Updated at: 21-07-2022 - By: Lucas

Changing the spark plugs in your car’s engine is a common task for automobile owners. The installation of the spark plugs might be difficult because of the many parts and instructions required, therefore it’s crucial to know how tight the spark plugs should be when installed.

A tighter fit can help keep your spark plug in place for a long period, preventing problems from developing while the car is still in its infancy.

There should be just enough room between the spark plug and the engine head to insert a thin knife blade when testing a spark plug for proper tightness. To make certain the spark plug is properly seated and not too tight or loose, use this method.

Spark plugs should not be overly tight or too loose for a variety of reasons:

This can happen if your spark plugs are either too loose or too tight, causing oil to leak into your spark plug tube. While driving, oil leaks can generate heat and ignite a fire, resulting in damage to other engine components.

In order to avoid pinging and banging noises, it is also necessary to maintain a proper spark plug torque. When you remove a spark plug using a spark plug wrench, take careful not to damage any of the cylinders that are connected by a push rod system.

In addition, the engine’s lubricating system may be adversely affected, causing issues for you. Keeping this in mind, you should also be aware of the specific steps involved in changing your car’s spark plugs.

In the absence of a torque wrench, the drawing and wording on the packaging of every reputable spark plug manufacturer show what angle the spark plug should be pulled from the point of effortless twisting with your hands.

When a torque wrench isn’t available, the makers provide guidance and an image on the packaging. Just look around the packaging and you’ll find it, with some exceptions of course, from NGK and Denso to Bosch and Denso.

A clean and transparent spark plug tube should always be checked for leaks. They need to be replaced as soon as possible if they are excessively tight or leaking oil in your engine. In addition to the pistons, the tubes in your car’s engine are susceptible to failure if there is a problem.

What is the proper torque for spark plugs?

How Tight Should Spark Plug Be (2)

Installation torque for all spark plug types, including copper and classic platinum, ranges from 3.9 to 4.05 pounds per square inch (PSI).

Can the spark plugs be overtighten?

Overtightening the spark plugs can bend or shatter valves, therefore it’s never a good idea. If you overtighten a spark plug, you run the risk of bending or breaking your engine’s valves.

You’ll notice a big difference in how your engine runs if one of them is bent or broken. The pistons and/or valves can also accumulate carbon deposits as a result of this, reducing the efficiency of your vehicle over time.

What happens if spark plugs are not tight enough?

It is possible for your spark plugs to vibrate against the engine head if they are too loose. As a result, driving to the point where you are unable to accelerate or decelerate properly could result in a broken piston in your engine. As a result, appropriate spark plug tightness is critical to engine performance.

What happens if spark plugs are not tight enough?

Your car’s spark plugs should have a spacing of between 0.040-0.045. Misfiring from low or high rpm can be caused by anything else, and this can damage your engine in the worst-case scenario. Before inserting new plugs into an existing hole in the engine’s cylinder head, be sure to measure its diameter with a wire gauge.

How do I know if my spark plugs are too tight?

How Tight Should Spark Plug Be

Hard starting, low RPMs, or odd misfires are all signs that a spark plug has been overtorqued and has to be replaced.

What is the proper torque for spark plugs?

Installation torque for all spark plug types, including copper and classic platinum, ranges from 3.9 to 4.05 pounds per square inch (PSI).

Can you tighten a spark plug without using a torque wrench?

To tighten a spark plug, even though some manufacturers recommend doing it without the use of a torque wrench, you cannot do so since most engines contain an adjustment bushing that will maintain the shims in place and therefore prevent overtightening. Your engine will suffer harm if the spark plugs are overtorqued as a result.


The longevity of your engine depends on the tightness of your spark plugs. When installing a plug, it is not required to screw it all the way in, as this weakens the thread’s fragile structure, which can cause major damage to the plug as well as the engine’s groove. Tightening spark plugs does not necessitate a great deal of practice or extensive reading of specialized manuals. Be cautious and familiarize yourself with the instructions provided by the manufacturer.

The material used by the manufacturer to make a spark plug with a different number of valves may be the most important aspect. Spark plugs for 8-valve engines are typically made of copper, whilst those for 16-valve engines are typically comprised of platinum and iridium. To remove the plugs, you’ll need a smaller wrench.