If you’re planning a camshaft swap or engine work, it can be pretty intimidating because everything could go wrong. Human errors such as improper torquing, buying the wrong parts, or skipping steps can be detrimental to your build. One of the most common issues when modifying your vehicle is clearance, especially when discussing internal engine parts. Here’s one way to check your valve-to-piston clearance and avoid unwanted damage to your car’s powerhouse.
First of all, you’ll want to get your hands on some vernier calipers, which you’ll use to measure distances, along with a pushrod checking tool. These tools will allow you to check clearance to a near-exact measurement. You’ll also need a checking spring to ensure the lack of preload and slack in the lifter when checking the valve. Finally, you will need some Play-Doh; it might sound weird but trust us on this one.
Step one is to make sure the head gasket is in place, be careful not to torque the gasket down entirely, and bring the piston a full extension. Next, place the Play-Doh, a medium-sized blob about the size of your palm, on the top of the cylinder. Next, you torque the heads into place to the first torque step, which is about 40 ft/lbs on an LS.
Once everything is in place, get the pushrod checking tool mentioned above and ensure the camshaft is on the base circle. Next, fit the pushrod length checking tool into place and turn the engine over with a wrench to extend the piston up and down. After doing it a few times, take the pushrod checker out and remove the engine head, which will expose the newly-imprinted Play-Doh.
Now it’s just a matter of extending the piston completely and cutting into the Play-Doh to check the thickness of the indentation. Finally, you need to check the consistency with your caliper, making sure you cut into the thinnest part of the Play-Doh. The minimum clearance you should shoot for is one hundred thousandths of an inch on the intake and eighty-thousandths of an inch for the exhaust valve. Once you’ve completed this test, you should know how much clearance your engine valves will have and whether adjustments need to be made.
Elizabeth is hardcore horsepower enthusiast with unmatched intensity for making things faster and louder. She wakes up for power and performance and only sleeps to charge up for the next project that’s heading to the track. From autocross to drag racing, Elizabeth is there with you, so stay tuned for her unique perspective on horsepower news, builds, tech info, and installs — with her, it’ll never be boring!
