L92 stock valves NOT GOOD
02-29-2008, 11:37 PM
#21
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FWIW I weighed up some valves a while back:
Stock L92 intake-108.6 grams -- Some non magnetic alloy
Manley 11620 -119 grams- Intake- The Manleys are solid SS
Manley 11621-92 grams- Exh
LS3 intake -89 grams -- hollow alloy and my current favorite (NA) with single springs
LS3 exh same part# as L92 Exh- some non magnetic alloy
Stock L92 intake-108.6 grams -- Some non magnetic alloy
Manley 11620 -119 grams- Intake- The Manleys are solid SS
Manley 11621-92 grams- Exh
LS3 intake -89 grams -- hollow alloy and my current favorite (NA) with single springs
LS3 exh same part# as L92 Exh- some non magnetic alloy
You didn't list the weight of the L92/LS3 exhaust valve, got a number to compare to the Manley exhaust grams?
03-01-2008, 06:38 AM
#22
Yeah, those Manleys are fricking heavy compared to the LS3 hollow valves I replaced. But those big valves don't have to move much compared to the exhaust. The Comp 921 springs should help some.
You didn't list the weight of the L92/LS3 exhaust valve, got a number to compare to the Manley exhaust grams?
You didn't list the weight of the L92/LS3 exhaust valve, got a number to compare to the Manley exhaust grams?
The Manley intakes are the "right" boosted valve.
03-01-2008, 06:43 AM
#23
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Hmmh, seems the stock 6.0 valves do the same thing. Had a 70yr old customer driving her truck and dropped a valve. Owned it since new and didn't abuse it. This was a 2003 hd 2500.
03-01-2008, 08:20 AM
#24
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I work at a GM service dept and we have not seen any valve failures on the 6.2L as of yet. I did call one my friends at TAC in Detroit and he said the valve problem is no worse than the few we see in the Gen III engines. Just a theory, maybe the factory springs pressure is not enough to pull these big valves back closed quickly enough and maybe not enough seat pressure to keep the intake valves seated? Higher rpms would be even more dramatic. So we then have a possible valve to piston contact issue? And maybe my theory just makes me feel better about my setup also?? Ha Ha Ha
03-01-2008, 08:54 AM
#25
I work at a GM service dept and we have not seen any valve failures on the 6.2L as of yet. I did call one my friends at TAC in Detroit and he said the valve problem is no worse than the few we see in the Gen III engines. Just a theory, maybe the factory springs pressure is not enough to pull these big valves back closed quickly enough and maybe not enough seat pressure to keep the intake valves seated? Higher rpms would be even more dramatic. So we then have a possible valve to piston contact issue? And maybe my theory just makes me feel better about my setup also?? Ha Ha Ha
03-01-2008, 11:20 AM
#27
I have another new set of the Manley SSs intakes if those can make you feel better?
blu00rdstr above is going to try and blow his up as well
blu00rdstr above is going to try and blow his up as well
So how much are these and are they a direct replacement or modification, etc?
03-01-2008, 11:36 AM
#29
****, I have an order in for a full set of stockers from GMPD that are on the way. Would return them however the web site states that this is a special order item and non-returnable. Now what?? Nothing like buying two sets of valves for your heads.
Will be running #26918 springs
Will be running #26918 springs
I'm thinking it's better than buying 2 engines for your car.
03-01-2008, 11:50 AM
#30
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ding ding ding... you got it. the posts above are classic signs of too weak of a valve spring for the valve. engineers seem to love these "barely enough pressure" springs. The problem arises when you get a weaker batch of springs than the minimums they accounted for, or after 60 or 70k the heat cycling weakens them just enough to let the valve beat the **** out of everything.
03-01-2008, 05:48 PM
#31
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info from the gm technicians dealer forum- seems some of the 6.2 L92 engines are having problems with the valves breaking off,, some have posted the valve broke right where the keepers go and another stated that is broke off behind the head of the valve,, taking out pistons, cylinders, engines locked right up.
and these are just stock trucks, several have already posted that they have trucks at there dealers waiting for an engine.
i guess those of us with stock valve L92's are screwed, if the valves are having issues on stock truck engines, what will they do at 7000 rpm with high spring pressure
.
and these are just stock trucks, several have already posted that they have trucks at there dealers waiting for an engine.
i guess those of us with stock valve L92's are screwed, if the valves are having issues on stock truck engines, what will they do at 7000 rpm with high spring pressure
.
03-04-2008, 08:58 AM
#33
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L92 valves ****, I have an order in for a full set of stockers from GMPD that are on the way. Would return them however the web site states that this is a special order item and non-returnable. Now what?? Nothing like buying two sets of valves for your heads.
Will be running #26918 springs
Will be running #26918 springs
If you havent already bought your springs, you might want to do a search over on LS1GTO and check out some of the broken 918's there. If you are running a big cam trouble could be looking for you.
03-04-2008, 10:18 AM
#39
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after some investigating... I find it interesting and amusing that this Yeahdoug guy shows up any time there is a shitstorm about valve spring problems. 
I wonder what company he works for 
I wonder what company he works for
03-04-2008, 10:24 AM
#40
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I'll just let all the mis-information about springs continue to spread. Doesn't matter to me. You obviously know more about them than me. When one of my Pro-stock customers calls me today, I'll forward it on to you.
Sorry for the Hijack.
Like others have said. Part of the problem is not having enough spring to control that heavy *** valve. If you want to run beehives try installing them a little tighter for some extra seat pressure (keeping enough clearance to coil bind) or just run duals (patriots, 921, etc)
Last edited by Yeahdoug; 03-04-2008 at 10:34 AM.