MATCHING CYLINDER HEADS TO CAMSHAFT
Most cylinder head companies are happy to give their flow figures out. And, armed with that information, you can call any of the major cam grinders and tell them what heads you've got, along with the rest of your package, and let them make the best selection for you. The days of asking your buddy at the local grudge night are long gone. Unless he's got access to a Spintron and dyno, his input is probably useless, (sorry guys, but that's the truth). If you're willing to spend the money on a good set of cylinder heads to build your engine right, then you should also be willing to step up to a good hydraulic roller cam and make the best power you can.
FLAT VS. ROLLER TAPPET TEST
We know someone is going to ask for it, so now we'll explain why it really doesn't make any sense. We're talking about a dyno test between a flat-tappet cam and a hydraulic roller cam with the same specs. The reason it wouldn't work is because even if the numbers @ 0.050 were equal; the cams can never be the same. Roller lobes can be designed to open the valves with much more "area under the curve". That means that as the valve approaches max lift, a roller tappet can hold it open longer than a flat tappet. A roller vs. flat tappet test could never be equal. If we were to grind a roller lobe to EXACTLY match the profile of a flat-tappet lobe the results would still show the roller ahead, albeit slightly, simply as a result of less friction. But, there'd never be a reason for that type of lobe, or test, because it'd not be taking advantage of everything a roller tappet has to offer. However, we've done a few tests that closely mimic this idea and found interesting results. Certain flat tappet cams might be capable of more low-end power due to their slightly more aggressive initial opening rates. But their advantage quickly goes away as frictional losses start to take over compared to roller tappets and the top-end power increases of the roller tappets will far outweigh the marginal low-end advantage.
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ISKENDERIAN RACING CAMS (ISKY)
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Lunati Cams A division of Holley Performance Products
4770 Lamar Ave