well i changed my valve springs over to some comp 982s, did that little home lap job. Car runs great.

Its better than ever at part throttle, letting out the clutch has improved 1000 percent, before it would spit and sputter and i had to give it alot of gast to get going.

Everything is good till WOT around 5000 rpm or so to 5500, this violent gurgle and accompanying vibration starts and power basically vanishes. Its bad enough that I let off immediately.
AFR is good, wideband is showing mid 12s

plugs are all firing, got new wires, cap , rotor

basically all i did was valvesprings and now it sounds like the engine is going to self destruct at 5500 rpm and i shift usually at 6. The car runs great at every other rpm


BTW i pulled #3 plug and it looked good but i thought maybe it was showing a hint of knock so i backed the timing way off to 31 total instead of the usual 35 and it didnt change a thing

 

btw i put one full turn past 0 lash with the engine running.. thats how ive always done it

 

btw before I did this the car ran fine even with a bunch of broken valvespring dampers at high rpm

 

Depending on the agressiveness of the cam ramps, you may need to back'em off a bit. Assuming they are all at 1-turn, back off a 1/4 at a time...you shuold be able to go all the way back to 1/4 turn past zero lash without ill-effects.

Just don't go pulling the head just yet

How the fluck are ya anyways? Still in the military?

 

I would try setting lash at 1/2 turn, but sounds like valve float. What are the clearances on these springs (coil bind, retainer interference, etc.)? Something is dead wrong if power falls off a cliff like it sounds.

 

i've experienced the same thing with chevy's "old" reccomended valve preload setting!try 1/4 turn before you go blaming other stuff.if that's not it,check those springs for seat/open pressure and coil bind.
hope it's the former and not the latter!15 minutes beats poppin' springs!
good luck!and keep us posted!
Eric

 

well i ruled out my msd and coil so i guess it may be the lash,

Man I hope you guys are right, it just seems far fetched though that ive always set it at 1 turn with several different springs, I get some comp 982s and whammo 1 turn is too much all of the sudden to cause sudden and massive valve float?

This thing sounds terrible when it hits 5500, Im gonna try setting em at 1/4 turn and hope you are right.

The installed height I must say is higher than it should be the head has had a valve job or two and I didnt shim the springs but really it was never a problem with the even crappier springs before and I dont think it would be such a big deal. These springs are rated to .5 lift and im at .497 or so and with the added installed height i have more than enough room before bind.

These springs are alot stiffer than the ones I used before. You suppose that could be affecting the lifters in a manner to cause this coupled with too much lash or something?


btw Yo mike, hows it goin? Im still in, coming up on 4 years in may. I have a 5 year contract and Im probably gonna re-enlist, Im shooting for air crew, hopefully first navigator on c130s but I may take a helo crew chief position if they sweeten the deal up. I need some more action, being a mech is boring.

 

ok reset lash to 1/4 turn, didnt fix the problem, i guess im gonna try changing the plugs next

 

If that doesn't fix it, I would try a new set of the old crappy springs. It sounds like some kind of interference with the spring or possibly coil bind.

 

Anyone have any other ideas?

Im going to change the plugs but I highly doubt its the cause of the problem. Ive allready changed the plug wires.

I dont see how the new springs could be causing it but being that its the only thing I changed I cant rule them out. I would think if it were going to be valve float it would have been apparent with the crappy springs more so than with these, and coil bind, wouldnt that just bend pushrods and break springs?

 

well i swapped out plugs, no change at all, the problem is still there


I would like to know how a brand new set of high quality springs would be the cause of this. I ran stock springs from napa that would break every 5000 miles and the car hauled *** when they werent broken.

The only thing i havent changed or tested ignition wise is pickup coil, rotor, and ignition module

I figured it was something i messed with when i was changing the springs on the ignition side and i didnt mess with the stuff i havent changed. 5500 rpm and i hear what sounds like destruction despite the car running strong as all heck to 5000, the midrange seems strong or stronger than ever.

 

Why do you keep breaking springs? That will be the answer to your problem. A newbie I would give a straight up answer but you should know better. You didn't do your homework and just bought "go fast" parts. Come on, the spring manuf. will love you but I'd like to see you learn something. The end result will be springs lasting longer than 5K and you will have a big ol' grin on your face.

What *might* you have done wrong?

 

the only reason for breaking springs is crappy springs, you can have screwed up geometry and the only thing youll hurt are the valve guides, pushrods, rockers, cam, etc but at the end of the day the only reason for a broken spring is a spring that cant handle the application.

The 982s I purchased are THE top of the line spring as far as I know for stock sized spring pockets. I doubt you could find a better spring.

The napa springs were a LONG time ago, like 5 years ago before I had any money and I just needed to get by for a little while. The only thing that would screw things up for me would be installed height which is higher than it oughta be which in the case of the crappy springs probably saved them from breaking much sooner. Despite this, they allowed the engine to breathe well past 6000 without any problem.

My problem today lies not in broken springs but in that I went from K motions that had broken dampers to these springs that dont use a damper and are rated for much more than the old ones, are fresh, and may or may not be allowing me to rev past 5500 when before I did all this i could easily tach the motor to 6 even with broken dampers.

 

Don't rev up the engine with broken parts in the valve train. That makes baby jesus cry.

Explain your entire valvetrain, cam, lifters, pushrods ect. What were all the critical measurements? Something isn't right.

Sorry for lashing out in my last post. I had a feeling you were just throwing parts at it but your last post I see a different perspective.

 

well if i knew at the time it was broken i wouldnt have done that. The only clue I had was a ticking sound that i thought was a header leak that didnt go away with gaskets. I found the source after looking veerrrrry closely at the springs and seeing the inner damper broken on one.


The cam is an ssi cheapo 214/224, im running the cheapo summit 1.6 rockers, parts store lifters (sealed power?) stock length pushrods (7.8) heads have been milled ~.030, running the .015 shim head gasket. Has had two valve jobs.

I havent measured installed height, im fairly sure its taller than stock. Pushrod length looks pretty good.

Despite all this, the car has trapped 104.97 in the quarter with the crappy no name springs

I might add that is with an edelbrock carb which is a fine carb but the car really needs a double pumper which incidentally is coming to me in the mail sometime this week

 

Something is wrong with your valve train geometry but I don't know what. Can you have another local guy go over everything you did? Sometimes it is simple stuff but gets easily overlooked.

 

any one else have any ideas? Im gonna tear into this weekend but i dont even have any idea what to do next

 

Well I was going to say valve lash too, but it looks like it's been covered.


Btw, nice sig. 'tampered' lmao..

 

Looking on Comp's web site the 982 is listed as a conical spring (small seat portion and larger at the top). Check that the underside of the rocker arm isn't hitting the retainer.

RBob.

 

what is your whole set-up ignition-wise? I know you said you changed the cap rotor plugs and wires.

are you using a factoy hei module? is this triggering the MSD?

what kind of coil?

it almost sounds like the coil is getting weak up there, or you have some spark scatter. how do the gears look on the distributor and cam?

you're also using an edelbrock carb right? do you have a fuel pressure gauge that you can see at wot under load?

you probably have gone over all this stuff, i'm just trying to throw out suggestions.

from the build-up you've described, theres nothing that seems overly wrong, the cam is a mid-lift one, the valvetrain is the typical stuff.

how is the timing chain?

the reason i'm thinkin ignition and maybe some slop in the distributor is that you are now loading the cam more with heavier valvespring tension, changes the acceleration rates of the cam as it rotates, might make the timing jump around if something is loose. check the distributor for smooth rotation too.

if it were valvetrain related, you should be able to see tell tale marks on parts, either on the rocker, valve retainer, top of piston, etc.

can you get the engine to stumble unloaded? like in neutral? if so, you could pop the valve cover off, and put them little oil muffs on the valvetrain to avoid splashing oil, and look at the rocker with a timing light to see if they start flopping around at some rpm.

 

Im pretty sure ive ruled out ignition

Ive bypassed the MSD, no change

Ive changed the spark plug wires, no change

Changed the spark plugs, no change

changed the cap and rotor, no change

Changed the ignition module, no change

tested the ignition coil, good

tested pickup coil, good

I popped off the valve covers and tried my darndest to look and see if i was getting interference between the retainer and rocker. I even pulled a couple rockers, No interference as far as i can tell.

I looked closely at each spring, they all look fine

I looked closely at each pushrod they look ok

The carb is fine, air fuel ratio on my wideband is unchanged from before

The only thing I did was change valve springs and this problem reared its ugly head.

Is installed valvespring height really that critical? as I said before I was using cheapo valve springs that were actually shorter than the comp cams springs and the car ran great

Compression test when i did the springs was good

the only thing i can figure is maybe I got a faulty spring

the only odd thing I noticed with the valve cover off was that two retainers were different from the rest, the plateau after the bevel was wider on the top on those two but it wasnt interfering with anything, just a slight difference.

Also, when I got my box of springs, the box was sealed in plastic but inside the springs were quite oily and it looked almost dirty, im not sure thats how they are supposed to look, any of you guys used comp springs before and had them look like that? Maybe they gave me someone elses headache

 

Installed heigth is important to determine the spring pressures...I/e if your heigth is greater than spec, your pressures will be lower.
Was that motor oil on the springs? Usually they come with a light machine oil on them.

 

One more thing came to thought, did you remove the exhaust rotators? If so, you'll have to shim up to make up for them to keep the correct pressures.

 

So those 982 springs are designed to handle to .500 lift and you have .497 lift? I'd say that's your first mistake (buying those springs).

I highly doubt a spring that can handle .500 lift is the "best" spring that will fit a stock head. LT4 springs can handle .525 lift, and EX-612 (forgot brand..) springs are supposed to be able to handle like .600 I think. Don't quote me on the EX-612, but I know they are quite a bit better than the LT4 springs and still fit stock seats. The reason I know that is because I was looking at a set for my setup if I go with 1.6 rockers.