Q&A / Tech

Mailbag: Troubleshooting Unwanted Lifter Noise

Q: Last year, I rebuilt my Ford 300 cubic-inch straight-six engine. The head was shaved .010”, the valve seats were reground, and the crank resized. The block was bored and cleaned also. The cam is a Competition Cams 260H grind with matched lifter, pushrods, and rocker arms. I also installed a new oil pump.

The problem is, I can’t get rid of an annoying lifter ticking. I adjusted the valvetrain according to the shop manual to put .030” of preload on the lifters. I also measured the gap between the valve tip and rocker arm tip; it is .150”—right in the middle of the .100”-.200” spec in the manual. I have 40-50 pounds of oil pressure under all driving conditions.

I’ve tried adjusting the rocker arms in .101” increments, but this made the ticking even louder. The volume of oil seems low; it just oozes out of the rocker arm pinhole.

Is that enough oil, or should it be more?

My engine shop assured me that every oil gallery and passage in the block was cleaned out, but something isn’t right. I’ve been told that 300 straight-sixes always make this noise, but a friend of mine is on his third one and all of them were quiet.

A: It sure sounds like you did your homework!

We only have two ideas to offer here:

  1. If you’re using roller rocker arms, you might want to check the geometry. Make sure the roller stays centered on the valve tip through the rocker’s entire motion. Also, make sure the rocker is not contacting the head itself or the valve spring retainer. Keep in mind that some brands of roller rockers are naturally noisy.
  2. The second thing to check would be oil aeration caused by improper clearance between the oil pump pickup tube and the bottom of the oil pan. The clearance should be between 1/4-inch and 3/8-inch. You should also check for air entering the oil pump where the pickup tube connects to the pump.

You’ve got questions. We’ve got answers. The Summit Racing tech department tackles your automotive-related conundrums every week in our  regular Mailbag columns. Click here to see them all.

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