Valve Adjustment on B21/B23/B230 "Red Block" Motors
Incorrect valve adjustment can result in low performance, poor economy, and noisey engine operation.
Valve adjustment should be checked every 60K miles and for engines with a good maintainance history adjustment typically is only occasionally required. A valve adjustment check is done properly when the engine is near operating temp, around 150-180 degrees. Run the engine up to normal temp, turn the engine off and remove the top cam cover. A good service manual is a must at this point as well as a set of feeler gauges. I personally prefer the Go/no-go style gauges since you can quickly determine if the valve is in spec or not, and if not how far off it is.
Speed is of the essence since the motor will cool and the specs will change, however the debate rages as to whether a cold adjustment is as good or better than a hot adjustment. When checking each of the valves is will be necessary to rotate the motor, some will find it easier to do this with the spark plugs removed. You can also locate the starter test wire under the hood and use a starter test switch to engage the starter to rotate the engine. Take caution when using this approach, do not leave the key in the ignition, and for manuals be sure the transmission is in neutral with the emergency brake set and the wheels blocked.The Ipd starter test switch includes a user guide to locate the starter test wire under the hood for 200/700/900 models.
Generally a new cam cover gasket is required as well as few special tools. We recommend using the Ipd valve adjustment shim kit and the special ‘J’ wrench and valve shims as well as an instructional guide on how to adjust the valve lash. A measuring device, such as a digital caliper, is also necessary to measure the old shim vs. the new shim. For instance if the desired valve lash is 0.0015 inches and the current lash is 0.0023 inches we would simply add 0.008 inches to the current shim. If the current shim is 0.150 inches then the desired shim would be 0.158 inches. Typically you will not find a shim with the exact thickness desired, in this case the closest shim is selected and usually will only be 0.001-0.003 inches off.