The 350's cam blank parameters are .310-.380 lobe lift with 108-112 LSA depending on grind. Here's the website: http://www.taperformance.com/proddetail.asp?prod=TA_ROL-350 You could get a 212 in roller version pretty close to the flat tappet version, but with more lift due to the cam blank parameters. You could also have them grind an "OEM" style asymmetric design, again with more lift. You could bump up the numbers a bit for a performance/stock hybrid type roller cam that wouldn't be so boring and still last you forever and a day. Gary
The CS647 cam has a really long and gentle opening ramp and even longer closing ramp for longevity. This is one of the aspects of stock type cams contributing to long valve train life that Gary has been talking about. As a result, even though the .050" intake duration is only 189 degrees, the .006" duration is a whopping 270 degrees. The intake valves closes 71 degrees ABDC so even at a static compression ratio of 10.2:1 the dynamic is only 7.75:1 Paul
In addition to this, the exhaust lobe sits at 208* @.050 and 293* @.006. LSA is 112.75* @.050 and 114.25* @.006. Cam sits at 3.25* advance @.050 while sitting at 1.75* retard @.006, which is also why it has a late intake valve closing point, when installing 'point to point' on the alignment dots for cam gear and crank gear, or 'straight up'. The cam is considered to have advance/retard built into it, not the gear. While it's almost impossible to get everything perfect, the geometric accuracy should give pretty close numbers when installing this camshaft and timing gear set, making it ideal for novice engine builders to assemble. Recall also what was mentioned about increased exhaust emphasis when considering the intake and exhaust lobe differences. While you can typically pay more attention to the .050 numbers on performance grinds in terms of power and RPM band, on wider profiles such as the CS647 the .006 numbers are equally important when determining power and RPM band. One of the reasons for this is air flow dynamics and the increased time it takes for air to move past partially opened valves when they are closing slower. What I typically do is take the figures from .006 and add them to .050 then divide by two to get an average. I believe this to be a more accurate way of getting true engine behavioral patterns than to simply use .050 numbers, particularly on wider pattern lobes, such as the CS647. You can even do this for more intense profiles, though it matters less the more intense it is, since the differences between the two sets of numbers decreases as those numbers become closer together (tighter pattern, or 'more intense' lobe profile with smaller differences between the two sets). This cam type makes for a weaker engine, but the tradeoffs mentioned earlier outweigh this when power figures aren't much less on equal dynamic compression comparisons. While I try to steer away from too many technical details as of late when describing this camshaft, now is a good time to fill in some more blanks to explain reasoning behind behavioral patterns. Valve timing events for the Federal Mogul CS647 cam are: 19,71,79,34 @.006 and -15,24,40,-12 @.050. Gary
You're thinking of that other smaller stock cam. There were two basic variants from Melling: the smaller one has a much earlier intake valve closing point (the one you're remembering), so it needs much less static compression to achieve its desired dynamic compression. The Federal Mogul cam CS647 has a much later intake valve closing point (because it is considerably larger), and so needs more static compression to achieve its desired dynamic compression. The second one from Melling is larger than this still, though not much, and is only about 2 hp/ft. lbs. difference between the Federal Mogul cam, with the Melling having 2 hp more and 2 ft. lbs. less. Powerbands would be similar between the larger Melling and the Federal Mogul cams. I prefer the Federal Mogul cam. There was another cam made by Federal Mogul that was similar to the smaller Melling cam, but it has been since discontinued as it was deemed unnecessary with the versatility of the CS647 cam, making it a rather moot point to continue its production. I hope this helps more than confuses. Gary
More to consider is wear characteristics. Everything is on its way to somewhere, and we all know everything will eventually wear out, but how will it behave as it is wearing out? How long will this process take, and are we willing to permit it to continue before something can be done about it? The faster something wears out, the less time surrounding parts have to accommodate the transition and can put additional stress on those parts, causing not only a domino effect, but a 'snowball rolling downhill' or exponential wear effect. Camshafts are hardened on the surface of the lobes, and this hardening only goes down so far. If wear extends beyond this hardened surface, subsequent wearing accelerates dramatically, until the lobe is round. Cam lobes can also become work hardened, but need extra time for this to occur compared to valve seats in the heads, which are hammered on with each valve cycle (which by the way the gentler this is, the longer THAT takes, and so permits a proper 'work in' process). This 'work hardening' can extend the camshaft's (and indeed the entire valvetrain's) lifespan even further. Having said all this, even the mildest cam will eventually wear out. The engineers knew this too, and anticipated it--even incorporated it--into the cam design, as they do with all their mechanical parts. There's more than one angle, or point of view, to consider when creating something. As the cam wears, the work hardening penetrates farther down inside the metal, so the camshaft actually 'repairs' itself as it is wearing out by virtue of the fact that it wears so slowly and gives time for additional work hardening. Slow wear also permits other surrounding parts to adjust/accommodate so the entire engine can wear in more evenly as the miles accumulate. This also allows smaller particles to exist which are easily filtered through a good oil filter, unlike chunks and shavings from a rapidly wearing, poorly thought out aftermarket cam design, which can further damage other engine components such as bearings and oil pump housing, crank surfaces, etc. As long as the oil is changed at regular intervals, and good oil is used along with a good quality oil filter, these stock parts are designed to last as long as possible. Change anything and you risk reducing the engine's life (sometimes considerably). When comparing these 'stock' cams to aftermarket designs and their corresponding wear characteristics, the aftermarket cams will eventually become as small as the 'stock' cams they are replacing, and as wear continues at its ever increasingly rapid rate, will become even smaller, so that after a reasonable amount of miles have passed, the 'stock' cam engine has more power than the worn out aftermarket cam. Replacement of the cam and lifters are minimal when considering other components that may be worn as a result when 'freshening up' an engine equipped with an aftermarket cam. The expenses and hassles begin to mount after a while. So whichever you prefer. Some people like to constantly fix things, or 'tinker' so whatever strokes your rod (engine pun). I probably left some things out, but I think this is a good mental meal for some people to digest. P.S.- Adding in some features that improve lubrication will extend the engine's lifespan even more, and can be done with any camshaft: 1) synthetic oil or oil additives that bind to the metal surfaces so cold starts are easier on the engine's components, where wear is at its greatest. Using 10w30 is recommended for most Buick 350's. 2) oil pump improvements such as a booster plate (which acts like an oil pump girdle, keeping clearances good even as temperatures increase and the housing expands), oil pressure regulator so oil pressure can be maintained at a safe range. 3) grooved cam bearings, ensuring more oil is delivered to cam surfaces to extend camshaft life, and 4) Crower's 'cam-saver' lifters, which have a small groove in the side permitting an additional 20%-30% more oil to bleed down onto the lobe and lifter face surfaces, increasing camshaft life, particularly at startup and lower (2,500 and below) RPM operating ranges. Oil pressure loss is minimal, about 1-2 PSI, which can be compensated with the aforementioned oil pressure regulator. Gary
I have a '70 block and heads and recently picked up some Kenne Bell Pistons that should match the GS factory compression ratio. Still mulling over what else to do with the car.
If have hi gears and stock converter, then this is true to an extent. If you have say 4.10s and a good converter,then this isn't remotely accurate!!!
So what would an engine on a dyno with no gears or converter do? Gears and converter don't make power they distribute it. Explain your thinking here please.
My old 350 and a friends were both ran w a milled divider and they were both faster Also on a flowbench a T/A dual plane w modified plenum showed much better runner to runner distribution Not everyone runs a 3700 pd car w dead gears and no stall Not picking on you as ive said over and over your car runs ell BUt each combo requires diff thinking is all
I think I can explain. No milled divider = better low-mid range power, and milling the divider is kinda like adding a small, 'single plane' feature into it, making it better for higher RPM. The former will produce better torque within its intended RPM range, while the latter will produce better power within its intended RPM range. It's really that simple. Even the stock intakes have a small cross-section between the secondaries for aided upper-end usage, while still maintaining enough for low-mid range, and since the intake essentially has a 4 hole spacer built into it, aids across the low-upper mid RPM ranges. With the stock cam (older design stock cam, which is larger), the powerband is very wide and it can make use of a small cross-section divider cut. This is why it doesn't fall on its face, even in low compression form, when using the SP3. It loses low end, yes, but still has some up high, just not as much as a larger cam that permits it to rev higher would. Now take a Crower level 3 cam (or smaller) for example, which is designed for a specific RPM range (about 1800-4800 RPM) will show greater loss up high due to its focus on that specified RPM band, and is the way of typical performance cams due to their very nature (more intense lobes for concentrated power within a certain RPM band, but less outside that--and the more intense it is, the greater the disparity). Put in a cam larger than Crower level 3, like say a TA 212, Crower level 4, or larger, and you'll begin to see the milled divider begin to have an increased benefit. The more flow demand the engine has, the more the milled divider will benefit it, since it is essentially a 'single plane' feature being built into a dual plane intake. Anyway, I hope this helps. Gary
I'll bet it depends on the lobe separation of the cam. If you have a sloppy 108 or 110 it might help. I would bet if you saw a dyno sheet with and without the divider you would see a large low RPM (torque) loss without much gain (HP) to speak of on top. Might give some over rev (RPM) capability but not actual HP. I think it's the butt dyno lying to you. Or the brain trying to trick you. "I've done work and spent money so it must be better" Nothing tells the truth like actual numbers. Milled divider did not work with the level 4 either. Same low end loss and no upper gain as with the level 3.
It really depends on combination, but the more air flow demand, the greater the effect of the milled divider (and is typically associated with higher RPM since the milled divider permits fuel charge crossover as demand increases). You used the level 4 with essentially the same environment that the level 3 was in, correct? I'm not disputing your results or conclusions, Steve, and I respect you. Gary
Before either of you guys get hurt feelings you both need to realize that Steve is running through un-ported heads and exhaust manifolds while more than likely Nick is running through ported heads and headers so not really an apples to apples comparison. ou: Derek
So then perhaps scavenging has more of an impact on it than the rest? Interesting, and ou: for not having thought of this before now. lol Thanks Derek, and makes a lot of sense too, seeing how increased scavenging would alleviate the reversion effect on intake charge and increase the benefit of a milled divider (and single plane too, for that matter). Gary
I run the cut down divider on the Stage 1. I like it compared to no mod. (Ran it both ways) Of course, I have cam, porting, gears, convertor, etc. So does TXGS and a few others.......... Probably should be on the SP3 thread but, oh well. I'd like to try an anti-reversion plate from Reher- Morrison.com Lots of duration and overlap with my setup.
No hurt feelings here. The reversion/scavenging effect is what I was getting at with the 108/110 lobe reference. Again, without actual numbers you have no qualifications to go by other then the butt dyno which to me means nothing. If I can find a local dyno I am going to have my engine tested before going back into the car. I will test both open divider and closed divider and we will see the difference in a mild build like mine. I do have time slips from the same track,same day both open and closed divider that show higher ETS and slower MPH with both level 3 and level 4 cams. With corrected A/F ratios for each. It's called testing people, not opinions.
But we already know what the results will be, for your particular combination, because you already told us (plus it's backed up by other data--data, not opinions). What you say is true, but this truth is not empirical for all combinations. This was the point being made. Take the results from your dyno runs and compare it to others' dyno runs where they have tested closed vs milled dividers and see what you find. Easier still, google is your friend. Other people out there have already done all this, and is where the 'opinions' are coming from, though they already have the actual numbers so no butt dyno needed. I explained the reasons earlier. I have a suggestion. Take the exact same combination you have now, but instead of the manifolds, no "X" pipe, and press bent exhaust, put on a set of small tube headers and an "X" pipe, retune and see what a (slightly) milled divider does on the dyno. :TU: Gary
