Re: 1929 to 1932 Motor Camshaft Rocker Levers - the improved type

Posted by Odd Moen On 2015/9/27 13:43:28

I changed from stamped to forged rocker arms on my 1929 633 Touring for some month ago. After changing the rollers and pins on the forged type, I measured, more or less by an accident, the center of the shaft to the center of the pin on the both type of rocker arms, L1 and L2 (see sketch). It was a surprise to detect that this measure was app 1mm longer on the forged type (I have forgot the exact figure). I checked lot of rocker arms. A longer rocker arm mean that the valves will open earlier, which will cause a wrong timing! According the tune-up guide for 1929-30 the inlet valve, cyl 1, shall open 20deg before top dead center (see mark on the flywheel). To get the valve opening according to this information, I had to turn the camshaft gear 1 tooth clockwise. The "0" marks on the camshaft and crankshaft gears are now moved with one tooth from each other. The engine run perfect.
I did also change from stamped to forged rocker arms on my 640 Roadster, and I had also there to move the camshaft with one tooth in clockwise direction.
I have looked into the Service Letters but I haven`t found any information about this topic.

Has anybody else had this experience, or are some cars running with wrong timing?

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