Sadly, this shows just how ignorant people who claim to know so much about these engines actually are. Just keep building your 10k mile engines then. I won't waste my time anymore here. My input is clearly not wanted, and is outright ridiculed. Gary
Everyone's input is valuable. We are all here to learn or contribute. Hopefully folks can ignore the contests of credibility. My opinion is that the factory engineers have the greatest resources, and do a damn fine job considering they aren't in a position to give you their best efforts. Things like... 1. Cost 2. Assembly line cannot stop 3. Has to make it through the warranty period, and 4. Planned obsolescence... would have greater importance to the company than the engineers' best efforts.
I know you're not talking about me because I try to get people to go with a roller cam when I build an engine for them. If they don't want to go that way then that's on them. Plus I'm all about adding cubes to any build I do. For a sbb 350 a stock cam just wouldn't be able to keep up with the extra cubes, it would add gobs of low end torque with the extra cid though. And I for one appreciate the time you take writing about the stock Buick cams, but they just can't get to the HP level that people want their engine at. It would be nice to know what kind of potential a stock cam would have on a set of fully ported heads with small stem valves and 2:1 rockers to see if one can squeeze out more HP and torque? With the extra spring pressure to now control the valve with the 2:1 rockers will a stock cam still be "gentle" and still have good longevity? You need to remember that the majority of people here on v8 have these cars for the hobby and not looking to build a daily driver that needs to last for 500,000 miles. If the cam wears out that gives the hobbyist the excuse to go out into the garage and install a new cam, or even an excuse to build something different. I had to laugh at the .380" lift, it does look a bit anemic compared to a performance cam, is that the actual lift of a stock sbb 350 cam? Don't take that personal, you didn't originally design that lift. Derek
A .380 lift cam has 84% of the lift that a .450 cam does, and with the asymmetric lobe design keeping lifts there longer, the .380 lift cam makes up for about another 10-15% of that, so...you do the math. It's pretty simple. As far as hogging out the heads and trying to get the stock cam to perform with that, not so much. Is it any wonder why people get poor results with their builds with such a mismatched suggestion? Anyway, I made my point, and no it wasn't directed at you. Some things I thought would be obvious are apparently lost on many people, but it doesn't matter. No 'hot rodder' would ever be interested in my input anyway, which is to be expected. Gary
I always get very good results with any engine I build from a sbf 302 to a 347 stroker, to a BBF 460 to a 521 stroker to a sbc 350 to a 383, sbc 400 to a 434, a small block Mopar from a little 340 to a 414, BBC from a 454 to a 496, Pontiac 400 to a 460 and every standard rebuild version of the listed strokers plus standard CID rebuilds of engines not mentioned. (ALL ROLLLER VERSIONS except the Mopar, THAT ALL RUN VERY VERY WELL) What have you built? The question was in the spirit of the thread to see if a stock cam is worth exploring beyond the limits of its blueprinted version of the sbb 350 HP output. Instead I get a snide comment attacking my abilities. To me your roller version of the stock cam would be more interesting than the "stock" flat tappet cam replacement version and still waiting for you to post those specs, unless there top secret? Not only would the lobe be able to be more aggressive to add power without effecting longevity, also the rollers would produce less friction so it takes less effort to spin the cam freeing up power. The sbc Vortec roller cams were controlled by a single spring with only just over .400" lift although those heads flow top out at .500" lift which left power on the table. I suspect they did that because they made enough power with the lower lift and the bean counters stepped in and had them go with the lower lift so springs would be cheaper more than longevity at mind, which is a coincidence that they run as long as they do because of the bean counters wanting to run the cheap lower tension springs. The same lifters were used in the LS series of engines with much more aggressive spring rates that are known to run hundreds of thousands of miles without fail. So if you're looking for longevity and efficiency a roller cam is the only way to go, unfortunately you would inadvertently make more power than with the stock replacement flat tappet cam if one would get off their wallet and suffered the one time charge to spring for the roller. If you plan on running the engine for hundreds of thousands of miles the cam will eventually pay you back with the better fuel economy that cam will give you over the flat tappet cam if you can keep off of the throttle for most of those miles. Derek
Six of one, half a dozen of the other. If you increase the velocity and CFM of the port, you don't need to have as radical of cam lobe. A simplistic exercise was to take the flow sheet and add up the CFM's at each lift point (before and after porting) to get a total CFM #. Regardless of the cam profile they go down the track much faster with flow increased throughout the mid lift. The cylinder would fill better whether you had a more intense cam profile or better airflow, it's kind of the same thing.
Ah yes, where to begin? You are notoriously famous for taking things personal/the wrong way, so let me try to explain: Rhetorically speaking (so it's not aimed at YOU), any knuckle dragger can turn a wrench and assemble parts using tools and parts engineered and manufactured by intelligent people who not only create things, but create ways for others less intellectually endowed to assemble said creations. Having said this, I myself have engineered, created, and assembled far more than what you have listed in this post. So if you want credentials, I have it in spades. But enough of the 'mine's this big, how big is yours' Neanderthal ego BS... To suggest using a stock cam (or any cam outside of radical) with low lift using high flowing, high lift heads is obviously a mismatch, and it doesn't take a genius to figure it out. So your abilities were not attacked, only the thinking behind your suggestion. I thought you knew better than this. Using a small cam to limit or choke off freer flowing heads is a poor design, even if the intent was to make it more streetable, leaving power on the table. A better method would be to design heads to match the cam, not use high flowing heads with a small cam. Velocity is killed this way, making the engine fight itself; so in this case you would have just the opposite of an overcammed engine with poor flowing heads, but with similar poor results (on different ends of the spectrum). The reason they probably did it this way was to use the same heads for different types (cammed) engines. They're not top secret. It is simply a roller version of the flat tappet specs, and I said I'd post them for anyone who asked/was interested. All I got was crickets, so I never wasted my time posting them. This particular cam grind isn't my design anyway, it's Federal Mogul's, so I can't take credit for it; I can, however, take credit for taking it a step further using the original engineering intent, with less emphasis on emissions control and more on extra power, so you probably wouldn't be able to use it with a catalytic converter without decreasing its lifespan. I do have other designs, though. Plus custom works on an individual basis. The rest of your post is pretty much what I've said also in previous posts/threads, and I concur. For some people, it takes more than simply 'getting off their wallets' as if everyone is sitting on thousands of dollars and is just too cheap to spend it--OR, maybe they don't have it or can see it better spent elsewhere on the car when the flat tappet cam is good enough? There's more than one possible scenario. My engine building suggestion is not what parts vendors want, so you won't hear much about it in advertisements and such, and usually the population goes along with it; hence, what you see today and in this and similar threads. I consider you a friend, Derek, and I have complete confidence in your engine building skills. You have some great ideas and are very helpful to others. You too are a valuable asset to the Buick community. Keep up the good work! (this IS directed at you) :grin: Gary
THIS. Is the premise behind my blueprinting stock-cammed engines suggestions, along with increasing velocity of stock low lift flowing heads using the stock low lift cam. This is how and why more power is added without affecting the powerband much, increasing the power output throughout the entire RPM band using stock parts. Engine longevity is retained, and power is increased. Gary
Efficiency is still going to increase yet with a more intense cam lobe, until you get to the point of over camming. Then you could tighten up the duration a bit or move the lobes around some. Longevity might not suffer. I guess one would have to compare the lobe lift/degree curve of this engine to others, maybe with a similar base circle. I think everyone realizes that the extra lift is there at times to keep things in contact, not just to take advantage of flow.
You could make a custom cam similar to the stock one with asymmetric lobes to milk maximum power out of it and still retain excellent longevity, but the power increase may not be enough to warrant it. I've shown where larger cams, while adding more power, won't last nearly as long and don't add all that much power to an already powerful design. If you're splitting hairs or like tinkering, then by all means. There's more than one way to skin a cat. Then there's the roller option, which solves most of the issues the flat tappet cam suffers from. I guess there's really no 'wrong' way to do it, as long as everything is matched up well, no matter what you want--whether it be stock or radical. Just understand there's a cost to all that extra power besides the parts and labor. As Derek has said in another post, some people enjoy tinkering and rebuilding every so often, so longevity isn't a big deal to them. For others' whose concern is to make their investment last as long as they can, or for those who wish to drive it every day, there is another option for them. Gary
Derek, have you documented the weight difference of the roller lifter versus the flat tappet in the same engine type?
I understand what you mean here but there is a part of this that was left out. High flow heads can also include small port versions where the port cross sectional area is stock or even decreased. The problem with the stock head is resistance to flow because of port core shift during casting where the port and valve seat are not aligned, too much material around the valve guide in the bowl where air pressure is very high as it is being redirected towards the valve opening and the not so good angle of that turn or port angle. If those areas are revised properly then the head will be high flow because of the increased velocity without making the port cross sectional area larger. Here is an extreme example of a high velocity Buick 350 head that included decreasing the port angle by raising both the roof and floor. The raise floor keeps the port volume relatively small and it helps with the flow around the short turn radius. Run something similar to this head with a Federal Mogul CS647 camshaft or a roller version and see what you get for power band width and magnitude. Paul
No sir, I have not. I don't have any roller lifters on the shelf except for some GM v6 roller lifters that are about 1/4" to 1/2" shorter than the v8 lifters. I can do a dry weight comparison of a GM hyd. flat tappet and the shorter factory GM v6 roller lifter if you would like? That's one of my pet projects I was considering to do is use the factory v6 roller lifters in a sbb 350 with the sbc dog bones and spider factory hardware. Of coarse a lifter girdle would need to be installed so there is a place for the spider to bolt to hold the dog bones in place. This has already been done in a non-roller block sbc so I figured with a bit of altering of the factory hardware why not in a sbb. Anyway I don't think that small of a weight difference on that side of the rocker makes as much difference than the loss of friction would make going from the metal to metal of a flat tappet to cam lobe to the roller wheel of a roller lifter on a roller cam lobe. With a solid roller cam the heavier weight could make a difference in an high RPM application, if so a rev kit should be installed that keeps the lifter in contact with the cam lobe so the spring pressure controls the valve more so than the lifter. Derek
Still don't believe these stack up issues can be correct. The push rods also would not fit correctly. If designed for near zero deck for the advertised compression then adding .050 to .060 more deck height to allow remachining at rebuilds then the as designed pushrods would not compress the lifter at all and in fact would be loose. When I had the block decked .055" and the heads just cleaned up at .015, I had to have the intake cut .030 AND shorter pushrods by .025". My new combo with more cut from the heads has the lifter preloaded to .085" so shorter pushrods should still be used. ( -.040" on order) I can't believe all these parts would need to be changed with non stock parts at rebuild time. Did they expect these engines were going to be rebuilt several times? I'm thinking since the stock OE as built engine went together fine (IE. pushrod length, intake fit) there was a mess up with rod length or the pistons were just too short. What I'm saying is I don't think they left .060" material on the block for future rebuilds to eventually achieve the advertised compression ratio. Every 350 I've seen with factory pistons were way down the hole. Doing the math on them showed they were no where near the advertised compression until zero decked. Being designed for and using .020" shim head gaskets, i don't think they planned for composition gaskets to be used. By the way the Sealed Power Hyper eutectic pistons in this engine have 1.85 compression height and still had to have the block cut .055" for near zero deck and actual 9.8 compression. The pistons were advertised as 10 to 1.
9.8-1, That's with the composite gaskets? You know the T/A large valves take up some room without the dish in the intake valve head. Also, you can leave them proud when machining for seats, taking up a bit more combustion chamber space.
9.8 was with the small valve heads. The new heads with big valves are 10.12. They have been cut so much that the pushrods are too long with them causing the lifter to be compressed to about .085" which is too much for my liking. Yes, composition (FelPro ) on both. Mart, Norwalk race make up date is Sat. Oct 3. You need to bring your car out and run it.
Steve, been limping around lately. Fractured right ankle, banged it just right on corner of floor jack swapping rear axles 4 weeks ago. Tough braking and flooring the peddles. Only easy, cautious driving. Did manage to run out to North Gratiot cruise yesterday. Quite a few Buicks out. Nice event! Significant others 61st Saturday too. She doesn't care for the Norwalk b-day present idea too much:laugh::laugh:
