I have about 3 days before my stage2 tri-flow cams go on,i was wondering what kinda gain and differences would there be to adding the valve springs to these cams??

 

upgrading the valvetrain is an important thing to do when putting in a bigger cam....and since you have the head off the car already, I would definetily upgrade the springs.

 

thanks for the input,just gonna check with the shop tommorro to see how much more labour for the springs

 

This is a copy of my post off of the 'other' board. Educate yourself.

The ramp rates and lobe profiles of a cam determine just how hard they are on a valvetrain. You can have two cams of the same duration at .050, with the same lift, but one will put significantly more stress on the valvetrain. It's all in the lobe profiles. The faster the ramp rates (open/close) the more stress there is.

Think of it this way: Every time your valve opens, your valvespring is forced to compress. The faster it's forced to compress, the more stress is put on it. On the flipside of this, the faster your valve closes, the harder that valve slams into it's seat in the head. It's not uncommon for a valve to even 'bounce' off of the head from slamming into it so hard with super-aggresive profiles and fatigued, or even new valve springs.

Ultimately its not duration, lift, or overlap that create stress in your valvetrain, but rather a product of the cam's ramp profile, rpms, and maximum lift involved. Remember, stress increases exponentially with RPMs. Reference this video and maybe you can understand just how hard a valvespring is forced to work at high rpms. (Huge file) http://www.offline.org/~burch/valvespring.avi



Next topic: Lopey idle. Lopeyness of a cam is caused by overlap. Larger int/ehx, LSA, and/or lift numbers do NOT make a cam lopey. You can have a ginourmous cam with no overlap, and it will sound remarkably close to stock. The formula is as such:

Add the Int and Exh duration .
2. Divide that number by four
3. Subtract the lobe seperation {LSA} {LCA} of the camshaft from that number
4. Multiply that number by two
5. Overlap

Int 237 + Exh 242 = 479 / 4 = 119.75 - 112 Lsa = 7.75 * 2 = 15.5 overlap



Overlap causes lopeyness in idle. That burble in a four cylinder, or the lovely potato-potato lope in a big V8. I hope this clears up some common misconceptions

I'll go into valve springs and cam lifts in the must basic way I know how.

There's two types of lift (generally) you need to pay attention to. Cam lift, and net valve lift. Cam lift, is the amount of lift that is ground into the lobe on the cam. This is multiplied generally by the ratio in the rockers that transfer the ups and downs ground into your cam, to your valves opening and closing. The amount your valves open and close is your net valve lift.

Now that we have that cleared up, your valve springs are only good for a certain lift. But how do I know how much, you say? Well, your valve spring, as set up on your head, will be at a certain height, as measured from the base of the valve spring seat. Lets say your installed height is 1.800". Now, your valve springs coil bind at say, 1.250". What does this mean? When your valvespring is fully compressed, the coils in it will be stacked on each other and touching at 1.250", thus this is a far as the spring can be compressed.

So we take installed height (1.800") and subtract coil bind (1.250"), this leaves us with .550". This is how much of a margin you can play with for net valve lift. Now, ALWAYS ALWAYS ALWAYS subtract .050 from this number for thermal expansion, and stress reduction on your valve springs, so we have our .550" - .050" = .500" of net valve lift can be run safely on these springs without causing mechanical failure.

This is the most important part of the spring equation, the other part below.

Spring PRESSURE. Spring pressure is the amount of pushing pressure your valve springs exert when set up on your head.

With new valve springs, the MFR will provide you with specs on the springs. This is how you can figure out the spring rate, of any particular spring. You will want a certain spring rate to accomodate certain radical camshafts, and less spring rate for more docile camshafts, all to facilitate less stress and wear/tear on all parts involved. Example:

Diameter: 1.460 in.
Pressure at 1.850 installed height: 155 lbs.
Pressure at 1.150 open height: 450 lbs.
Coil Bind at: 1.085 in.

To find the spring rate of a spring: 450(open spring rate)-155(installed spring rate) / 1.850 (installed spring height) - 1.150(open spring height) = (295)/(.700) = 421 lb/in

So, our springs provide 421 pounds of pressure, per inch of compression.

Now find the difference in installed height - lets say your springs sit at 1.900 instead of 1.850: 1.900-1.850 = .050 inches

Calculate load change for .050 travel : .050 in. * 421 lb/in = 21 lb, so seat load @ 1.900 installed height = 155 - 21 or 134 lb.



Complex, but simple once you learn what your working with. Makes it easy to decipher the differences in specs from different vendors, and to compare springs side by side. The amount of spring you will actually need will depend on your setup. Too much spring will cost you power by parasitic loss and cause extra wear on parts. Too little spring will not be able to adequetely control your valvetrain, and you will lose power (and potentially smack a piston with a valve) due to valve float. The goal is to find the ideal combination.

 

awesome info spinner

 

indeed! thanks for taking the time on that great write Spinner.

 

are these cams designed for boost or no?

 

Yes. Very good write up indeed.

No offense intended, but knowing the math, how the math is figured, and knowing every detail about the cam is good to know, but it does not tell you how to pick the right spring for a given cam. This takes years of R&D.

Any cam company who's worth anything will know what springs are right for the cam you choose. Ask the cam manufacture. They'll know which spring is right for you, and may even sell them.

 

these cams were made with our stock springs in mind,if not JBP does sell springs to take your cams to the next level

 

That's cool. And pardon my ignorace, but who's JBP? Just for future use so I know who to get parts from.

Thanks.

BTW, anyone who's doing this on a car with a few miles on the engine should spring for new springs (pun intended ) even if you stay with the stock springs.

 

www.jbodyperformance.com

 

so what website did you get these cams? i was thinking for my 2.2 to get the obvious intake and exhaust. but was wondering if cams and springs are all i need for an extra power upgrade. im not a cams guy but just wondering how many more upgrades would be needed to make it reliable?

 

will the valves clear the diamond pistons with that lift of the stage two cams

 

The added lift of the stage II cam is not available yet , but I'm sure that the extra lift is slight (because of our sensitive ECM) so you should not have any problems.

Super post Spinner! The only thing not covered is valve seat width and seating. The narrower the valve seat, the more pressure per square inch exerted, so the better the seal - up to a point. Very narrow seats .8-1.0mm is best for use in drag race engines, but they have a very short life. Wide valve seats (1.8-2mm) are good for road race engines because of their durability.

Your normal street engine should be somewhere in-between, depending on the strength of the springs. New valve seats should always be cut after new valves/guides are installed. The more metal removed on the valve seat changes assembled valve heigth, which is adjusted by shimming the valve spring seats that rest against the head to even out the valve seat pressure.

When installing larger valves, the valve seat must be adjusted so it rests in the center of the new larger dia. valve face by use of inside cutters on the head and in the port. 5 angle cutters are neccessary for this purpose, not just the common 3 angle cutters. Even if you are not going to bigger valves, 5 angle cutters should always be used on race engines to ease the air flow past the valves. This is especially critical at low lifts.

By the way, never lap a stellite (or any other) coated valve, as you will wear away the very thin, yet hard coating, greatly shortening the valve's life. Personally, I don't believe in lapping valves at all, as this forms microscopic concentric rings in both the valve face and the seat. These grooves seal great when the valves are cold, but because the valves and the head expand at different rates when hot, these tiny grooves no longer match up, creating leakage. Just use a very light hand pressure with your standard new-way or quick-way cutter and leave it at that. A superior seal will form by allowing the valves to seat-in by themselves when the engine is run. I've seen race mechanics use a hammer and a drift to accelerate this process (de-burr the seats,) but would advise against it.

 

The Upgrading of springs will help to keep from floating the valves at higher rpms. Also, the stock springs were only designed to accept so much lift, so the upgraded springs will allow you to go larger lift without having to worry about coil binding. We sell the Ferrea Valve springs, they are a dual spring design and have had great luck with them. We also sell all Bates Engineering products as well, as we have had great luck with all there products as well, both personally and for customer vehicles. Hope this helps. You can check out some of the products on our site.

 

That was good info....but I hate to say that overlap is not the ONLY determining factor in the idle quality of a cam. Duration has a significant impact on the idle quality. All of this combined with lift and the valve timing events creates the idle quality. I do agree that overlap is a major contributing factor....but not the only contributing factor

 

Agreed, but why four months later?

Other contributing factors are intake centerline, when the intake closes after TDC, ignition base timing, fuel mixture, length of the primary header tubes, engine size, firing order, intake manifold design, etc., etc.

The true cause of this "galloping" sound is from reversion of unspent exhaust gases being pushed back into the intake manifold as the intake valve is first opened. The cylinder pressure is higher than the intake manifold, so the piston literally pushes exhaust into the intake manifold and dilutes the intake charge.

Valve overlap is certainly a contributing factor, but not the only one.

Using a single plane intake manifold (where all runners share a common plenum) will cause rougher low-rpm running and a penalty in torque production until the air speed and overlap tuning effect overcomes the tendency towards reversion at higher rpm. A dual plane lessens the effect and increases low-rpm torque production.

I once had a '71 Nova with a SBC 350, headers, single plane Holley intake manifold, 750 vacuum secondary Holley carb, Crane "Fireball" solid cam with 302* of duration and .510" of lift. I bought an adjustable MSD timing control unit just so I could retard the timing while cruising around town, and get that cool idle sound. Retarding the timing sounded great at idle, but the car couldn't get out of its own way. Advance it and the idle smoothed out a lot (sounded boring), but it came on the cam quickly and ran like a raped ape.

I could go on and on, but I think most of you get the idea.