Weak 926 springs just ate my intake lobes

[NVRANUF]

Has anyone had problems with comp 926's. 10,000 miles may have been too much with .608/613 lift. Can and lifters are destroyed. 1 good this is I get to go bigger better. Can, heads, link Bar and a Fast intake.

[SMWS6TA]

Depending on your Cam choice take a look at BTR valve springs...

[Firebirdjones]

I'm looking at the spring specs and they aren't all that much of a spring. 109 lbs. seat pressure at 1.8" install height and 317 lbs. at 1.3" compressed.

Seat pressure is pretty light, I run that much or slightly more with flat tappet cams with softer ramp profiles. Problem with light seat pressure and more aggressive roller cams (and some flat tappets) are the valves bouncing off the seats when they close. This is especially a problem with camshafts that have an aggressive closing ramp profile that slams the valves closed. Gotta have spring seat pressure to control that.

Did somebody shim the crap out of them? Are you reusing your stock roller lifters? Miles?? What I have seen are roller needles that get pounded, they stop rolling and that's what wipes out the camshaft.

Trying to determine if you may have had other issues contributing because those aren't killer springs.

[Firebirdjones]

Here's an example of what I run on our LS1

It's a dual spring from Crane much like the Comp Dual spring but as you can see the pressures are much higher.

112 lbs. seat pressure at 1.8" install height, and 352 lbs. at 1.150, and good for .650 lift cams. These springs have been in the car for more than 60,000 miles, original roller lifters, and never a hint of any trouble, no valve float and runs crisp all the way to the 6700 rev limiter. Custom cam has a softer closing ramp profile from Crane.

Generally speaking, a performance small block application with hydraulic roller will want somewhere around 120 lbs. seat pressure, and in the neighborhood of 350 lbs. open pressure. They can tolerate as much as 400-425 lbs. open pressure and still have very respectable valve train life if top quality springs, valve train components, and quality oil is used. Usually at this point is when you need to get into billet rollers that withstand the abuse. Stock rollers made of cast iron wouldn't be happy at those higher spring pressures.

With all that said, it looks to me that it's possible you didn't have enough spring pressure to keep the roller on the lobe, and any slight bouncing it might do, even undetectable, will eventually flatten the rollers and they fail, wiping the cam.
This is just a guess but I see it often. Comp seems to have some of the lightest spring applications with mild seat and mild open pressures when comparing to similar springs from other manufactures. Plus a lot of Comp off the shelf grinds tend to have aggressive ramp profiles on the open and closing side if you aren't careful which series you buy. Not the first time I've heard this issue with Comp.

[SMWS6TA]

FBJ, here are the ones that came with my Cam.

BTR Part #: SK001 Platinum Spring Kit

.660" Lift Dual Spring Kit for LS engines using stock rocker arms. Includes dual polished springs, matching titanium retainers, your choice of locators for stock or bronze guides, locks and seals.



Spring specs are 155 lbs @ 1.780", 380 lbs @ 1.180", 400 lbs @ 1.130, coil bind @ 1.070" This is a drop in spring kit for all 15 degree LS heads including LS1 LS2 LS3 LS4 LS6 L76 L92 L99 LQ4 LQ9 L33 LSA, etc, this kit will also fit LS7 heads with approximately .045" of spring shim, see items SS015 and SS030.

[Firebirdjones]

Those specs look more in line with what I described above for a stout small block performance application with an aggressive lobe profile camshaft that can still have long life with good components used along with good oil.

[NVRANUF]

Springs did get weak flattening 1 roller and chewing up 4 more, all intake. Cam is destroyed.Going with Manley 660 springs and titanium. Will still have an agressive ramp, but now the car will not be driven as often. New cam specs are .613 .623, 227/239.

[Firebirdjones]

Yeah that's what I figured when your post said it was all intake lobes.

Comp Cams grinds a lot of there stuff with a very fast closing ramp on the intake lobes. They do that to get the intake valve closed as soon as possible and shorten the intake event to build more low end cylinder pressure.

The problem with that is the intake valve closing so fast needs a spring with good seat pressure to control it as the valve slams against the seat. Weak seat pressure means that valve flutters against the seat several times after it closes, it beats on the roller lifters and it's also extremely hard on your valve seats and valves

Now for some reason Comp offers a lot of their springs with minimal seat pressure, not sure why, but it eventually causes issues with a camshaft like that with fast closing ramps and you wind up with poor valve control, after a period of time it takes it toll on parts, that's how I came to this sneaky suspicion on your engine when you said intake lobes.

There are some excellent cam grinds out there that are aggressive and make HP yet have softer closing ramps, easier to control the valve train, and less wear and tear on components. Howard was one of the best at it. He did a lot of work for himself as well as Crane and Lunati. The Lunati voodoo cam series is a direct result of everything Howard knew about cam design, and they flat out work. There are also some excellent engine specific shops that have their own proprietary lobe designs they use to make power with a specific engine and have places like Comp grind for them.

[NVRANUF]

Went with a comp core and trutorque level 5 specs. I hope this works out.

[SMWS6TA]

There are also some excellent engine specific shops that have their own proprietary lobe designs they use to make power with a specific engine and have places like Comp grind for them.

mine is from Tick (Martin) and was made by CompCams.

[Firebirdjones]

mine is from Tick (Martin) and was made by CompCams.

Yep, there are a lot of them out there for the LS engine, and they all compete with one another and what they think are their own better lobe designs.

Mine is from Vinci and ground by Crane.

One I see that always makes good power on the dyno is Livernoismotorsports. He has his own lobes and has Comp grind them.

Of course Texas Speed and others.....

[NVRANUF]

The cam I purched was a Geoff Skinner of EPS design. Small 347, 243 bowl blended heads and fast 92.

[SMWS6TA]

I'm taking mine to him for tuning once my transmission is finished rebuilt.

[99'CajunFirehawk157]

The cam I purched was a Geoff Skinner of EPS design. Small 347, 243 bowl blended heads and fast 92.

That cam should be ground by Cammotion by Kipp for Geoff...fwiw. Where in LA do you hangout? Make the Hammond square cruise nights?

[NVRANUF]

Cajun,I hang out in Pumpkin Center, (Adams Road). I've been to quite a few in the mall. Not this or last year because of the camshaft problem. I'll make the next one though. The Pic in my avatar is from the Hammond square mall.

[99'CajunFirehawk157]

Cajun,I hang out in Pumpkin Center, (Adams Road). I've been to quite a few in the mall. Not this or last year because of the camshaft problem. I'll make the next one though. The Pic in my avatar is from the Hammond square mall.

I have some friends that hang out there, one husband and wife that I know owns these 4 rides and are frequently at that cruise in...
Plus a guy with a CETA and another with a super clean third gen firebird (red) I always try to make it but its about a 50 mile trek from my house.

[NVRANUF]

I've met them. That's a really clean gen 3 turbo.

[SeoBets]

Здравствуйте
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