Frank. While those multi-duration cams have been around for awhile in some of the high end racing venues, they are now being offered as a ‘shelf’ item for the masses. The horsepower gains are not much though and a typical gain is about 3HP on your average hopped up street engine. Those magazine guys getting free cams for testing will make a big deal out of the smallest of power gains. Considering how sloppy some of the cam grinders are in matching the lobes from cylinder to cylinder, multi-duration cams are an easy out for explaining away cam grinding variances.
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I’m learning that what works for the scrub engines isn’t necessarily what’s best for the Y engines or for that matter, doesn’t work for some of the other main stream engines either. The various engine designs all have their little nuances that makes each one unique. The intake runner lengths on the Y are much more equal in length than a majority of other engine designs which negates the multi-duration camshaft making any difference in this case. Camshaft lobe centerline reduction is also another area that the scrub engines favor while the Y tends to likes a wider lobe centerline angle.
Ted, Learned the second paragraph long ago with Pontiac Aftermarket Speed Equipment. The stuff was absolute junk on a Pontiac. It was developed For the SBc and just scaled up. Even most Isky stuff didn't work.
I remember you telling me the cam issues before and I'd be hard pressed to Argue. Most of the time when I check one the lift is about right but the timing events are all over the place. I usually attributed that to my methods of checking but the a pattern begins to emerge. Cheap cams are cheap for a reason.
I was thinking about the dual pattern cam to accommodate the difference in cylinder filling (if any) from what John said. The one side being separated by 180 deg's and the other 360. Be a very expensive deal to find out on a dyno.
Frank/RebopBristol, In ( by Elkhart)
