VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc 1928 Timing Gears

It has come to my attention that the camshaft fiber timing gears for 1928 are no longer being reproduced. I guess that leaves us with whatever NOS stock is still out there. The only other alternative I am aware of is facing down a newer 7/8" gear to 13/16" and using a step key in the camshaft. Has anyone attempted this approach?

Of the three aftermarket NOS fiber cam gears that I have encountered, they are all marked between the 14th and 15th tooth counter clockwise of the keyway. This is contrary to the documentation I have and the very informative engine rebuild thread by AntiqueMechanic. (See also Service News for proper location of timing mark). Evidence would suggest the timing mark on the cam gear should be on the 15th tooth. What is going on with these NOS gears?

Now the interesting part. My 1928 motor has one of these mismarked cam gears installed. Click Here to see how the timing marks are aligned. This picture was taken several years ago. In case it's not clear, the crankshaft gear is marked with four dots on the tooth immediately clockwise of the original timing mark. Aligning this mark with the matching mark on the camshaft gear, this engine would seem to be running with the valve timing advanced by one tooth. My research of this condition has revealed that opening and closing of the valves sooner than recommended may lead to improved low and midrange torque while sacraficing some high end. Could this engine have been assembled this way intentionally for this purpose? It has always been a good running engine with plenty of power in the hills and flat lands. I happen to know that this engine was assembled by a well-known Chevrolet mechanic and VCCA member in the L.A. area who has since passed.

I am preparing to assemble another 1928 engine but review of my notes and pictures from prior experience has left me scratching my head on this one. Any thoughts appreciated.

Ron

The old antique mechanic is likely the best qualified to comment but that does not stop me. I have not had personal experience, only over the phone with a 30+ year mechanic working a '26 engine. He claimed the problem with the poor running was the carburetor and a qualified mechanic had rebuilt the engine several years past. I knew the carb was ok and advised to check the timing gear position. The car had little power, idled and ran poorly. Eventually he pulled the timing cover, verified the timing marks aligned, changed the position based on counting teeth from the keyways and wallah. When reassembled, it ran smooth and strong.

Now the story is on an engine with a standard grind cam. No telling what the old Chevy mechanic put in for a cam. I might suggest blueprinting the cam before making any changes from what has proved to work.