. Might call around some and get more info. The Brodix BR3 are excellent, I might be able to get you a deal on a new set from them, but they do have bronze guides.
I appreciate the intel and offer! I think the brodix may be a little too far outside of my reach.
At this point, taking availability /speed of shipment, longevity and budget into consideration I'm debating if the GPI CNC l92 heads are going to be worth the extra cost over throwing new PAC or BTR dual springs into some brand new 821 heads and calling it a day.
Also, mad props to summit for checking into buying a single TBC piston for me. Can't be done and I'm not dropping 1100+ for a single piston from a set of 8. Plan B is buy the same uncoated piston and have it done locally, unless anyone knows who Mahle uses for thermal coating (swaintech?) to make sure all my pistons are in the same TBC gang.
Is that a stock bore L92? Do you have the piston part number? I certainly don’t have the connections that Summit has by any means, but I know a lot of shops with lots of inventory.
Is that a stock bore L92? Do you have the piston part number? I certainly don’t have the connections that Summit has by any means, but I know a lot of shops with lots of inventory.
.05 over L9H- 4.070
930227870T is the part number for the pistons I have.
930227870-1 is supposed to be the same SINGLE piston without TBC. $90 plus cost of coating so maybe 150 all in?
No luck for my contacts. Looks like you can def buy the single though. It will ship direct from Mahle. Mahle offers a TBC also. Maybe call them direct?
Heads from NASCAR racing engines can be "had for a song" after their time is UP.
The LS-3 Head is a Hendricks CUP head.
The BEST, like new, choice, call Rick.
Lance
Heads from NASCAR racing engines can be "had for a song" after their time is UP.
The LS-3 Head is a Hendricks CUP head.
The BEST, like new, choice, call Rick.
Lance
Lance, Hendricks lead guy Randy Dorton…RIP…was heavily involved with the design as well as Warren Johnson from NHRA glory days. That head however never made it to CUP useage. Instead NASCAR mandated that all manufacturers could use a clean sheet design that involved a 4.5” bore center. This was mostly due to Toyota coming along and not having a V8 ready to go CUP racing. The R07 was GM’s bullet that was brought to the table in that endeavor, and it’s still in use today, although it’s been reiterated a couple times for advancements in power. The GM part number for the CUP head is #17802715. It’s a canted valve, spread bore, full on race head. But you’re correct about the pricing…you can pick a pair up for under $3k with rockers. Rockers sit on Ti stands. Very nice stuff. The almost impossible part is finding an R07 block to build upon. That block is a CG material and goes for $10kish if you can find one.
I bought an engine from Keith Dorton in Concord many years ago for my circle track stuff and learned a lot about the development of the L92 head from him.
I appreciate the intel and offer! I think the brodix may be a little too far outside of my reach.
At this point, taking availability /speed of shipment, longevity and budget into consideration I'm debating if the GPI CNC l92 heads are going to be worth the extra cost over throwing new PAC or BTR dual springs into some brand new 821 heads and calling it a day.
Also, mad props to summit for checking into buying a single TBC piston for me. Can't be done and I'm not dropping 1100+ for a single piston from a set of 8. Plan B is buy the same uncoated piston and have it done locally, unless anyone knows who Mahle uses for thermal coating (swaintech?) to make sure all my pistons are in the same TBC gang.
GPI stuff is awesome and their customer service is A+++. I would lean towards that, I think it's a good value. Def do new hollowstem GM intake valves, also. As far as the piston, like everyone else said, call Mahle direct and see what they say.
No luck for my contacts. Looks like you can def buy the single though. It will ship direct from Mahle. Mahle offers a TBC also. Maybe call them direct?
Appreciate you trying! I will- hoping I get a better answer than summit- I'll offer to show some leg 😂
GPI stuff is awesome and their customer service is A+++. I would lean towards that, I think it's a good value. Def do new hollowstem GM intake valves, also. As far as the piston, like everyone else said, call Mahle direct and see what they say.
Roger! I have their cam that is 2* llonger duration than the previous comp cam, and I fully expected to lose low end. It pulls soo much better than the comp- and the idle is insanely ratty.
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Head Choices? 
