Cam chain install question

[bears56sc]

I just bought a 80 CJ7 with a AMC 304 . The motor had jumped time so i prepare to change the timing chain and gears, which i have done a few times before on small block chevys. I get the cover off, chain is very loose and it had jumped time and the cam gear was coming apart, which is probably a good thing that its the chain and gear and not the cam or crank or anything bigger. So i get the old gears and chain off, put the new gears on line up the marks (cam gear mark at 6o'clock and crank gear at 12o' clock) then pull them back off put the chain on them and install again. I had to order my gaskets and they wouldnt be in til tommorrow so im done for the day. i was reading thru my haynes repair manual and it shows after installing the chain to turn it til the cam gear is at 3o'clock and the crank gear is at 6o'clock with 20 pins in between them. ive never seen this before? Should I turn it like that before i put my cover back on? Why do they show to do that? Is it so you can retard or advance the timing? Im new to amc motors so any help is greatly appreciated! thanks in advance for the help

 

[priceg]

With the dots lined up the cam key-way is at 10 o'clock and the crank key-way is at 2 o'clock

 

[CJ]

20 and 21 pins are correct after assembling at 6 and 12 and rotating. See this post -->> http://www.jeep-cj.com/forums/f2/properly-setting-time-937/

 

[bears56sc]

Thanks for the help guys. Much appreciated!!