Chasing The Weak Link

Chasing The Weak Link
By Don Terrill (c)2005

Improving a race engine can "easily" be accomplished by finding the weakest link and fixing it, but as with a chain, is a never ending task.

The Weak Link in Air Flow -
Perhaps the most difficult weak link to find and fix is the one limiting the airflow potential of your cylinder heads. I've ported heads for almost 20 years now and have been flow testing at 2am, trying to find an improvement, more times than I can count. Most of the time I was up that late because I refused to quit without finding some airflow. I would do test after test without any improvement, and then all of a sudden, the port would pick up a bunch. What happened? I finally found the part of the port that was holding it up - the weak link.

The Weak Link in Reliability -
I remember a while back when valve breakage was a real problem. Why had this happened? If you look back at the progress of the OHV racing engine you'll see the continual increase in valve lift without much increase in spring pressure. Well, with more lift and not enough spring pressure you get more valve bounce, which eventually leads to broken valves. So, what did the racing world do? That's right, better springs with more pressure. Then what started happening? Broken lifters! You see, you can't win, you can only continue to chase the weak link.

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