Getting ready to replace intake / head / exhaust gaskets and would like to do some upgrades while I'm in there.
However, since I've been looking through various websites and catalogs, all I'm getting is more and more confused.
Now,
Rocker arm ratios, looks like there are 1.5:1 and 1.6:1. What's the difference?
What pushrods should I get to compliment the new rocker arms?
Can I put hydraulic lifters in it?
After above components, will my stock valves be ok? Or should I replace them as well?
When installing new valvetrain components, will my stock valve covers still fit?
When looking for a camshaft, what am I looking for if I want good power off the line? And is there a cam that will also give me good midrange power?

And any other considerations that I'm missing, thoughts, opinions and harrassment would be appreciated.

 

The 1.6 locates the point of contact on the pushrod closer to the fulcrum (I think it's called a fulcrum). This makes the rocker arm push the valve down further allowing more air in, and more power. Not much more, but something.

Hardened pushrods are recommended, chromemoly would be best, but they are expensive.

Yes.

The smaller the LSA gets, and the bigger the duration gets the less street friendly it becomes.

You might want to look at valve springs too.

 

LSA? Lobe Separation Angle?
Explain duration please?
I was wondering if valve springs would make a difference. Higher tension?

 

You mainly need valve springs so they can handle the lift the cam gives, otherwise the spring will basically "bottom out" and break. Then a valve drops, destroys the cylinder, so on so on.

Duration is how long the valve will stay open for in degrees. There are two different sets, advertised duration, and duration at .05" lift. The .05" lift is the one to pay more attention to. The longer the duration the less street friendly it becomes.

EDIT: Are you the one I helped with understanding injectors?

 

Yup. Ready to roll up your sleeves and get dirty again? Cuz I think this promises to be another long conversation.

 

Let's do it!

Well if you want to know what duration/LSA is, than here is the basic stuff.

Lobe Seperation Angle (LSA) is the average between the intake center line (ICL), and exhaust center line (ECL). So if I have a camshaft with 112 LSA, the intake center line is somewhere like 108 and the exhaust center line would be 116. Averages out to 112. Lower this number, typically the rougher the idle.

Duration; how long the valve stays open in degrees to the camshaft. The camshaft has 360 degrees obviously. If the intake lobe is open for 230 degrees, well than it opens the intake valve for 230 degrees of the camshaft.

 

By centerline, you mean the peak of the lobe?
Why does a lower LSA make for rougher idle?
What determines how much power increase you get? And at what RPM range you get it at?

 

The LSA is the measure (in degrees) between the top (center) of the two lobes. The lower LSA in lower RPMs make a rough idle because of how the exhaust and intake valves open. They have more overlap which causes a rougher idle, and also creates more power down low.
That depends on a lot of other things too. Here is a good site to get a basic feel of things.

http://www.wallaceracing.com/cambasics.htm

 

My cam pulls to about 6700rpms. You don't want to spin a stock (bottom end) motor past 7000rpms (unless you wanna break stuff). I've been told that you can't have over .530 lift on stock heads. I'm not sure how true this is but I wasn't about to try.

 

"down low" - You mean lower rpm's?


Ok, how do you judge what springs you want to install?


By "street friendly" do you mean how rough the engine runs?
Like with the low LSA=rough idle?

 

Does the cam also control the amount of lift?
If so, are lifters, rocker arms, and pushrods a consideration when choosing a cam?
218/218 .528/.528 112LSA 112IC
What is this number?
And this one?
And this one?

Does the cam control the lift?
Does anything else change the amount of lift?

 

The camshaft sole purpose is to control how much life lift the valves have, and when the valves open.

the 218/218 is the degrees (duration) of each lobe. The intake lobe is first, and the exhaust lobe is second. Usually it is a good idea to have a longer (bigger number) exhaust duration since the valve opening is smaller.

the .528/.528 is the lift in inches. The camshaft lobes opens the valves .528". Again, the intake lobe is first, then the exhaust. Also a good idea to have a higher (bigger number) exhaust lift.

I have not seen the 112IC before, that stumps me. If it is refering to Intake Centerline, than it should be smaller than the LSA since the LSA is the average between intake and exhaust. But I am not sure what it means.

"down low" means low RPMs, yes.

To decide on springs you need to look at the lift of the camshaft PLUS the ratio of the rocker, first. Most camshafts advertise the lift with 1.5 rocker arms, which is fine if you keep 1.5, if not than you have to re-do the math to 1.6 or 1.7 or whatever the ratio is. Let's take the .528 you have above, and I am going to assume that is with 1.5 rockers. Just to keep it easy we won't do other ratios right now, but we now need to find a spring that can take that amount of lift. To find how much lift the spring can take, you take what the install height will be on your car (NOT THE ADVERTISED INSTALL HEIGHT) and minus the coil bind. An example...

Say spring X has coil bind at 1.100" and I am installing it at 1.750".
Take 1.750 - 1.100 = .650"
Now take another .060 off of that number. .650 - .060 = .590"
Now you have the total lift that spring can support safely, which is .590 inches.

Spring rates I am not sure about on v6 cars, but LT1's are somewhere around 90-125lbs at installed height, and 300-325 at compressed height.

Street friendly mainly means the rough idle, and how much gas it uses.

Have I lost you yet?

 

112IC is the intake centerline. The 3.8L uses 1.6 rockers. I love this cam and can't wait to get it tuned (saving for injectors right now). It is gas friendly as long as you don't drive fast, lol. If you get on it, gas goes like the wind, otherwise it's about the same. My last 2 tanks of gas I filled it all the way up and played really rough and got 250 miles on the tank, then I filled it halfway and drove normal and got 250 miles so I'd have to say your driving habits when cammed affect your mileage A LOT! I have 105# springs on the car now, comp cams told me that they are good for the lift and rpms I'll be utilizing.

Abut your questions about does the cam control the lift... Yes, the cam controls lift. The lopes press against the lifters which push the pushrods up into the rocker arms which compress the valvesprings and open the valve.

That's all the stuff I got for mine.

 

I think I'm with you so far, so here's some more for ya...

Low LSA = low end power, bad idle

Covered what duration is, but how does it affect the performance?

Same with lift, what is the effect on performance?

And, found another term. Flat Tappet. What does that mean? Mating surface from cam to lifter?

Does it require other mods to install roller lifters and rockers?
Figure if I'm gonna do this, might as well get those since they're supposed to reduce friction.
And, since it does reduce friction, that's more energy going through the mechanical connections, ie pushrods, rockers, valves... so question is, with rollers, should you get stronger springs? That question pertains to changing only the lifters and rockers, not the cam. I understand that you need springs if you get a higher performance cam to keep the valves from slapping the rocker and causing bad headaches.

 

More duration and more lift = more air and gas which in turn makes more power.

I am pretty sure you're car already has roller lifters. LT1s do, and I would assume the same with v6 cars, but I am not sure. Yes flat tappet refers to the matting surface of the cam lobe to the lifter. It does not require extra stuff to replace the roller lifters. Just pull the old ones out, and put the new ones in.

I would suggest a package deal, like what camabird posted.