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Old 12-12-2012, 11:34 AM
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Quote:
Originally Posted by ChevroletSS View Post
Hey guys I was wondering if you all could explain different types of camshafts for me and others to reference. Like whats best for certain applications. Different sizes cams, different lifts, LSA, Durations. Why we would use one cam over another and benefits.
All of us rodders began clueless. I remember being clueless, so I'll wade in with a little something basic for you.

Currently, there are 4 types of camshafts.
1. Flat tappet mechanical. Simplest and cheapest. Requires periodic adjusting of the valve lash, like maybe twice a year. No restriction on achieving high rpm's, will rev until you run over the crank if you use enough valve spring and lightweight valves, retainers. Good choice for budget smaller cubic inch motor that needs to rev to make power. The idea of this design is for the cam lobe to lift and spin the lifter in its bore as the cam rotates. Visualize the bottom of your shoe against the pavement as you walk. The sole of your shoe keeps you upright against the weight of your body while "rolling" the sole of your shoe against the pavement. The fact that shoe soles wear out tells you that there is some friction in this action. Same with flat tappet lifters. Everything must be exactly right for this design to work properly and most problems will surface early on. Improper lubrication, using stiff springs for break-in and interference of parts (valve contacting piston, stacking solid of valve spring, retainer contacting valve guide boss or seal, binding of stud against rocker) can be blamed most frequently. Here is a tutorial to explain the things that can go wrong with flat tappet installations.....
http://www.crankshaftcoalition.com/w...ips_and_tricks
Mechanical (solid) lifters can be purchased with small holes in the crown that are EDM machined into the lifters during manufacture. These holes supply oil directly to the lobe/crown interface, helping to prevent failure.
2. Flat tappet hydraulic. Cheap. Lifters adjust the lash automatically, no periodic adjustment needed. Rev-limited as compared to mechanical cams, although design improvements have made them the standard of the industry.
3. Roller tappet hydraulic. More expensive. Less problem-prone than flat tappets in the area of contact between the lifter and the cam lobe. Rev-limited due to the weight of the lifter, usually about 6200 rpm's in a small block Chevy, although there are rev kits that allow you to install additional springs in the lifter valley for more revs. Considered a "girly" cam by some.
4. Roller mechanical. Used on builds where max power and max revs are the ultimate goal. Expensive. Periodic adjustment required. Mechanical roller tappets are now offered with direct pressurized oiling to the needle bearings to help prevent failure from lube starvation.

One of you fellows might want to start a wiki article under your screen name, expanding on what I have said here, so that newbies can begin to get an idea of what works with what.
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