I pulled my valve cover today, measured valve gap, intakes were .006, down .003 from the .009 I set them at over 3 years ago. Pulled the cams to remove the tappets, and that's when I realized that the springs for both intake valves were broken. These are dual heavy duty valve springs from WEB, with the shim-under conversion. Both springs on the left valve broken, and just the outside spring on the right one. One of them was broken into 3 pieces!
None of the exhaust springs were broken.

Had it not been for shim-under, the shims may have been lost in the head and most likely tore up cams, and who knows what else. But then again, if the springs were better quality and didn't break, shim-under would have done no good. Its six of one, half dozen of the other.

I suppose the intakes broke where the exhaust did not, because the cam lift of the intake cam is much higher than that of the exhaust. almost 30 thousandths more. seems the WEB springs could not handle the compression. When I bought them, I told them my cam lift, they said they'd be okay. Did the lift brake them, or can accidental over-reving cause this?


But hey, at least my head and cams are okay, now for a valve job and new springs.....
Obviously I do not want to put the same Web springs back in. But I really like having the shim under. Don't want to buy it all, but may have to, cause its doubtful anybody elses springs will work with the Web retainers, and who knows if length would be right.

 

Good to hear you did not have some other expensive parts damaged, maybe that new light weight piston will be a little easier on all the other components.........[img]i/expressions/face-icon-small-wink.gif[/img]

 

I've got shim unders with KW springs for shim unders. I don't know if there is any difference between the brands. I've twisted mine way past where the tach stops reading and its held.

 

HT, check out the regular dual springs from RWR. That's what is in my motor and they were the exact same ID and Length as the shim under's from Pami. I am using them for my shim under's now. They worked GREA!!!!

Absolutely no difference at all in my case.

I had assumed that it was the same for everyone.

Those duals are the only thing not HPR in my motor. They were perfect. In fact, the exact same shims and retainers are used.

Good luck man. And good thing you caught it before something really went kaboom.

BD

 

I am getting some of those Web Shim Unders also, I was told by a few motor builders that will save me bucks down the road

 

as I read more old posts about valve springs, it seems that there have been many cases of springs breaking from every supplier - pami, rwr, web, you name it. from what others are saying in these old posts, once you get into race cam lifts of .425 and over, any and all springs will eventually break if not routinely checked for weekness prior. as the springs get more used, their tension decreases, and then valves float and start slamming shut, and then the fractures occur. mine have been installed for almost 4 years, and although I routinely check clearance gap, I have never pulled the cams and checked the spring's strength.

I guess from now on, I will inspect valve spring tension along with gap checks regularly. wish Ida known this sooner. but nonetheless I did successfully find a problem before serious damage resulted, luckily though.

Bigdaddy I will check compatability of rwr springs with my web tappets and/or retainers, thanks.

 

so now that we're on the subject of spring tension inspection, anybody got any good ideas on a way to measure spring tension without removal? some sort of scale handheld pushed against the tappet with cam removed, and easily read would be ideal.

 

after my head grenaded I was told to change springs evey year, mine were 3 years old.

 

There is a tool that machinests have that is table mounted and can measure pressure. Not something that you can go to sears and get though.

As far as replacement goes. Obviously replacement times would be different for different people. If you build up a ton of hours each year on your machine, a yearly change might be in order. If you only drag, and your out 5-7 times a year, I should think every two years would be adequate. Mine are 2 years old, but I've only had the HPR3 cams in a month. I will be replacing my springs this summer.

 

All the Co.s use Kibblewhite product !!! Check for coil bind and check your installed height with mfg. spec !