545 build with roller cam

Hi Guys, I've got a new roller cam installed in the block, it easily rotates using my thumb and fore finger. When I start to install the cam sprocket it starts to bind up, the further I pull the sprocket on the harder it is to turn the cam. This happens before the sprocket even get within a quarter inch of the thrust plate , there's no contact there at all. The same thing happens regardless of which of the three brand new sprockets I try. Is it possible the dowel hole in the cam could be misplaced enough that the sprocket pulls the pin enough that enough force is there to pull the first cam journal out of round and make it bind up. It seems to get worse as the sprocket gets closer to seating on the nose of the cam.
I think I'm going to try to remove the dowel from the cam tomorrow and install a sprocket without the dowel just to see if the cam still turns easily. Any other ideas out there? Thanks in advance.  fordy8

The cam sprocket should not need to be “pulled onto” the snout on the cam!! Are you installing the timing chain when this binding up situation is occurring?

+1 sounds like chain bind. There must be play in the chain when installed or you will be replacing the cam bearings and #1 main bearing very quickly

No chain involved, and I've never had a sprocket just slip on, always a very slight interference fit.

Something sounds fishy!!! I’ve never had a timing gear that I had to use the retention hardware to pull the gear on but I’ve not built hundreds of engines so maybe I’ve just gotten lucky.

The cam gear hub outer diameter is hitting the cam plate inner diameter? Mark it with a sharpie, assemble and rotate to see where its making contact. I had that problem with a no name gear set on a mild build years ago. Not a roller cam but I have learned to only use Roll Master gear and chain sets.

Could the hole for the dowel pin in the cam be a little off? The turning resistance of the cam starts before the sprocket gets within a quarter inch of the thrust plate, the only things it's touching are the cam snout and the dowel pin. This happens with all three of the new, never installed, sprockets that I have. What else could it be? It's a Comp Cam. I can't get the dowel out. I'm thinking about trying to lightly ream the dowel hole in one of the sprockets to see if that helps. What do you think, bad move?

fordy8 wrote:No chain involved, and I've never had a sprocket just slip on, always a very slight interference fit.

I have conservatively handled over a 1,000 of 'em and if the gear does not go on the cam snout by hand pressure, something is not right; if it is aftermarket then anything is possible. That snout MAY be slightly to large.
Dowel pin diameter or miss-alignment is the most usual case.

fordy8 wrote:Hi Guys, I've got a new roller cam installed in the block, it easily rotates using my thumb and fore finger. When I start to install the cam sprocket it starts to bind up, the further I pull the sprocket on the harder it is to turn the cam. This happens before the sprocket even get within a quarter inch of the thrust plate , there's no contact there at all. The same thing happens regardless of which of the three brand new sprockets I try. Is it possible the dowel hole in the cam could be misplaced enough that the sprocket pulls the pin enough that enough force is there to pull the first cam journal out of round and make it bind up. It seems to get worse as the sprocket gets closer to seating on the nose of the cam.
I think I'm going to try to remove the dowel from the cam tomorrow and install a sprocket without the dowel just to see if the cam still turns easily. Any other ideas out there? Thanks in advance.  fordy8

Did you try fitting up the cam sprocket to the cam without the chain?

if you tried 3 differant cam sprockets,i would have cam checked!a little late on reply.