Today, I will not comment about your next to non-existent intelligence, nor about your despicable sexual affinity to animals... Instead, I will give ya some reading practice, of something that I intended to include in the book but decided against. Not all engine stories are successful, we all know that and if not, we haven't built enough of them or we're lying!
Jim K.
There are good days and bad days …like this one!
So, the engine is built and tested and you’re enjoying it off and on the track. In fact, it turned out so good that you keep pushing it harder every time, looking for better lap times –aren’t we all! You’ve set the shift light to 7400rpm and at those revs, all you hear is music. And the music gets even better as you venture closer to 8krpm –the hell with the shift light! You are so mesmerized that you forget little things like the standard valve springs. Remember, std engines have a 7krpm cutoff for a reason. The people who decide these things know a hell of a lot more about mechanical limits than you or me. At some point, you feel a misfire, you slow down and leave the track. You check plugs, injectors, ecu… can’t figure it out so you decide to drive home on 5½ cylinders. Someone up there must be on your side, because you got home after 65km at ~4200rpm. To be exact, a mere 300m from home when it happened! A quick ‘thud’ and instant lockup. At first glance, the expansion tank is empty, so it doesn’t take a genius to figure a liner broke –at the very least! And that was the end of my 3.2liter. I did enjoy it for a few good years and I had thought that it would be the last engine ever for my 75’s but it seems fate was laughing in my face.
To make a long story short, I still haven’t decided on the exact cause of this mechanical disaster. Two possible causes are valve spring float and a dropped valve seat. I believe it started when a valve was bent, by either hitting the piston or a partly detached valve seat insert. The bent valve survived for the 65km trip home, but metal fatigue ultimately took its toll and subsequent catastrophic events took only a few milliseconds to unfold.
The mechanical autopsy revealed what you see in these pages. All this, was a result of not setting a rev-limit during the dyno/mapping session and driver… indifference –I can think of several stronger words.
Life goes on and the engine is being rebuilt. Fortunately, the 3.2 crank was intact –these things are getting rare- and so were the rods. However, I replaced the small-end bushings as the one in the affected cylinder (#1) had spun. In short, new valves, new Supertech springs, new CPS pistons…. Had I loaded the car on the flatbed instead of driving home, the cost would be considerably lower, 10 times lower to be exact. Oh well, water under the bridge now.
The point of presenting this unfortunate mishap, is to show that even this cylinder head damage can be effectively repaired, so don’t despair if you ever find yourselves in a similar predicament. Sure, it will take some careful grinding to restore proper chamber volume but that is a minor inconvenience when compared to having to fully modify another used head! And in closing, here are my sacred last words:
always map a safe rev-limit!