lokoRS

Heres the deal... I got TF 23* heads with the dual valve spring option that can handle up to 600" lift. Im trying to choose a cam for my super ram 350 and the one that looks like its in the powerband i want is the compcam xr276-12, but it has 503/510 lift but i want more lift. They have a custom grind lobes with the same duration and lsa but would give .567/.584 lift with 1.5 rockers, which means it has really, really aggressive ramps. My question is, can these springs handle it? And what kind of lifters can handle this so they wont collapse under the pressure.
This car is my daily driver so reliability is an issue.

Stekman

There is a lot more to a valve spring than how much lift it can take. What is the open pressure? What is the seat pressure? What is the spring rate? What is the coil bind? What is the installed height? All those determine what the spring can and cannot handle. As you say, it can support the lift, but if it has a wimpy seat pressure, you will encounter valve float relitivly early in the poewrband. If you run too much spring pressure, you risk collapsing the lifter. As a general rule of thumb, i don't use springs that come equipped on cylinder heads. I have seen one too many stories of factory-equipped springs breaking and doing damage. If i get a cam, i use the springs that are recommended by the cam manufacturer, no questions asked. That way, i am certain that i have enough lift, spring pressre, and every other aspect of a valve spring.

Another thing to think about, i believe the cams you are looking at are hydraulic roller cams. If thats the case (or if otherwise, but still), lifters are lifters. It's not like there are "high lift lifters" or "lifters designed for high spring pressures." For the most part, a hydraulic lifter is a hydraulic lifter. if you are concerned about spring pressures, run a solid roller, and get some gigantit spring.

As for lift, how does ~.537" on the intake and .544" sound? Thats the XR276 with 1.6 ratio rockers. Again, you want mega lift, get a solid roller. Keep in mind, the more aggressive the ramp rates, the bigger the beating the valve springs undergo. I would go with the XR276 and 1.6 rockers.

Another option is to call Comp and talk to them. They've been in business a fair amount of time. I'm sure they know a thing or two about cams and valve springs. But then again, they would tell you to run their recommended spring as well.

ede

the springs that come on the heads aren't really that good of a spring. considering the low cost of springs compared to the damage one an cause when it fails i'd buy springs to match the cam. i'd also only buy springs from comp, lunati, or crane and stay away from springs from GMPP, k motion and any unknown springs

lokoRS

With that cam , is it necessary to get the 10deg locks and titanium retainers? Im getting the Comp 987 springs. I want to be able to spin it past 6000 rpm when i need to.

lokoRS

Alright, everyone's so quiet....
Here's a more specific question. I decided that im gonna get the titanium retainers. But there is an option to get the standard size or +.050 installed height. What does that mean? My assembled heads came with 7 deg locks with +0.050.
Does this mean i have to get the +.050 size also?

RB83L69

In order to answer that question, you need to know 2 things: the installed height of what you've got; and the installed height you need with whatever springs you get.

Longer valves, or + offset keepers, give you mroe installed heignt, which allows more spring, more lift, or both. But if the springs you get require a lesser installed height to get the seat pressure you need, then you don't want the offset.

You need to know more about what you've got, what you want, and all that.

IMHO the more aggressive cam is too much for a street motor that sees daily driver duty. For springs that will stand that kind of lift, look at ones for solid roller cams; you'll want 125-140 lbs on the seat, and about 400 on the nose (max lift). Not an easy combo to get in a 1.45" spring. But very easy to get in a 1.55" one.

But I don't think you need that much lift with those particular heads; in fact the XR276 with 1.6 rockers will give you right about .530" of lift, which will fit with the 987 springs IF PROPERLY SET UP. They will give you 125-130 lbs on the seat and about 360 open, which is a good match to a hyd roller.

If you're going to $pring for the titanium retainers, get the 10° +.050" ones; and an assortment of the hardened steel shims in .015", .030", and .060". Personally I'd rather have too much installed height and some shim, rather than not enough installed height woth the spring sitting directly on the aluminum (which is a combo that will not last long before it destroys the heads).

If you want more insurance for higher revs, look at a rev kit.

Stekman

Notice the installed height in the image, that is what it refers to. By getting a +.050, you are pretty much just adding to installed height.

Titanium retainers, yes they are nifty. Not really needed for the street. Most of the time, for normal street duty, standard steel ones from Comp work fine. Nothing wrong with titanium, though.

Another thing that increased installed height does: it lessens your seat pressure. With 987 springs, i don't thing it would hurt to much, considering it's a slightly stiffer spring.

On a side note, just because someone hasn't resonded in 5 hours, doesn't mean its "quiet." Some people dont't "live" on TGO...

*edit* damn you RB and that bastardized keyboard of yours.

cali92RS

I am also gonna use the xr276 cam, and it does recommened the 987 springs in the catalog, however in their spring chart it says max recommended lift for the spring is .500. Is that a typo? it seems low to me.
http://www.compcams.com/Technical/Cu...ML/340-349.asp

Stekman

Well, the coil bind is 1.150" and if you follow the 1.800" installed height, thats a difference of .650". Take away the .060" "safety" margin, give or take, you get high .500's for total lift. That and it's the recommended spring for cams with well over .500" lift. Note that it is a recommended spring for the Xr300hr, and that has .580" lift with 1.5 rockers.

Of course, your installed height ultimatly dictates the maximum lift you can use. But there is a lot of flexibility with the 987 springs before max lift becomes an issue.

cali92RS

I never did understand the spring portions in my dynamics class.
So the moral of the story is get what the cam manufacturer recommends... i guess

Stekman

What heads/valves are you going to be using?

cali92RS

Same as lokors, tf 23* heads