Posted by forty40 on August 28, 2013 at 18:54:38 from (74.77.12.246):
In Reply to: cam regrind posted by farmallhpuller on August 27, 2013 at 07:10:33:
Large diameter lifters do not mean a builder can arbitrarily put in a radical profile with a steep ramp; materials, heat treating, and, matching surface hardness are critical. For flat tappet cams using .875 or .904 lifters with moderate profiles we’re running valve springs with 500 lb over the nose, $360/set, steel core cam, $750, and PPPC steel billet lifters w/casidium coating and an EDM oil hole @ $900/set. So, yes, a larger lifter certainly allows a much more radical cam profile, but it isn’t cheap. Camshaft profile is an interesting topic but requires evaluation of at least 11 key factors in engine performance. Piston crown, chamber shape, chamber volume (the whole upper configuration and comp ratio), intake runner volume, runner profile (desired flow velocity), rocker ratio, max valve lift, piston speed, lifter dia, top engine RPM, and desired max torque RPM. My experience is primarily circle track engines but I’m guessing the power curve for pulling with a naturally aspirated lower RPM engine, isn’t that much different. Power on the low end (torque) with a steady increase in HP up to max RPM. I’ve only begun my first two tractor engines, so we’ll find out if racing actually translates or I’m just full of it. On our used but not abused parts shelf are cams from Comp, Crower, Isky, and Bullet. All worked well when matched to the engine configuration and RPM range being used. One of the bigger mistakes I see is people just copying something they have seen or heard about without thinking it through and optimizing all factors, usually ending up with a bad power curve. The other issue I see is guys are not taking the time to degree in the cam so the engine can operate in the productive part of the power band. Usually cams are installed too late, too high int centerline deg so the engine bogs down low and they think they have a bad cam. A street stocker dropped off a motor last month, sure enough, the cam was in at 102 and should have been 98 or 99. I’ve only had one mfg with a poor cam which was actually bad workmanship, steel core w/roller lobe blanks, ground to a flat tappet profile, but neglected to re-heat treat (nitride). You can guess, about a 100 laps and a Schubek lifter broke through, everthing went to pieces. (literally) So, all that BS to say this, when I hear people downgrade a builders heads, cam, or part selection, there’s often a lot more to the picture that made things not work out.
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Today's Featured Article - Hydraulic Basics - Part 2 - by Curtis Von Fange. In the last entry to this series we gave a brief overview of hydraulic system theory, its basic components and how it works. Now lets take a look at some general maintenance tips that will keep our system operating to its fullest potential. The two biggest enemies to a hydraulic system are dirt and water. Dirt can score the insides of cylinders, spool valves and pumps. Wate
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