what are the cam specs on the stock buick 350 1973 2bbl?

300sbb_overkill · Jan 26, 2015

Gary Farmer said: ↑

With smaller cams (lower lifts and shorter durations), causing the lift side of the lobe to be angled a bit steeper creates a faster lift/ramp profile, which causes the valve to open faster, while on the closing end of the lobe the distance between lifts is increased so that the valve closes slower. This permits the valve to stay open longer with shorter lifts and durations, maximizing the time spent open within the desired window of operation. It also creates a gentler closing for the valve seats. The valvetrain doesn't need as much spring pressure to operate and maintain stability within the operating range of the camshaft. This creates a gentler environment for the entire valvetrain which results in less wear over longer periods of time.

This also creates a wider window for dynamic airflow to take advantage of gas movement past partially open valves dependent on engine RPM and airflow restriction/demand. In other words, the more the engine is restricted, the lower the RPM powerband and less power; while the opposite is true for a freer flowing--albeit higher velocity--environment.

This is of course true for all camshafts, but is more prominent with asymmetric lobe designs with gentler ramp profiles.

The only real 'bad' aspect about it is that aftermarket parts vendors sell less parts over time, which hurts profits. Another potentially 'negative' effect is the engine won't make as much power as larger cams take better advantage of higher flowing heads. For a street driven car driven daily though, this is about as good as it gets when everything is considered using basically stock components that have been massaged for optimum performance.

As camshafts get larger, the lobes tend to become more symmetrical, since the need for asymmetric lobe design wanes, because there's simply less time and distance between events for it to really matter. You could still gain from asymmetric lobe design with larger cams if the camshaft radius was increased.

Gary
Click to expand...

Great stuff Gary, thanks for taking the time to write all of this.

Now for a question with one of the gentle on the lobe cams, if we put a set of well ported heads on an engine with lets use your favorite in this "if engine" the Federal Mogul one and increase the rocker ratio to MAKE that little cam give more lift to take advantage of the porting, will it break above the 398 HP barrier?

Lets say we increase the rocker arm ratio to 1.9:1 will this make one of these cams a performer? Probably would need slightly heavier spring pressures for that massive(compared to stock) .462" int. and .480" ex. lift. Can you do an dyno simulation with the F/M cam with 1.9:1 rockers with heads that flow lets say 260 CFM @ .550" on the intake and like 174 CFM ex. max?

Very interesting stuff, makes me wonder what the limits are for the factory grind. Thanks in advance Gary, great job.

Derek

gsgtx · Jan 26, 2015

Gary,thank you for the post.

TheSilverBuick · Jan 26, 2015

Excellent information in this thread! Especially how the OEM does things, especially on "advertised" numbers and the asymmetrical information.

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what are the cam specs on the stock buick 350 1973 2bbl?

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