Why Rocker Retainers?
TLDR: Retaining the rockers is not a fix for losing valve spring pressure. It is an security mechanism for stopping the rocker from dislodging when valve spring pressure is lost.
The problem with a floating roller rocker
The rockers in many cost effective cars from Toyota (and Subaru) are not captive. That is, the rocker is only held in place by spring pressure. Most of the time this is fine, however, under a condition where spring pressure is lost, the rocker becomes unloaded and can “walk-out” of position.
If you’re lucky, the rocker will find a cozy home in the head, the spring will stay in place, and you’ll only experience a misfire while the cylinder continues to operate on the second valve. However, if the rocker gets picked up by the camshaft, all sorts of damage can be done including punching holes in the tapet cover, dropping springs and ultimately, destroying engines.
In a perfect world where the valve spring can maintain control of the valve at all times (and you’re a perfect driver) there is no need for a rocker retainer clip. Based on the valve train geometry, weighting and desired RPM you can calculate the ideal spring pressure (which the OEMs do). In this case, the rocker will always be loaded with spring pressure and will stay in place.
However, in the real world, there are edge cases that you can’t account for with math. It’s impossible to eliminate and have the perfect spring which controls the valve 100% of the time.
The underlying problem...losing valve spring pressure
Different conditions where valve spring pressure can be lost:
- Valve float (inadequate spring pressure)
- Valve bounce (harmonics/natural frequencies issue)
- Valve stick (carbon build up)
For these edge cases, the clip adds an “insurance policy” by holding the rockers in place for the split-second spring pressure is lost. However, if you’ve got severe loss of spring pressure, adding a rocker retainer clip would only be masking the issue.
You’re totally right in saying that not every engine is going to have a rocker failure, nor does every engine have an oil failure. It's just something to be aware of, especially when you’re wanting to get more out of the engine.
What we’ve made is nothing super new. More expensive, high performance engines with this type of rocker arrangement run a clip from factory to prevent this issue. For example;
- Lexus 2UR-GSE in the LC500 (woah, what a masterpiece of an engine)
- BMW B58 in the Supra (shown in Papadakis’ video here: https://youtu.be/MckxlP60cnY?t=477)
Examples of Dropped Rockers
“Wish I knew about this sooner…
I found out the hard way...I started my Toyota 86, heard some sound...didn't think of it much and then on my 12 min drive to my appointment, i noticed smoke and a trail of oil... FML.
I just had it rebuilt, 2014 engine with 17+ valvetrain parts and upgraded non-beehive springs. But it still fell off. Literally, 5.8k kilometres and this happened…
I mean if you are OK with taking the risk then go for it, but for less than $1000, I rather have peace of mind.
This is a no brainer investment.”
- Ricardo before he knew about and ordered our FA20 Rocker Retainers.
Who's Running Rocker Retainers?
See how people like you have improved the reliability of their engines with our Rocker Retainer Kit
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