Valve spring tech
(minor clean up) |
(Add text, image, links; clean up) |
||
| Line 5: | Line 5: | ||
This article will show how to set up the valve spring installed height to prevent coil bind and check/correct the clearance at the valve guide boss/seal and the valve spring retainer. Only simple hand tools will be required so that most anyone can do this at their home garage. | This article will show how to set up the valve spring installed height to prevent coil bind and check/correct the clearance at the valve guide boss/seal and the valve spring retainer. Only simple hand tools will be required so that most anyone can do this at their home garage. | ||
| − | == | + | ==Using an installed height micrometer, or "height mic"== |
| + | This tool fits in place of the valve spring. By extending the body, the measurement is taken from the side of the tool. This leaves your hands free and is accurate as long as the retainer-to-tool matches up correctly. | ||
| + | |||
| + | Care must be used to assure the mic is measuring from the same surface of the retainer as the spring bears on. If there's a problem with this, in some cases a shim can be used or a spacer made to compensate for any mismatch between the tool and the retainer. | ||
| + | |||
| + | The original [http://www.combo-flo.com/msp_hm.htm '''Hite-Mike'''] is available, as well as a cheaper alternative like made by Proform, [http://www.summitracing.com/parts/pro-66902 p/n 66902]. | ||
| + | |||
| + | ==Using a snap gauge== | ||
| + | Put a valve in the head, install the retainer and locks that will be used. Holding the valve tightly against the seat, use the snap gauge to measure the available installed height. | ||
| + | |||
| + | Once the available height is known, compare that to the valve spring installed height that is required to get the seat/open pressures needed for the cam to be used. | ||
| + | |||
| + | ==Correcting the installed height== | ||
| + | If the installed height is insufficient (and depending on how much more installed height is needed), a +0.050" lock can be used. If even more installed height is needed, there may be different retainers that will give more height, or the valves may need to be replaced with longer valves. In some cases the valve spring seat can be machined deeper. Use caution/consult the manufacturer to be sure the seat can be made deeper without hitting a water jacket or port. | ||
| + | |||
| + | {{Note1}}On Vortec and other heads using self aligning rocker arms, using a +0.050" lock can cause interference between the rocker tip and the locks/retainer. Rockers contacting the locks/retainer has been encountered using a combination of c/n 906 Vortec heads, Comp Pro Magnum rockers p/n 1317, Comp retainer p/n 787, Comp spring p/n 26918, and the +0.050" locks. | ||
| + | |||
| + | Mock up the assembly and check the clearance closely. In the case there's '''''insufficient''''' installed height, there are a few options: | ||
| + | *Use non self aligning rocker arms. Requires guide plates be installed. | ||
| + | *Use longer valves | ||
| + | *Use a different spring/retainer combo that uses a standard lock | ||
| + | *If just the locks are hitting the rocker, using a shorter (lash cap compatible) lock like the Edelbrock p/n 9615 may help. This 7 degree lock is 0.050" lower than a regular lock. | ||
| + | *{{!}}Use extreme caution if making the spring seat any deeper. | ||
| + | |||
| + | If it's found that there's '''''too much''''' installed height, there are a couple options: | ||
| + | *Use hardened shims | ||
| + | *Use a spring cup | ||
| + | *Use -0.050" locks | ||
| + | *Use "shorter" retainers | ||
| + | |||
| + | A tool to help determine the effect on installed height using different retainers and/or locks is the Howards Cams [http://www.summitracing.com/parts/hrs-92010 p/n 92010], shown immediately below: | ||
| + | |||
| + | [[File:Ret height92010.jpg]] | ||
| + | |||
| + | ==Measuring installed height without snap gauge or height mic== | ||
#A 6" to 8" length of small diameter welding rod or clothes hanger wire | #A 6" to 8" length of small diameter welding rod or clothes hanger wire | ||
#Wire cutters | #Wire cutters | ||
Your Privacy Choices