Boy, I feel kind of stupid asking this question but since this is only my second roller cammed motor and the first retro-fit.....

I measured the clearance for the cam button by setting up a dial indicator at the back of the cam at the back of the block. I measured my .004 clearance and turned the back of my button on a lathe to create the correct clearance. When I installed my timing set and tryed to install my timing cover, it wouldn't fit. I couldn't figure what changed until I discovered when I tighten down the timing set, it pulls the cam forward. In 20 years of putting on timing sets and cams, building motors, etc. I never noticed that the timing cam gear is what sets the cam's rearward thrust. I always thought it was the back of the cam against the inside back of the block. Is this a correct assumption or am I missing something??!!?? If this is correct, why doesn't any manual mention to set the cam thrust clearance WITH THE CAM GEAR INSTALLED !! Pretty darn critical !!

 

The cam gear is exactly what keeps the cam from walking backwards. Now you know why they sell those torrington bearings that go between the block and gear too!

 

for the same reason the manual doesn't tell you dot to dot on the gears is firing on #6

 

Thanks for the help!!! One more thing....on a roller block with the cam retainer plate in front....what is retaining the cam in the rear then?

 

Nothing retains the cam "at the rear".

The cam can't go back into the block any farther than it's supposed to because the back of the cam gear runs into the front of the block, or in the case of the factory roller setup, it runs into the front of the retainer plate.

 

Possibly the reason cam end play isn't mentioned in a manual, is because there's nothing that can be done to adjust it with factory setups.
With the factory roller the thrust plate is sandwiched between the gear and the front bearing, and with the flat tappets, the cam is forced rearward with the front of the block being the thrust surface.
Either way, it's pre set. Unless you're using a button

 

Ah, of course! Now I'm good. Thanks for all the reponses. Back to the lathe.