We see a lot of broken stuff. And it seems like each week, we see something new.
This week, for example, I noticed the cotter pin on the rocker shaft on Alexander’s 1275 engine was perilously close to walking out. (His car is here from Florida for a bunch of sorting and upgrades). One leg of the cotter pin appears to have already found its way into the sump, with the entire pin (and washers) were about ready to leap out.
This engine ran very strong and had a lot of upgrades with speed and power in mind. However, some of the execution left a lot to be desired. The cotter pin was a clue that more might be amiss… with the valve cover off to adjust the valves, we could see that there were other big issues, in fact, the rocker arms were wandering all over town.
The video below illustrates a worrysome wobble.
This much play in the rocker is a very bad thing and dramatically diminishes whatever precision valve operation might have once been present. A wobbly rocker will cause this contact pad to wear unevenly and ruin the valve, or even bend a push rod. A catastrophic engine failure might even follow.
So what caused this rocker to be so wobbly?
Ordinarily, a rocker arm on a Bugeye (or any Spridget) uses a soft metal bushing inside that rides on a harder rocker shaft, allowing for smooth operation. The photo above is an example of a rocker arm with the correct bushing inside.
However, whomever built this particular engine decided to use a needle roller bearing in place of the soft bushing. With the correct bronze bushing, the bushing is a much softer material than the rocker shaft, meaning the bushing takes on the brunt of the wear. With a needle bearing, the rollers are also hardened, meaning there is no longer a wear item. The result is an incredible amount of damage being done to the rocker shaft, as you can see in the photos below. You can even see the pattern left behind by the needles in the bearing on one of the areas!
A hardened rocker shaft might have helped resist the hardened needles, but we much prefer the unhardened shaft with the bronze bushings. That way, the shaft is sacrificial and the bronze bushings tend to last a good long time.
We do not know why the previous engine builder on this car decided to use needle roller bearings instead of the correct bushings. Perhaps he thought the needle bearings were more robust than the proper bushing and were thus better for high performance applications. Either way, changing the rocker assembly to a good one with the proper bushings installed will ensure this valve train operates at peak efficiency for many miles to come!
