We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.
Engines

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

How do I Find Top Dead Center?

By Lori Kilchermann
Updated: May 23, 2024
Views: 9,090
Share

To find top dead center in an internal combustion engine, it is necessary to stop the movement of a piston. Typically, most engine builders will choose to find top dead center with the No. 1 cylinder. Using a dial indicator gauge and a crankshaft socket, it is possible to find the top dead center of a piston's stroke by taking a reading on the dial indicator while turning the rotating assembly. Once located, it is much easier to find top dead center by using a piston stop bolted to the engine block and adjusted to just come into contact with the top of the piston when it's at the very top of the stroke.

It is very important to find top dead center of an engine's stroke in order to set the ignition timing. All ignition timing is set and adjusted according to the piston's relation to top dead center of the crankshaft's stroke. Once an engine is running, the ignition timing can be set using a timing light and the reading from the harmonic balancer. Initial start up requires the engine builder to find top dead center and set the timing to fire at that point in the engine's rotation. All final adjustments can be made once the engine has been started.

If an engine is mounted in a vehicle and the cylinder heads are in place, it is still possible to find top dead center. After removing the spark plug wires to disable the engine and prevent accidental start up, the No. 1 spark plug must be removed. Once removed, a small screwdriver can be inserted into the spark plug hole, and the engine can be rotated by turning the crankshaft pulley. This can be done by hand or by bumping the starter. While the engine is rotating, it is necessary to hold onto the screwdriver and feel when it contacts the piston to find top dead center.

When the piston contacts the piston stop, it will begin to be pushed up and out of the spark plug hole. At the point that the screwdriver ceases to be pushed up and out of the cylinder, the engine should be gently rocked back and forth by hand. When it feels like the screwdriver is neither going up or down, the search to find top dead center has been completed.

With the engine in this position, the spark plug can be reinstalled, the plug wires can be reattached and the ignition rotor can be positioned so it is pointing to the No. 1 spark plug wire. The vehicle should then start and run. Now, the ignition timing can be set with a timing light.

Share
WikiMotors is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
Share
https://www.wikimotors.org/how-do-i-find-top-dead-center.htm
Copy this link
WikiMotors, in your inbox

Our latest articles, guides, and more, delivered daily.

WikiMotors, in your inbox

Our latest articles, guides, and more, delivered daily.