The advertised 1970 Buick GS Stage 1 camshaft duration specs are 316 Intake and 340 exhaust with 90 degrees overlap both with .490 inch lift. As we all know, Denny Manner put out these specs, so anyone running NHRA stock eliminator back in the day, could run a bigger camshaft and be very competitive in drag racing. If these duration specs were converter into .050 duration specs what would they be.
The .050 specs could be almost anywhere, depending on how gentle or intense you wanted the lobe profiles, and where you wanted your powerband to be focused. TA's rendition of the Stage 1 cam shows 210* intake and 224* exhaust @.050 with a 113* LSA. The OEM replacement (non-stage) cams from Federal Mogul show 194* intake and 225* exhaust @.050. With the 'advertised' durations you listed, .050 could be placed much, much higher than these (well in excess of 240*+) and still have a good ramp profile with tighter springs. If you gave 60* lobe intensity to the cam specs, a 316/340 cam would look like 256/280 @.050. That's f'in NUTS.
I would have to find my notes but when I checked mine I want to say it was 209/224 on a 115 LSA. I think the "Pure Stock" will accept 210/230 and any LSA.
An old Wolverine/Blue Racer catalog showed this grind at 207/225 . They advertised that their OEM replacement cams were made from original GM blueprints/specs.
From memory, I believe it was 115. I will check tonight when I get home Sent from my XT1254 using Tapatalk
The Wolverine Blue racer catalog lists the Stage 1 cam: 208-227 duration @ .050 lift, 316-340 advertised duration, centerlines 112-118 hence 115 centerline with valve lift at .417-.453. The originals that I have checked are: 208-227 duration @.050, 300-320 advertised duration (I think this was at .006 lift), centerlines 109-120 with valve lift at .405-.443. Not very large when compared to some of the other brands performance cams.
Thank you for sharing this. For reference, here's FM's OEM replacement 'non-stage' rendition: This cam is asymmetric in lobe design, with opening ramp profile occurring quicker and closing ramp profile occurring slower (relative to opening). These specs may have some scratching their heads, as it does not follow familiar and intuitive symmetric lobe patterns. (hint: put in the valve timing events into a calculator for both .006 and .050 and see what's going on) Notice it has a 91* intake valve closing point (@.006). The Wolverine specs you gave above show a 90* intake valve closing, assuming a symmetric pattern. The original shows a 79* closing point, assuming symmetric patterns (better fuel was available back then), but may have been .006 instead of seat, as you suggested--in which case it would have been 87* @.000. Might make a few people reconsider what the big block needs for DCR with no quench platform, and may explain why detonation is present at higher RPMs when it runs fine at lower RPMs. There's a lot of dynamic activities going on inside that combustion chamber, for sure.
