Cam shaft gears

flathead4rd

flathead4rd

Well-known member
I have the timing marks lined up on my cam shaft and crank shaft gear. Every thing looks good there. I also noticed there are fine line marks on the cam shaft and gear that don't lineup. Is this gear pressed onto the cam shaft? The cam is a Potvin 415 in a 296 CI Merc block. Do the 4 bolts on the cam gear have anything to do with aligning the marks? My first thought was that it had something to do with degreeing the cam? Any help appreciated.
 
The 4 bolts hold the gear onto the nose of the cam, it is not a press fit. You Should ignore any other scribed marks on the gear and or camshaft and degree it in. To do that you'll probably end up slotting the holes in the gear, once the timing is correct, pin the gear to the cam so the slotted holes can't slip. Then you know its right
 
The 4-bolts are in a pattern that guarantees that the gear can only bolt onto the cam in one specific direction. Hopefully you have the timing information for the cam and plan to degree it to see if it is advanced or retarded in your particular engine. The more advanced builders (whether professionals or personal) will degree the cam in to understand whether it needs to be advanced or retarded . . . and then take appropriate measures to dial it in. I do mine by drilling a new bolt pattern in my milling machine - using a rotary table. Others use offset bushings or as Brian noted, they slot the hole and then pin the gear to guarantee that it doesn't move.
 
Thank you Brian for your reply. I think I'll not make an changes to the way it is now. This engine was originally built by Mark Kirby of Motor City Flathead.
 
Thanks Bored&Stroked. I think I'll leave it as it is. I know nothing about indexing cams, so if it ain't broke don't fix it. This engine was built by Mark Kirby, Creator of the Aluminum flathead block.
 
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