in bad need of serious solid roller valve springs

[rewguy]

50mm cam core. .904 lifters with the bigger (.813 i believe) wheel. Titanium valves. We've run very similar cams with the same valve lift with smaller cam cores and .842 lifters and the same springs and had no issues. .. that's why we're puzzled.

[sbnova2]

You need to check your numbers for the exhaust again. What you posted I came up with .130 from coil bind not including your lash.

[Strange Magic]

Get yourself a better quality wire, one from PAC or PSI. PAC offers a lot of high frequency duels. Some of the manley next tec stuff reminds me of the K Motion stuff.

[rewguy]

I factored the lash in already. ....1.970-.790=1.180. Cb=1.070. So .110 total.

[BlitzA64]

Would it make sense to lose the +.050 locks on the exhaust side and install standard to give yourself .060 from coil bind as a test?

[wyrmrider]

you could loose the locks but I think a harmonics/ surge problem
can you try some lower ratio rockers on the exhaust?

[monte442]

I already suggested getting rid of the +.050 locks on the exhaust and getting it down to .060 from coil bind. Can you fit a larger diameter pushrod on the exhaust side ?

[ProPower engines]

Had the same issue years ago when we switched from FT to roller. There is a learning curve and where this issue cause me issues was not enough room between coils and they slapped together as the rpm went up.
I used the .050 to .070 from coil bind then increased it to .150 then thinking I was too close to the springs designed coil bind even though the spring spec was measured correctly.

After short run time like the dyno and a spring would break I looked between the coils under a micro scope and found they were barely touching. I went .050 between the coils and the issue was solved.
The real cause was the lobe profile was too violent and after a re-think switched cams and never has an issue.

Just to mention it a Reed Cam I was fighting with at the time ( NASCAR series sponsor ) but I did find a spring that would work but it only worked if I turned the engine tighter where I wanted to be in the 7400 to 7600 range they would break but if it turned 8100 to 8400 they lived longer which meant I did not need to change the springs after qualifying and final practice keeping the laps to under 75 or 80 total because they would only go about 280 to 300 total laps before one would break.

But between 6500 and 7400 on a spin-tron tester down at Isky we discovered the issue with the wave in the coils caused by the violent opening.
You may have opened a kettle of fish that just needs the lid slammed shut at this point you may need to start over

[wyrmrider]

excellent post above- says it all
my feelings exactly about the cam/ spring combination- they have to work together
also add Isky to your short list of spring suppliers
Jones cams are known to be easy on the valvetrain for extended periods (and still make excellent power)
there are tradeoffs
but then he may make the rad ones too-that require more spring or superlightweight valvetrain- you have to get the correct combination
I'm interested in seeing what you come up with

[user-3597028]

Don't use .050” locks. Put one on the valve and you'll see there is almost no support under the keeper groove by the actual keeper itself. The valves like to snap off right there because of this.

I use the 424 Nextek springs at 320/360 on the seat and run them .060” from coil bind. I've never had a problem or seen one break.