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I'd like to get an LS7 for the added cubes, but seem to read about Valve Drop Issues, and having to use Roller Tip Rocker Arms on heads like TSP PRC 285s with Bronze Guides and Titanium Valves.
Is it Best to just go with a 408-418 Stroker with LS3 Heads and Avoid what could be Hassles with LS7???
OR Fork Out the Money for the Pricey Rocker Arms and Extra Cubes Benefit???
I think I'm answering my own question but 2 heads are better than 1, SO ANY RELATED FACTUAL AND BENEFICIAL INFO WOULD BE GREATLY APPRECIATED BEFORE I BUY AN LS7 SOON. THANK YOU.
Last edited by low2001gmc; 05-21-2024 at 02:04 AM.
Are you wanting like an actual LS7? For the money and less headaches I personally push people into 416s with a nice LS3 topend. Only 11ci less yet can still make pretty good power. The OEM LS7 heads will fail sooner or later unfortunately. OEM Ls7 blocks and heads come with a curse.
Are you wanting like an actual LS7? For the money and less headaches I personally push people into 416s with a nice LS3 topend. Only 11ci less yet can still make pretty good power. The OEM LS7 heads will fail sooner or later unfortunately. OEM Ls7 blocks and heads come with a curse.
1st Thank you. Now I'm reading with Aftermarket Heads like TSP PRC 285s which are on LS7 I'm looking at not an issue, just with OEM LS7 heads???
The LS7 block even in stock form can crack the factory sleeves as they are thinnest of all LS blocks. Even with the valve guides sorted as mentioned they can come back again and need redoing. Think of those as more of a maintenance item potentially every 15-20K (or at least check them for play). You could do an LS3 stroker and get custom small bore LS7 heads which a few companies sell.
On a 91 octane 11:1 416 we built running 100% stock L92 heads, LS3 intake/TB and crappy mid length headers into dual 3", alum McLeod Flywheel/RST clutch and T56 Magnum, 335/30/18's it made 560rwhp on a Dynojet with BTR Stage3 cam.
The customer than had the heads ported with upgraded valves, intake manifold rod modded/ported, better long tube headers, and nicer dual 3" exhaust with a custom cam and ported FAST 102mm intake it made very close to 600rwhp on 91 octane. That 40rwhp gain was about $5K in parts. The labor wasn't far off of that as it is a custom AutoX/Road race truck. So if you plan to port the heads.... do that from the beginning!
if you don't already have LS7 stuff in hand, it's not worth going after. Like others mentioned, a 416 with a good LS3 top end will get you close to LS7 performance in a much simpler form. I'd skip the PRC stuff though. GPI has some very nice LS3 packages that incorporate the goodness of the LS7 without the bs.
The bang for the buck is 416 iron block. Strong and affordable. For heads, if you starting from scratch, LS7, but go Brodix, Mast or TFS, depending on budget and a few other specifics. If you already have LS3 heads(I know you do), you can use them, but the intake becomes the restriction and then you are spending more $$$ for a less than ideal setup. Honestly, a good cathedral setup is arguably best bang for the buck pending some things. You got my #, call/text me, can explain more on the phone.
UPDATE: Based on several folks on here valuable information I backed out of purchase and will continue for now with newly rebuilt LS3 with GPI Track Attack Pistons and Rods, ME Ported 823s with 821 Hollow Stems and slightly bigger 1.60 exhaust valves, $299 LSXceleration 238-252, 625-625, 113+4 Cam, ME Ported Fast LSXHR, 4500+ Stalled 4l80 and 4.56s. It's plenty fast in 3700lb Sierra, with A/C, and No Trailer Queen. Just wanted to go bigger like most 🤩.
THANKS TO ALL FOR THE VALUABLE INFO 💪❤️😎. If I can ever be of any assistance to anyone, feel free to holler.
ROB D WATCHMAN ON FACEBOOK AND ADMIN OF SOME LS NATIONAL SITES, 956 802 7700.
Last edited by low2001gmc; 05-21-2024 at 08:35 PM.
Read my thread on LS7 guide wear. Best thing you can do, and you did, is avoid the LS7 heads like a girl with the initials V. D., and I don't mean Veronica Daniels, either!!!
If anyone out there has some LS7 heads that they don't want or need, I would be more than willing to take these paperweights off your hands. Free of charge, of course.
The LS7 block even in stock form can crack the factory sleeves as they are thinnest of all LS blocks. Even with the valve guides sorted as mentioned they can come back again and need redoing. Think of those as more of a maintenance item potentially every 15-20K (or at least check them for play). You could do an LS3 stroker and get custom small bore LS7 heads which a few companies sell.
On a 91 octane 11:1 416 we built running 100% stock L92 heads, LS3 intake/TB and crappy mid length headers into dual 3", alum McLeod Flywheel/RST clutch and T56 Magnum, 335/30/18's it made 560rwhp on a Dynojet with BTR Stage3 cam.
The customer than had the heads ported with upgraded valves, intake manifold rod modded/ported, better long tube headers, and nicer dual 3" exhaust with a custom cam and ported FAST 102mm intake it made very close to 600rwhp on 91 octane. That 40rwhp gain was about $5K in parts. The labor wasn't far off of that as it is a custom AutoX/Road race truck. So if you plan to port the heads.... do that from the beginning!
The LS7 sleeve cracking isn't solely due to them being too thin. It is caused mainly from detonation AND/or from the sleeves being cast from very hard material. BUT-I do agree with building the 416. I have had an LS7 now for 10 years. Considering what I've been thru, if I knew then what I know now, I'd either sleeve a 5.3 aluminum block to a 4.125 bore, or go with the 416. See Tony M for which heads to run on whatever you choose. My .02....
05-21-2024, 01:47 AM
LS7 PROS & CONS, Dropped Valves, Roller Rockers, PLEASE 
