Engine Building Fundamentals: Checking for Size and Straightness
Checking for Size and Straightness
- In many instances, when it comes to building a performance engine, we'll be relying on reusing some of the existing engine components.
For example, in a mild performance build, we may be retaining a factory crank shaft and replacing the factory pistons and con-rods with stronger parts.
If we're performing a freshen-up of an existing engine build, on the other hand, we may be keeping all of the existing components.
In any case, we want to start by ensuring that the components that we're using are straight and on-size.
Even if you're using all new components in the engine, it's still essential to actually measure and confirm that the parts are correct and what they're supposed to be.
It's tempting to assume that new parts will be correct straight out of the box, but more often than not, this proves to be a bad assumption, and it can waste a lot of time, and potentially damage your freshly-built engine.
While this is work that we can adequately perform in-house with some basic tools and fixtures, many engined-builders may opt to leave this work to their machinists.
This will involved measuring all of the bearing journals on the crank shaft for size, as well as confirming that the crank shaft isn't bent.
If the crank shaft passes these tests, then it's suitable for use in the engine.
Likewise, it's also advisable to confirm that the con-rods are straight, the big ends and small ends are on-size, and the link is correct and consistent across the entire set.