I need to tighten the head-bolts on my car engine.

The mechanic tightened the head bolts on the engine.

I need to tighten the head bolt on my car engine.

I need to tighten the head-bolt on my car engine.

I need to tighten the hex head bolt on the machine.

I need to buy some hex head bolts for my project.

I need to install the head bolt heaters on all the engines.

The head-bolt heaters are essential for cold weather engine starts.

I installed a head-bolt heater in my car to keep the engine warm in cold weather.

I installed a head bolt heater in my car to keep the engine warm in cold weather.