spring pressure
 

With all the huge spring pressure being run on stockers, can you ever have too much?? If so at what point and does it matter if the combo is a low rpm vs high rpm combo??

Re: spring pressure
 

Don't have a stocker, however I believe that spring pressure is all about control. You run enough to control the valve and valve train, running too little pressure seems to cause damage, locks,retainers, even lifters. While running too much would seem to create it's own set of problems, though in my opinion not as problematic. These are just my thoughts gained from observation.I'm sure there are a few knowledgable folks on here that will share their experience. Joe

Re: spring pressure
 

Cam Profiles determine in most cases the spring pressure needed, along with the weight of the Valves, retainers and locks! Thats my story and i'm sticking to it. Merry Christmas!

Re: spring pressure
 

So rpm is not a major factor????

Re: spring pressure
 

RPM is a factor of cam profile, which determines the RPM at which the engine makes HP and torque.

The question you're asking is extremely generalized, and the answers given are about as good and as complete as is possible.

Just to add a little. A lower RPM profile might be more radical, because there is something else limiting RPM, and it would therefore require as much spring pressure. In other words, if a given combination is RPM limited by something other than the cam profile, a more radical cam profile might be used to make more power at that lower RPM.

Clear as mud? It's hard to explain in a post on an Internet bulletin board, as there are time and space restrictions, and a proper dissertation/explanation would take up far too much of both. It is a very complex subject.

Re: spring pressure
 

Thanks all.

Bottom line then is a radical cam needs A LOT of spring pressure regardless of rpm range???

Re: spring pressure
 

i have been adding shims along the way this year and the motor has liked it each time i did it. F/CM 350 ci 330 hp. shift at 6500 and cross at 7200. i haven't heard the coils binding yet, so i am going to add another shim under the exhaust side for the next race and see what happens :-) i love this sport!


i look forward to the day i cross the line and the car shuts off and the parachute deploys automatically....in my stocker! LOL

Ian

Re: spring pressure
 

So, what kind of pressure are you up to???

Re: spring pressure
 

So what does coil bind SOUND like? :D

Re: spring pressure
 

Dink, dink, dink, dink, ......

Re: spring pressure
 

it sounds a lot like the head of a valve coming out the header collector.

Re: spring pressure
 

Ahh, you have gone too far too! My "valve through the exhaust" sounded like a death rattle at 1100 feet. Ended by splitting the piston in two, one half embedded in the block, half way up the bore, the other half scattered throughout the other 7 holes!

It was actually caused by coil bind, but I'd imagine similar results if it did happen.

I have been increasing valve pressure buy .01" shims and am up to .06" intake and .03" exhaust over recommended and each time I add shims the car picks up. The next race I go to I will be matching the ex with the intake. It is a largerjump than I've done so far, but I am guessing it will be good as I did the intake first and have been catching up with exhaust with good results. I've discussed this lots with my engine builder and we decided to go with the idea that more is better, to the point we wipe the cam shaft out. This will be season two coming up, the last cam had three seasons without fail. As far as telling you what my spring pressure is, I don't think it matters. My combo likes the springs stiff. Just like valve lash, my combo runs near to zero as I dare go... I set them cold and I set them tight. But that's for another thread I am sure.

What I will tell you is at what spring pressure I wipe the cam out...if it happens. I switched Joe Gibbs oil this past seaon, this is the first time I am not freshening my engine, everything, including the cam looks good. I figure I'll get to coil bind before hurting the cam.
Ian

Re: spring pressure
 

Your kidding about "getting to coil bind", right? .050" from coil bind should be close enough.

Re: spring pressure
 

Ed,
Don't you remember...?? You want it to coil bind just as it reaches the peak of the "Loft" or "Toss" off the cam profile?

Re: spring pressure
 

Guess I've been doing it wrong

Re: spring pressure
 

Ed
Here you go again. You missed it. You put in a safety factor of setting it up to get .05 before you get max lift. That way you cant ever float the valves. Ive been doing this for years and I aint never floated a valve. Well wait a minute I think I floated a couple out the headers. HeHeHe
reed

Re: spring pressure
 

Yeah, no one does that anymore, it's so "2010".

Re: spring pressure
 

Us old guys have a tough time keeping up. :-(