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| The Honda K series engine uses a lash adjuster screw. Although it is a little heavier than more typical shim adjustment, it is much more simple to adjust with a wrench, screwdriver and feeler gauge! |
During the cam install process an interesting point was brought up in relation to valvetrain components used with performance cam upgrades. For an unknown reason the myth that double valve springs need to be used in conjunction with performance cam upgrades has been the norm for many years. APD in it’s usual fashion chose to look at the science behind this in the quest for optimal performance from their Honda K Series motor. Let’s look at why APD after discussions with Martin Tagliavini of Supertech Performance chose their “Beehive” single spring set up over the expected dual spring choice:
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| The new Blueprint Racing cams were coated in assembly lube prior to installation. This help ensure lubrication during the critical break in period which takes about 20 minutes. |
1) Resonant Natural Frequency (harmonics): a traditional cylindrical spring has several defined natural frequencies. In a Dual spring, Outer and Inner spring are designed to have different natural frequencies between each other so they can dampen or counter each other, but the Beehive spring has a variable natural frequency that is continually changing as the valve progresses through the opening event. So it is a big advantage over a regular single spring and does not need an Inner spring to counteract an eventual spring surge and can have a better control over the valvetrain.
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| Interestingly Blueprint Racing modifies the cam phasing spring to limit the amount of advance/retard the mechanism has from 50 degrees to 35. They feel that this gives a margin of safety preventing valve clash if the valves go into float. This pin is inserted into the oil chamber of the sprocket and prevents about 15 degrees of movement. |
2) Spring Rate: The cylindrical spring with evenly spaced coils has a constant defined rate. The beehive spring, on the other side has a variable rate that is also continually changing as the valve progresses through the opening event, becoming stiffer as it compresses. In this way you can have a spring with a lower seat pressure with the same opening pressure.
3) Spring/Retainer alternative mass: Because the beehive spring is smaller at the top, it has a lower alternative mass. This allows the use of a smaller retainer adding to the mass savings. As the spring compresses, the lower, bigger coils with lower rates, start coil binding and they are removed from the weight (and stiffness) equation adding even more to the weight savings at valve opening. This weight savings means that for the same application, you can use less spring pressure to have the same or better valvetrain control when compared with a cylindrical spring and that you can run higher rpms.
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| Here is the stopper in place. |
