Max lift occurs when the piston is more than halfway down the cylinder. It does NOT cause piston/valve interference. Duration causes P/V interference during the overlap period when both valves are open. In a BBC the exhaust will clear near anything since its so far away from the piston crown. A tight lobe SEPARATION is just what a jet needs, it gives a narrow, peakier power band, but causes more interference problems. A jet only needs max power at max RPM of the pump capability (what the engine can actually turn it to). A BBC with the typical flat top piston with no intake notch, un milled heads, un milled deck will sometimes (50/50 chance, but will sometimes self clearance with a small crescent where the intake valve touches) clear the piston with a Comp Cams 292 hydraulic (great for Bassett exhaust, but too big for logs). A safer alternative and one that will always work is the Comp 288 or XE284 for Bassetts, and the XE 268 for log exhausts. Comp cams have typically faster ramp rates than other cams, this makes more power, but will cause a light valvetrain noise(ticking that you can't seem to get rid of, so don't try.) The best jet boat Comp solid roller is the 288AR, or for 496 builds if you want a bit more, the Comp XR286R. Any cam that says"easy on parts", or comes from a small or older "traditional" cam company usually means its ramp rate is slow, and may not make much more, or any more power than a fast ramp rate hydraulic cam(I.E. Comp Magnum or especially the Extreme energy series cams.) I have a cam analyzer and have analyzed thousands of cams in the last 25+ years. We charge $18.50 for this service, and can save you much cash and time. Ramp rate is extremely important to power production, and all cam companies don't have the latest computer design or manufacturing equipment. You can't tell ramp rate, or quality by looking at a cam. It is a safe bet that buying the same cam from the same company that your dad/uncle/neighbor used "back in the day" will be a disappointment, BUT if you never compare it to something modern, you'll probably be satisfied. At least until you race somebody with a newer setup..... Class dismissed. TIMINATOR
