Valve train geometry problem or something else??
Race Director
Joined: May 2005
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From: Millington Illinois
St. Jude Donor '08-'09
Yeah, pretty interesting stuff.
It kind of looks like the spring set up on these heads are heavy for the application. The springs need a diet. They are heavy and hard to control due to their own weight.
It seems like it could be better in this application to have a lighter spring then shim it up to the pressures I need to control the valve and not waste so much of the spring's energy controlling it's own surging.
Also in that article caught the part about shimming a max of .090" then if more is still needed, use spring locators.
It kind of looks like the spring set up on these heads are heavy for the application. The springs need a diet. They are heavy and hard to control due to their own weight.
It seems like it could be better in this application to have a lighter spring then shim it up to the pressures I need to control the valve and not waste so much of the spring's energy controlling it's own surging.
Also in that article caught the part about shimming a max of .090" then if more is still needed, use spring locators.
http://www.summitracing.com/parts/NAL-12499224/
Last edited by 63mako; Nov 2, 2014 at 12:51 PM.
Advanced
Joined: Sep 2014
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From: piney flats tn
Beehives. They are running a lot less seat and open pressure, lighter weight and bump your useable rpm up a lot with minimal harmonics due to the design. Do a search on the LS6 beehives $60, 787-16 Comp retainers $50, stock locks, might need locators. Worked with Pauldana on a set for his old engine and he was pulling 7000+ RPM with no issues. GM is using them with 6500-7000 RPM redlines.
http://www.summitracing.com/parts/NAL-12499224/
http://www.summitracing.com/parts/NAL-12499224/
Another thing to consider when you start tightening up the c/b clearance to anything tighter than ~.050 is that you need to check everything very carefully. You need to put each spring in a vise and measure actual coil bind as it can vary .020-.030" per set, and you have to check installed height on every valve and be able to get them all within +/- a few thou. This also trickles down to the rest of the cyl head to things like valve job depths, spring pocket depths and valve overall lengths.
Thread Starter
Le Mans Master
Joined: Apr 2011
Posts: 6,284
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From: Hermosa
Beehives are reeeeealy critical to being set up right. They don't tolerate too much c/b clearance at all
So it sounds like maybe the set up peculiarities could be a large part of the reason for failure of these springs? Kinda a, "get it right or pay the price" deal.
Another thing to consider when you start tightening up the c/b clearance to anything tighter than ~.050 is that you need to check everything very carefully.
I did measure the coil bind on several of these springs. So far they are all 1.080" give or take a couple thousandths. Makes coil bind even farther away than advertised.
Dart did tell me that they found coil bind at 1.080" as well. At the time I thought it was a good thing.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
Beehives are reeeeealy critical to being set up right. They don't tolerate too much c/b clearance at all and if one breaks, there's nothing to keep the valve from falling into the cyl. and hitting a piston. You're much better off with a single/damper or dual spring.
Another thing to consider when you start tightening up the c/b clearance to anything tighter than ~.050 is that you need to check everything very carefully. You need to put each spring in a vise and measure actual coil bind as it can vary .020-.030" per set, and you have to check installed height on every valve and be able to get them all within +/- a few thou. This also trickles down to the rest of the cyl head to things like valve job depths, spring pocket depths and valve overall lengths.
Another thing to consider when you start tightening up the c/b clearance to anything tighter than ~.050 is that you need to check everything very carefully. You need to put each spring in a vise and measure actual coil bind as it can vary .020-.030" per set, and you have to check installed height on every valve and be able to get them all within +/- a few thou. This also trickles down to the rest of the cyl head to things like valve job depths, spring pocket depths and valve overall lengths.
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Joined: Sep 2014
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From: piney flats tn
They work well if properly set up. GM runs them in everything many with 100,000 mile powertrain warrantees and 6500 RPM redlines. The spring I linked has a max lift of .560. It is used in the Corvette ZO6 LS6, and the 638 HP supercharged LS9 ZR1 and Beehive springs are standard for the past 20 years in all LS engines including the the LSX 454. In a street build with occasional bursts to 6500 it is a proven, economical alternative that works and has been used in every corvette built by GM in the past 20 years. I can see an issue if it breaks. In a dedicated race engine would not be the best option as far as that goes but GM apparently has no problem using them in really severe applications.
Drifting
Joined: Jul 2013
Posts: 1,299
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From: Tri-Cities TN
They work well if properly set up. GM runs them in everything many with 100,000 mile powertrain warrantees and 6500 RPM redlines. The spring I linked has a max lift of .560. It is used in the Corvette ZO6 LS6, and the 638 HP supercharged LS9 ZR1 and Beehive springs are standard for the past 20 years in all LS engines including the the LSX 454. In a street build with occasional bursts to 6500 it is a proven, economical alternative that works and has been used in every corvette built by GM in the past 20 years. I can see an issue if it breaks. In a dedicated race engine would not be the best option as far as that goes but GM apparently has no problem using them in really severe applications.
GM has the millions to frequency test any spring and cam combination. The average guy will not spend $250 an hour for spintron testing. I do not recommend these springs for any aftermarket camshaft unless they want to spintron test the combination.
