Things to look for when building a performance head. First off start out with figuring out your CFM or cubic feet per minute. From there decide if youre going to port and polish your head personally polishing is a must to increase air flow. Porting is by application purpose. Next using a flow bench find where you get the most CFM. Its not always that the max valve lift the springs and valve stem allow. The reason is after opening so far you actually lose the venturi effect and start losing velocity of the air coming into the cylinder. Now that is for future reference. Now theres more ways to increase air flow such as radius cut seats, porting, and larger valves. Then theres deciding what application you are using this head for. Do you want lots of torque of the bottom therefore having a smaller overlap in general or do you want a lot of overlap for top end for say flat track racing or something in the middle. Now is where you decide valve lift lift durations and other aspects of the cam. Then theres deciding what valve sprigs to use. Thins can be tricky because you need strong enough springs to lift the valves to prevent floating a valve yet you dont want it so stiff its hard to open the valves and basically flatten your cam then you have to make sure the harmonics of everything doesnt cause the valves to break. You have the option of running all sorts of springs to accomplish this some of those options include honeycomb springs progressive springs single rate standard springs and dual spring options and more. you will also have to consider what kind of valves to use as well. For basics however the less reciprocating and rotating mass in an engine reduces friction and allows higher rpms and throttle response. From there you have to figure out what valve clearances you need to run the cam grinding company should tell you what they recommend and go from there. Now that you have your valve lift figured out from there you need to check piston to valve clearance so that you dont have engine failure of obvious reasons. Now it cant just be o well it dont touch its good. You have to make sure by knowing what the materials expand to when at operating temperature that they still wont hit the piston. Theres a few different ways to do this so Ill leave that for another day. Once youve checked your piston to valve clearance and either installed the new piston or ground down the original one its time to assemble. If you dont have timing marks youll need to know how to degree cams and time it from there. Now dont forget all this head work is pointless if built for the wrong application or your suspension is setup wrong or your timing is off. Remember if you cant get the power to the ground and making it usable theres no point in having it.
Posted on: Wed, 28 May 2014 09:50:24 +0000
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