I recently read an article in a racing magazine about valve springs and read some pretty interesting things. One thing the guy interviewed talked about was about valve springs that dont have enough spring pressure for a cam. He said that they are much more likely to break due to strange harmonics that are created in the early stages of valve float. 978 springs running a closed seat pressure of 120# is not enough for big cams. Sure its close to the load of a 918, but dang near weighs twice as much. It also states that most valve spring failures are a result of an improper setup/selection of parts. I'm not saying anything bad about PP, just what the article states.

 

Werd.

 

When you guys talk about required spring pressures, an important piece of info is being left out, that is what rpm are you shifting at?, and where's your rev limiter set? I'm shifting at only 6200 rpm, rev limit set at 6400, so the required pressures for me would be less by a good bit then for alot of you. My cam is a 225/223, .580/.564, on a 113lsa, running the new Crane duals. Now take an XER cam and shift that puppy at 6700, it's way different. On a SpringMaster simulation (done for my cam), a 7000 rev limiter required about 50 pounds more open pressure than a 6500 rev limit. (~400 pounds versus ~350 using a 27% "safety factor")



(I just prefer to leave a little ET on the table and not shift at sky high rpm, it's a daily driver with stock rod bolts. I've not track tested my new cam yet, soon though.)

 

im in the process of installing these heads and im wondering if i should pull the 978's off and replace them with something else

i have the 918's on my stockers. . .


would this be a wise idea or do you think this is kinda a rare occurrance and i should just put them on

 

Tally, use CC 987s

 

ugh

not what i wanted to hear

 

I'm running ALOT bigger cam on my new PP LS6 style heads than you are (TSP 231/237) and I'm using the 918's. BUT.. I also ran the 978's on my other PP heads for about 6,000 miles with no problems with the .553 lift TR220

 

since i dont have the money for new ones, or the down time

ill probably put them on and see what happens, and if they go swap them to 987's

 

Cannibal.... why the 987s? They are a less expensive spring. What is the difference?

 

Yep.

To little spring pressure will cause problems too. It acutally weights about 46% more, and with less pressure that is a bad combo.

Bret

 

ok. with the ex-616 springs i shift at 7100 on the motor and 6800 on the spray with a rev limiter of 7150. yes, i hit the limiter quite often on the 1/2 shift

 

I never had any issues with my 987 springs on TEA SII 5.3 heads, TR224-112 on my old C5.

 

I'm about to install my PP heads, and this thread has me worried. I will install a Comp cam with a 232 XE-R lobe and Comp 1.75 rockers (not available at 1.70 unfortunately), so I am going to end up with 0.6125 lift on an XE-R lobe. I strongly suspect I should change springs before I install. The problem is, I have spent the morning trying to look at the Comp spring pages but none of three different computers and 5 different Acrobat Readers will open the pdf. I conclude it is toast. Can anyone point me toward or post the specs for the Comp 978, 987 and 977 springs? I'd rather not have to change lifters, but will if I have to.

 

Ok, i installed the patriot performance 5.3 stage 2 heads unmilled, with a LG G5X2 cam. i got about 75 miles on it, and broke 2 comp 978 springs. one intake, and one exhaust. the spring not only broke, they shattered, and shot metal all over in the engine, i found pieces of spring on top of the cam, and in the oil. when the springs broke, i had two valves hit pistons and ding them up pretty good, but i just buffed them down with a dremmel tool so they wouldn't cause hot spots. i contacted terry, and after talking a while, he sent me a new set of heads. the problem i had with it was, i am by no means a mechanic, so that is why i paid a guy 600 bucks to put in heads and cam. i couldn't afford to pay to have it torn down again, and patriot wouldn't pay to do it either.so i took a big chance and tore it down, and after a couple weeks of working a couple hours each night and taking my time, i got it all apart. i am not going to say how much i was compensated, but lets just say after having to buy new coolant, and different gaskets(not head gaskets, terry sent them) and 3 oil changes to get metal pieces out from the springs, i ended up paying about 40 dollars, for all my troubles, insted of being paid for my troubles. as for the product, i can not vouch for its performance yet, so i am not saying anything about the product itself. but i would go with crane springs, and will if i break these 978's. but i was dissappointed with the customer service aspect and all the calls i had to make, cause i had to put the money out to fix the car, cause they took there time with the compensation. i think it was an upper managerial problem, not a problem with terry. sorry for the novel, just my .02 cents.
so in all i ended up paying a lot more than 1299 for the heads, in time, parts and elbow grease.

Thanx for your help terry i am glad you backed your product. hopefully when i get it broke in, i will have some results.

 

You guys that broke these comp double springs are you absolutely positive you clearanced your rockers from the retainers. And also spec'd out every spring to get the correct install height?

 

I'm running Yella Terras so there are no clearance issues to look at. The install hieght was spec'ed out by the porter/assembler and should be right.

 

there was no evidence when i took it apart of the retainers hitting the rockers. and also they said the springs were set at 1.8 instead of 1.85" and coil binded.not trying to start flames, just expressing my personal experience.

 

has anyone broken a manley spring?

 

I had Revs at first... broke 3 of them (two driving and 1 more removing them to put the revised REV springs in) and since then no problems... the car feels stronger above 6000 now too with the new springs so feels like less valve float... so im gonna stick it out with REV and see what happens! Luckily both times the spring in the first batch broke the 2nd spring kept the valves safe!

 

I dunno about putting a g5x2 with these springs, that cam is rated to what? .609? these springs installed @ 1.86~1.87" only allow for .600 lift, so you are really pushing that with these springs, i'm not surprised at all that you broke it, my cam is 232 .595 and it took 3k miles with the rockers not clearing.
Next summer i'll probably end up trying the cranes and see how well they hold up, or whatever terry has out then.
-Steve