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6 Cylinder Head Assembly Tips
All things under the hood of a car have an inherent delicate nature and require special tools and knowledge to fix, but there are a couple engine components that carry the bulk of the responsibility in keeping things running smooth. One of them is the cylinder head. One small error or omission can lead to the need to re-do all the work you’ve already done or worse—expensive engine failure. When putting together one of the most delicate and sensitive parts of your engine, here are six things to keep in mind.
Double-check the order of operations
If there was ever a time to think through the whole project and align what needs to be done into an order that makes the most sense, this might be it. Each step builds on the prior one, and the consequences of proceeding out of order often means having to re-do what you just did. For instance, if I had checked the valve spring installed heights prior to cleaning these heads and lapping in the valves, the initial measurements would be meaningless because the seat and valve positions have effectively changed. Make a plan that considers everything, sleep on it, double check, then get started.
Clean, clean, and then clean again
Once the order of operations is decided and locked in, be sure you have a full cup of coffee before cleaning everything. Cleanliness is critical to proper setup due to the precision required in cylinder head assembly. A long time ago, I heard someone say “an engine can ingest a lot of dirt and still run, but it cannot tolerate having dirt built in,” and with every project I have done since found that saying to be more and more true.
It’s easy to get sloppy
While the exacting width of contact between a valve and seat is not hyper-critical in the vast majority of engines, it might be for yours. Fudging numbers during assembly—especially if you don’t write them down—is asking for diagnostic headaches later.
Also, even the lightest cylinder heads are hefty and feel very durable. Yet nearly every surface of most cylinder heads has some type of sealing or machined surface that should not be damaged. Picking up and moving a cast-iron big-block head across a workbench is a real pain, but dragging it and putting a gouge in a sealing surface is worse. What feels like extra effort in these operations rarely is, and will always pay off.
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The tools matter
Many automotive projects require special tools, but there are often workarounds for a one-off project where expensive tools just don’t make sense. This is not one of those times. To properly assemble the heads for my LS engine—one that is pretty simple relative to some other mills—I still needed a spring checker, spring micrometer, and spring compressor. That’s in addition to a handful of more common tools like caliper micrometers and the materials to lap in the valve faces and seats.
Of course, it does not always make sense to purchase every special tool needed, so don’t discount borrowing or bargaining to get access to what you need when you need it. I’ve had good luck working with my local machine shop to occasionally borrow tools or use things onsite, but that only comes with a good rapport and repeat business. Plus, one job was something the shop plain did not want to do. All this having been said, in my latest V-8 project, a deep socket took the place of a seal installer but required a lot of care to prevent needing to source a replacement seal or two. Improvise carefully.
Trust but verify
I trust the company that I ordered valve springs from to send me valve springs. I even trust that the label is true to what’s in the box. However, there is never anything wrong with taking a minute or two to confirm that you know the parts going into your engine are what you think they are. Checking valve springs for install height is a slightly tricky process for first timers, but it ensures that the whole combination will work as designed and expected.
Prepare your patience
This is precision work that involves more than a few fiddly parts. Installing valve springs involves those tiny, fiddly valve locks, and halfway through is not the time to lose your temper. If it gets frustrating or brain fog rolls in, it’s often best to simply take a break. Use the time to either think through the stumbling block or completely forget about it for an hour while you have a snack and recharge before trying again. Frustration often leads to cutting corners, but as previously pointed out, now is not the time to cut corners.
The process of assembling cylinder heads is involved and complicated, no two ways around that. But it can be very rewarding, and is something that is possible to do yourself at home with a little preparation. The results will be an engine that runs great and the satisfaction of having made that happen yourself.
After seeing that LS head, I realized it was [6] cylinder head assembly tips and not [6 cylinder head] assembly tips