quisterio

Hello... I'll start off with giving a little background information about my car and parts.... My engine (L98) was taken out and completely rebuilt from the bottom up about 21,000 miles ago, during the rebuild we had some go fast goodies put on it, including a COMP CAMS .500/.510 Lift Camshaft, this cam came with the appropriate springs to handle the extra lift. A little over a year ago I removed the stock stamped steel rocker arms and installed Comp Cams Pro Magnum 1.6 Full Roller Rocker Arms... -------------------------------------------------------------------------------- Today i was driving the car and it was acting better than it ever has, I slow down to make a turn into a gas station and all the sudden my car starts shaking very badly. I turn my car off, get gas, and start it up to drive off, it acts no different. I open the hood with the engine running and notice a really loud "tick tick tick" noise from under my passenger side valve cover.. I figured it was a rocker arm that had come really loose all the sudden, so once I got back I decided to look at it. Once the valve cover was off I wiggled the rocker arms to find the culprit, the intake valve of cylinder #2 had lots of movement in it, as in left, right, and alot of up and down play. I tightened the poly-lock back down to normal and got rid of the play in the rocker arm, i then lightly tightened the rest of the rocker arms that seemed loose while I was under there and then re-assembled everything. When the car fired up things sounded nasty.... I could tell something wasn't right, it sounded like stuff hitting each other, metal on metal... I took it back apart and did a more thorough look... the EXACT same rocker arm that was loose earlier was just as loose as before... i started pulling and tugging on stuff to see what could be loose and making the noises I just heard... The valve spring under the loose rocker arm was completely loose, I could spin it freely, slide it up and down, move it left and right a little bit, and even compress it somewhat with my finger Looking at the spring closer under a light showed me that there's a nice chunk of the spring broken off towards the bottom of it.... ------------------------------------------------------------------------------------- What could have caused my valve spring to suddenly fail? I don't put my motor through any unnecessary stress, it's NEVER revved to red-line, I keep the engine tuned up more than it should be... Now i have to worry about having a burnt valve and the BS amount of money it's gonna take to have this fixed... No matter how hard I try to take car of this car something always goes wrong or breaks... I finally had my car running perfect, I even ordered some new goodies for my motor yesterday... now this happens... I apologize for the long post but I'm a little ticked off and need to let off some steam.. Any info on this would be greatly appreciated...

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mnorton

Coil bind?

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Keepin' it Topless!

1987 20th Anniversary Convertible, Crane 2032, World 305 S/R Torquers w/Crane 99846 Springs, Comp 1.52 Roller Tips, Crane AFPR, K&N's, Airfoil, 22# SVO's, Hooker 2055's, CATCO Cat, DynoMax 3" Catback & Bullet Resonator with Ultra Flo Muffler, Aluminum Driveshaft, Alston SFC's, Spohn LCA's & Panhard, PST Polygraphite Bushings, Bilstein's, Goodyear Eagle F1's, Robbins Rag Top, Ostrich with a Homegrown BIN.

Orr89RocZ

I assume the heads were machined to handle the lift? guide stems cut down?

What springs were you running?

Its possible bad batch of springs and it just happened to fail now. If its an agressive lobe cam you may need to change springs out ever 15K miles or so. Really aggressive setups need fresh springs every 5-7k miles. Its possible 21,000 miles on those springs just started to wear them out.

May want to check some of the other springs with a spring tester to see if they are producing the same pressures they were rated at new. Overtime the spring will weaken and you will not see the same pressures. its possible it weakened enough that it no longer could control the valve and just wore out.

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1989 Twin Turbo IROC-Z
"Twin Turbo 401 Buildup Pics "
"FQuick Garage"
9.86 at 141 mph 14psi, street tune

madmax

Just checking, but I hope you did not do this at whatever position the engine was sitting at when you last shut it off.

Springs sometimes break from flaws, not unheard of, but sometimes there are clearance issues as well and they get into or near coil bind and fail. Running that kind of lift if clearance was not checked this is a possibility.

Damon

A .500 lift cam becomes .533 when you step up to 1.6 rockers. Even assuming you have adequate clearance on everything to handle that, you're working the springs just that much harder with the higher ratio rockers. If I had to guess, I'd say that valve spring's number was just up, given that you have been running that combo for a year.

You didn't burn a valve. If anything happened at all you smacked a piston into the valve, bending it.

Replace the spring, set the lash and do a compression test. If that cylinder is way low (near zero) you bent the valve. If not, you're good to go.

quisterio

I'm afraid I did, it wasn't by much, just barely... I realized that I should not have done this about half a second after i fired it up again...

The only good thing was that it ran for maybe a whole second like that until i shut it off real quick..

I don't know exactly what springs i'm running, just that they came with the camshaft when it was ordered..

Just amazes me how it just went bad all the sudden. and how it didn't act REALLY bad until i tried to fix it by re-adjusting everything...

vetteoz

Brand new Lunati spring rated to .630 lift running @.550. Installed correctly, no coil bind and less than 500 miles



You can see from the end view there was a existing break ( the smooth part ) that was present for some time before spring actually broke.There was a shiny spot inside the break (not visible in pic) where the spring had been working on itself

Orr89RocZ

What comp cam is it? Cam card probably says what springs are in it. Is this a roller cam by the way?