Anyone happen to know what they are? Lift, duration, LSA, all that stuff. Yes, I know they are in the shop manual for the '70 Skylark, but I really don't want to buy a manual for a car I don't have for one piece of info. I can't find the specs anywhere on the net either, which is weird. My guess is it would be in the low to mid .4xx for lift and mid to low 200s for duration.
So, I'm often confused on which rocker ratio Buick engines use(1.55 or 1.60), based on the stock replacement CS 647 cam from Sealed Power, lift is more in the .390 to .405 range on the intake side. Intake duration is 189.
I had read that it had a lot of duration . Like 304 on exhaust . I think Gary may have accurate specs. 398 lift I think. 70 was different then other years. 1.55 is the spec I would use.
there is only 1 cam listed in the parts book for a 1970 350 engine. The SP cam is the same as every 350 used.
I do find this interesting compared to Pontiacs, the lack of easily located specs for the Buick 350 cams. For Pontiacs if I want camshaft specs for the factory cams I can go to half a dozen websites and get them. Along with a bunch of aftermarket cams for comparison: http://www.pontiacpower.org/PontiacCams.htm http://www.classicalpontiac.com/restoration/cams.html With that said, I do think Pontiac had more variation among its factory cams from mild to much more performance focused (Ram Air II/IV grinds).
.381 intake lift .389 exhaust lift Any other specs I don't remember, I might be off on the lift specs too, LOL
IIRC, there wasn't a specific "GS" cam. They may have tweaked some specs. thru the years, but it was probably for emission compliance, not power.
Yes just one 350 camshaft. 1970 GS 350 engine made 315 advertised horsepower with more compression, dual exhaust and functional cold ram air system over single exhaust low compression non ram air skylark engines.
I have a 1973 parts book. Shows only 1 cam. If you find another PN specific to a 1970 315hp engine let us know.
To the best of my knowledge, there are three possible OEM replica cam replacement choices available: one from Federal Mogul listed as cs647, and two from Melling listed as sbc-5 and sbc-11. There used to be another one made by Federal Mogul, but as far as I know, it's discontinued. I can't remember the part number on it. The Melling sbc-5 is similar to the Federal Mogul cs647 as it is listed as the "GS" cam for use with '68-'74 engines, and the smaller sbc-11 cam for use with '75+ engines, though they are interchangeable. I'll spare you guys all the boring details of each cam, as I've listed them elsewhere on this website numerous times before. As far as different power ratings (and has been previously mentioned), other aspects of the engine can affect the power output greatly. Take any cam for example, mate it to a small 2 barrel, a restrictive single exhaust, untouched heads, and low compression and you'll end up with weaksauce power any way you slice it, when compared to other components that would allow the engine to perform no matter which cam was used. The OEM replica cams are good choices for simple replacement and have excellent reliability, longevity, and versatility. Everything has its uses as well as its strengths and weaknesses. Nothing wrong with any of it if it's what you want to use.
So, if I took a 155hp 2 barrel 8:1 motor, and put dual exhaust, high compression, and a quadrajet, with nothing else, it would be comparable to the SP 350? I doubt the ram air added that much hp, as if I remember correctly, they dyno'd the engine's themselves on a stand, with no accessories or air cleaners. Unless they installed the air cleaner and aimed a fan at them at WOT. It might just be that "oh this make did so and so with their motors" mindset I have, but I find it hard to believe Buick were too lazy to design a better cam and just slapped the same cam in everything. But if it's true, it's true I suppose.
The power figures you see that are less than 200 hp are net figures, which means they considered all accessories installed and operating (including the AC), and measured it at the rear of the transmission. This dropped the power figures 'on paper' substantially. Then the use of lower compression and more restrictive exhausts (starting in '75, the pellet style catalytic converters were introduced) drove the final nail in the coffin in terms of performance. The '315 hp 410 tq' numbers were sexed up for marketing purposes, which every automotive maker did. The ram air did not increase the engine's power that much, and even hindered it at higher speeds due to the ram air inlet's location on the hood. Dyno numbers for a factory assembled, stock '70 engine that was supposed to produce those numbers in actuality made 385 ft. lbs. and 270 hp. By comparison, Chevy's '300 hp' 350 engine produced about that much too (give or take a few numbers difference), so it wasn't just Buick doing this. Compression ratios weren't exact, and were off by as much as half a point to three-quarters of a point. The cylinders varied in compression as well, showing some to have more than others. This is normal on all engines, particularly assembly line engines. Chevy's camshafts weren't much larger (if any) than this cs647 cam, which compares to the '325 hp' 327 camshaft. Older Buick 350 camshafts won't have a super smooth idle when idled down, hinting that there might be more to these cams than the numbers on paper suggest. We've all been programmed to believe that anything less than .500 lift and 230 duration is 'small'. Buick 350 head flow peaks out between .350-.400 lift on intake and plateau's off between .300-.500 on exhaust. Better power improvements can be found by increasing the lobe intensities rather than increasing raw lift, though doing the latter tends to improve the former on an incidental standpoint, though by doing this you will decrease the lifespan of your camshaft--if that matters to you. (flat tappet cam designs) The OEM cams are asymmetric in design, having faster opening and slower closing ramp profiles, showing a retarded setting @.006 and an advanced setting @.050, so they're much more complex than a typical symmetric ground lobe, which uses larger sizes to cover the key areas that the valve events need to be in when considering a 'performance' engine, as opposed to a more precise timing event (think of it as using a shotgun vs a rifle to hit a moving target). Other aspects of camshaft design taken into consideration were emissions, longevity, and versatility, rather than just simply focusing on raw power output, which would have been the real 'lazy way out' approach in dealing with this issue. Try not to get too caught up in the output numbers. They can be misleading on how an engine will perform in the real world. I hope this helps. There's more material on this subject scattered across this website, and since the search feature has been improved, you may have decent luck at finding some of it.
That's a lot of info to swallow, but I get ya. I do wonder how this SP 350 will perform compared to my other 350 I had with the 8:1 and the comp 268. I plan on putting in a TA 284 or the 290 cam, trying my hand at lapping the valves, the valve springs, lifters, double roller timing set, hone, re ring, re bearing, re gasket, oil pump mods, etc. Should be pretty peppy I'd say. It's been apart before but hasn't been bored over. It may have had a previous re-ring job, as the rods are numbered, it has clevite bearings, and Victor Reinz headgaskets.
