I kinda hope your off Alittle on the race fuel in the 70 SP engine. I was going to go with the Crower in my SP engine as I felt the 310 isn't what I want for my convertible. But it also means swaping out 3.73s and a 2800 convertor for something abit more mpg friendly. If my estimates are correct I'm at about 9.5 compression with .030 over pistons and fel pro gaskets. Which is just over what Steve suggests for this cam.
I thought Steve has 9.7:1 compression with the Crower Level 3? If not then what about the Crower Level 4 with a set of steal shim head gaskets swapped in? Derek
I have 9.6. Andy, You won't have any trouble with a stock SP engines compression if you truly have around 9.5 I went from 14.15 to 13.77 from the stock SP cam to the level 3 so I think Garys est. is a little soft. As for cam wear and general engine wear, when ever power goes up life span goes down. Also performance cams are always a tradeoff by increasing RPM levels. When have you ever installed a cam and made more HP at lower RPM levels? Unless your combo was waaaaay off I bet thats never happened. Good discussion, we'll see what the bigger valves and level 4 cam can do soon.
No, I don't want to burn race fuel everywhere, that was ultimately why I sold the Tempest years ago, was fine when you could still get 97 octane ethanol free at the pump, but those days are long gone....again, I'm not going to race the car, so If your advising me to leave the intake alone I will, I've never played with a buick engine before, or even a small block for that matter other then my 07' Mustang gt which I dumped way tooo much money into and still never felt it was fast enough. I've built up a 396 in a 72' Camaro, and the 455 in the 70' Tempest so I feel like I'm starting from scratch here a bit. This is also my first automatic trans in a car I am playing with, so that adds another thing I need to learn about.
the "doc's dual plane intake mod" thread on here might be interesting and useful for ya . could be a decent alternative to get ya by ( $0 pretty much ) until ya need to step up to the SP3 .
If "docs dual plane mod" involves cutting out the divider don't do it, you'll just waste your manifold. It does not work on a 350 and I doubt it works on anything.
Its a sticky in the Nailhead section, it doesn't involve removing the center divider only the front and rear dividers to replicate an aftermarket intake. The mod looks like to me that it would help get more air in? I wouldn't waste my time doing the mod on a stock sbb intake though when I have a choice of 2 different aftermarket intakes that are already like that, I would rather waste my time porting the new aluminum intake. Derek
Hey no one is perfect, and I'm certainly no exception to the rule! I was simply going off the compression test the OP gave for his engine concerning his stock engine, and the IVC points are 71*-75* depending on the grind, so putting a 66* cam in there would bump the DCR considerably beyond the 7.75:1 his stock engine already has. You could use the composite gasket instead of the steel one and may be ok with it, as long as your SCR remains between 9.5 and 9.75 or so for the Crower level 3. Polishing the combustion chamber will permit higher compression on the same octane, up to maybe around 8:1 DCR, but you're pushing it with an open chamber design. The Buick 350 has smaller chambers, so you can get away with more than you would with a wider bore design, but exactly how far you can push it may depend on a few factors outside of your control (fuel quality inconsistencies, etc.), so best to play it safe. Gary
It's too bad we have to port a brand new single plane intake to have it perform as it should. Per the other post it slowed the car down possibly because of the necked down ports to match any head. I just reviewed the nailhead post for doc's mods and can see where that would help on that intake. It looks very small and the increased volume should help them out. Makes our intakes look like a tunnel ram!
That sounds about right Steve, considering the DCR would have been much lower with the stock cam unless you changed things other than cam...which also means it's not just the cam that made up the difference, it was DCR plus other things. What surprises me is the OP's engine seems spot-on with DCR from the factory, where other 350's mentioned here on the forums are waaaay off. When comparing similar DCRs and other mods being the same, the two cams aren't that far from each other....according to the math. But who knows? Maybe it's off more than I think. Proof is in the pudding eh? Power CAN go up without sacrificing longevity, as I've mentioned elsewhere. Gary
For those of you who are even semi-paying attention, what this also means is the stock cam is capable of turning high 13's in the 1/4, possibly better with the correct massaging/blueprinting techniques. All while getting over 20 MPG and lasting you 200,000+ miles. Many stockers, even production engines with no extra work (that I suggested) done to increase longevity have lasted 300,000+ miles with proper maintenance. Let that sink in for a minute. I'll trade 250,000 miles for 15 hp, and this is on a fresh engine. Just how much more power will that performance cam have over the stock cam after you put 50,000 miles on it? How much more lift over stock does it have after the lobes are all rounded off? The stock cam seems pretty big at that point. There is NO comparison in my eyes. You want to go slightly faster for a short period of time, go right on ahead. The parts vendors will be happy. The real power lies in the other areas of airflow, i.e., heads, intake, and (small primary) headers. Obviously we're talking mild street engines here. All out racing applications give less than a rat's ass about longevity. Gary
For your consideration Some work I did with the 350 a while back http://www.v8buick.com/showthread.p...fo-and-dyno-results&highlight=tsp+level+1+350 I agree with much of the advice given here.. I agree that the current generation of many companies fast ramp cams are not the way to go with any Buick, especially the 350. Noisy, short lived cams with questionable power gains is most likely what your going to see. I agree that you should not open the engine up now. Nothing you can bolt on, or in that engine is going to "light your fire" to borrow an old advertising line. The 350 is an entirely different creature that the 455, about the only thing it has in common with it's big brother is a front mounted distributor/external oil pump. It does not respond as well to bolt on mods and "super-tuning"... like the 455 does. Don't get me wrong, I am not knocking the 350, just laying out the facts here. It is a lot harder to make power with the 350, than with the Big block. This fact would sway me toward simply keeping your current engine stock, maximizing the tune, and then open it up down the road, when it really needs it, or when real, honest to God, cylinder heads are available for it. And you see the blueprint laid out in that thread on how to build it, and what to expect. I don't at all agree that installing a stock replacement cam is the only thing you can do. Consider my real world results with that Level 1 350 Build. That motor drives wonderfully, has just enough cam to have a little exhaust music, but not to hurt low speed driveablity. Low lift, low valve spring pressure requirements make it just as durable as any replacement cam will ever be. The next generation of that motor is sitting on the floor in the shop right now, viturally the same build, but with a roller cam. We will test the SP-3 on that engine, vs a good ported stock intake. One thing I should point out is this: I see alot of talk about useable power. I would put it out there that the engine with the best useable power, in a 3.08 to 3.42 geared 70 GS 350 type car, is the one that has a torque peak of around 3800 rpm, with a flat torque curve, and power producing capability to the 5500 rpm range. Think about it.. go out and do some agressive driving with your GS. Even in stock trim, 2800 rpm goes by pretty quick in first gear at WOT, and the engine never returns to anywhere near that rpm again, in a typical "power run". That being said, I agree that careful attention has to be paid, not to turn our 350 into an ill tempered, high rpm motor, that's not the motor that most guys really want. And lastly, it's always about combination. A combination of engine and drivetrain parts, will help you achieve the goals your wanting. It's not about one part, or a couple of bolts ons. Good luck with the project. JW
With all the opinions and facts laid out in this thread my thought is there is a need for a new cam grinds. The ones available are old design. Outdated tech. A few people have gone to custom grinds on lower compression engines with big valves and have gone past the 400 HP mark. Which seems is a hard task to do. These engines can't be limited to just 350 HP unless its an all out race engine. The question is what's missing or holding it back.
I agree with most of what Jim says and that power range is spot on with my combo. I don't agree with the comparison to the 455. The 350 is almost a 7/8 scale 455 in layout and I've found them to respond much alike. The big difference is the bore /stroke relationship, 350 being square and the 455 with it's much larger bore. Maybe that's why they do have their own quirks. The Crower cams seem to be very gentle on the ramps and I will be pulling my level 3 tomorrow. Will post pics of the lobe to see how they are wearing. Crower cams are the most advanced applications for the 350 and do not seem to be Chevy lobes on a Buick core as other offerings are.
The Buick 350 piston accelerates and reaches maximum velocity at 75 degrees ATDC. The object is to transfer as much of that kinetic energy to the incoming air mixture as possible. So it is important as to what gets done in that window of crank rotation. Gary talked about asymmetric lobes where opening time is shorter and quicker than closing time. Increasing valve lift also increases opening ramp rate but then there is the conversation about shorter valve train life span. IMO the real solution is roller cams. I know that the first thing that comes up is the increased cost and then there is the counter answer of "What is saved the first time a lobe goes flat and hard steel particles go through out the engine". However the answer is still the same. The roller cam opens up a whole new set of modern tech profiles without sacrificing long term service.
The only other down side to roller cam beside cost is the heavier lifter needing more spring pressure to control. Also more weight/leverage to support by the already weak lifter bores but the roller helps so that's probably a wash.
You can make larger than stock cams using asymmetric design, which will make them gentler on the valvetrain, as long as you didn't go crazy on the lift. I already have grinds pending on additional information from the users (board members) who have requested them. Asymmetric design is more effective with smaller cams, as there is more room to work with than larger cams that have a lot of duration. It's all about duration and placement of lobe centers in relation to each other. The lift side of the lobe will open the valve faster while the closing side closes it slower, allowing it to stay open longer within the desired lift spectrum without having to add excessive lift (and therefore more camwear). The gentler closing slope also creates an easier life for the head seats, and requires less valve spring pressures to remain stable. The lobe center @.006 is in a slightly retarded position, while the center @.050 is advanced. This permits you to run higher compression than you could with a symmetric lobe, and is why the static compression on a stock cam needs to be around 10.21:1 for ideal dynamic compression. There's several advantages to asymmetric lobes, which is why the stock cam does so well despite it being so small. The Crower level 3 and TA 212-350 both have the same IVC points and only need about 9.81:1 compression to achieve the same DCR as the stock cam at 10.21:1. The smaller the cam, the longer it will last; however, you CAN make performance cams last longer by adding asymmetry to the lobe design. It's always a tradeoff, but to me, the small gains of performance flat tappet cams over the stock cam just isn't worth castrating the camshaft's lifespan. As Paul mentioned, ultimately the way to go is roller cam if you can afford it. Gary
Re: For your consideration With all due respect... All camshafts last forever in an engine that won't be driven much. For every day driving, piling 10's of thousands of miles on them over the years, it WILL wear out faster. It is a mathematical and physical certainty. This is pretty much the main thing that's 'wrong' with performance flat tappet cams. Sure they're great while they last, but in a few years (if you only drive it occasionally, much sooner if you drive it every day) they will begin to get tired, won't idle properly, develop a dead skip, etc. (many may not even notice because of the already rough idle the cam gave, though they will notice the engine getting tired) from lobes that are biting the dust, at which point a similar engine with the same miles on it using a stock cam is just getting good and broken in. We need to make a thread here listing the people who have certain cams and how many miles they have on them, when they had to replace them, when the engine became tired etc. "Mine lasted 12 years and is still going strong!" you might hear, but then ask them how often they drive it and it turns out to be only a few hundred or a couple thousand miles total. So far, we know that a TA 510 cam can last as long as 5000 miles (that's not even two oil changes @3000 mile intervals), maybe others have had better luck? Others wipe lobes right from the git-go trying to break it in, and these are not super hot cams either... I know special procedures have to be observed while breaking in a cam, and even then it's fingers and toes crossed in hopes a lobe doesn't wipe. If it does, not only are you replacing the camshaft, but rebuilding the engine again as well from all the metal fragments plugging oil journals and scoring bearings/rod/crank surfaces... Racers won't expect a long life out of their engine/camshaft anyway, but it would be nice to know how many hundreds of miles they can put on it before the cam is a smooth iron pole. Roller cam is certainly the way to go here, but even then people want to go nuts with lift and profiles simply because the cam won't wipe immediately after having done so, but roller cams and lifters do crap out after a while if the profile/lift is too great. Ticking time bombs I like to call them. Creating a (relatively) mild roller cam is the ultimate in camshaft longevity, obviously, with regular preventive maintenance lifter replacement after so many miles. I recall a conversation similar to this one we had once before some time back concerning roller lifter longevity and when it is best to replace them. As far as flat tappet goes, my money's on the Federal Mogul CS647. Gary
I drove a Erson cam, a 113 from Poston for 6years daily has my high school.ride ran the poor car more than most anybody ive got slips up into the 200's, drove it at 75mph at 3200rpm to the GS Nats in Ohio 12.5hr one way. Drove it to Reynolds GA 8hr one way and it ran 12.40s at all venues over that span, after approximately 40kmiles it lost oil psi due to some chewed up cam bearings, cam I sold to friend who put it back in service. So imo your theory on performance cam longevity isnt warranted. Hell we got 10yrs and close to 10kmile on.my dads 107 499lift window rattler still pulls like mad and idles rock steady at 1100rpm And as to people wiping cams at breakin imo almost 99% of the time has to do with some incorrect valvetrain issue, or to much spring psi ie inner spring in place on duals. A lobe just eating itself had help from something
Well this has all been more than informative. I have been doing tons of research on this and other forums since I got the car, and I have determined that I am not going to get the pure pulling stomp and throw you into the seat power I am looking for out of the 350. So what I have here is a very nice all original numbers matching 120000 original mile 1970 GS. I am going to leave it that way, the exhaust needs to get done so it will. Beyond that, I am going to finish off the interior, track down some new trim pieces to replace some cracked ones, and this car will be a very nice, well mannered driver that even the wife can drive. As I stated earlier, I've never played with a Buick before, and the 455 seems to be the way to go if your going to do it. I will not do that to this car, if it was a regular old skylark yes, but being what it is, I feel it would be a shame to cut it up and modify it from original. I'll finish this one off, and find another to turn into a beast.
