Comp 918 Springs ?
 

I've used the Comp 918's and had 921's on the 402 that was in the car and had No problems with them. Yet I go and grab a new of set of 918's to slap on a 5.3 L33 that I slapped in the 402's place because of Fuel usage. I had the 243's on the L33 massaged by WCCH and I'm sure they had the correct valve height. Letting the 5.3 Idle and not more the 2500 RPM, BOOM started missing and running like crap. Upon removing the R cover, I seen the Comp Carnage on # 8 Intake valve.
Replaced them with PAC 1218's for the small 216/220 .560 lift Cam and it's been good so far. What a pain replacing the spring's with Comp's tool on a 4th gen F Body.

https://cimg1.ibsrv.net/gimg/ls1tech...dfc0f50b02.jpg
They should have made the damn tool just a little taller so U can remove the loose spring without loosening the whole tool to get the spring out !

Might a just been a freak failure but was lucky that the Intake valve did not Kiss the Piston !!
I'm gonna miss the Torque. Maybe I'll Bottle feed the L33 when I need 2 ?

How new were those...??? I have a set of 243's setting on the bench waiting to go on my L33 build, with those Comp 918's on them...wondering about them now...

The Curse of Comp strikes again!!

Damn. I've been running the same set of 918s since 2009. They have a bad rep these days or?

You might be OK. There was a bad batch a while back(not certain when, but I think AFTER yours) that had breakage issues.
Usually when they break, it's not long after installation.

Springs
 

The date on the Springs is Oct 17. I measured about .110 clearance on the intake valve for PTV B4 I sealed up the heads with studs. Must a been good enuff as has 215 psi of Comp on #8 now. i advanced the cam 2 degree's as after I drive it for a while, the chain is gonna stretch .
I've had it running at about 1800 RPM for about 1 hr + and then drove it up to get some juice. Rich as a pig tho have to Tune it now.
Springs might be like the Lottery, 1 chance in ??? 2 get a bad 1. Tho like I may have said, What a PITA changing them while the eng is in the car, specially #'s 6,7 & 8 !

That sucks. I didn't get so lucky when I had a Comp spring break.

I don't use their products. I use Howards or Cranes valve train parts. I understand the PACs are good, but cannot personally recommend them because I have never used them. I know before that Comp had a Brazilian supplier who delivered a batch of bad springs.

The 1218s or 1219s we have are way less $$ and much higher quality plus PAC makes their own springs here in the US. I wont chance a 918 again on an engine and do try to steer customers that way also. There is a reason they come with our 2 signature cams also.

Suprised anyone goes with comp springs with the issues people have had over the years. If not running a dual spring, the pac and psi beehives seem to be a solid choice as i haven't really seen or heard of issues with those.