Quote:
Originally posted by Pete C
Funfer2,
I broke 3 rocker shafts during open track events. I then bought Precision Pumps, chrome molly shafts and spacers and had no more trouble. Just to be safe, during my rebuild last winter I bought the end stands but having put many hours on the stock stands with the PP shafts and spacers I don’t believe that the stands were absolutely necessary. You can get the rocker shafts and spacers for a few hundred bucks.
The thin, stock shaft without end supports are surely a big part of the problem but contributing factors are high valve spring tension and over revving. If you don't have a rev limiter get one and check the valve spring tension. Finally, you don’t want to be breaking the stands cuz it will put pieces of rocker shaft and in my case, lifter pieces through the motor! For a few hundred at minimum to a little over a thousand you can save the thousands of $ that it will cost for a rebuild. A final note, change the oil and check for metal. Check the magnetic drain plug but also cut open the oil filter and check for filings!
Cheers, Pete C
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A little background, We had 7/8 dia. chromoly shafts and could not even go 5,000 rpm. without breaking. Now, with new material and no end supports, we've had no breakage at all, and that is with 700 lbs. of spring pressure!