Got it all ready to adjust rods {24tpi} know its 3.6 turns, my question is how do I know for sure cam lobes are all the way down, turning the tire and can see both valves closed on cylinder, rock the tire and all that, just looking for absolute cam lobe bottom

 

It isn't all that important. The cam is at the bottom of the circle for a good length of rotation, not just one magic spot. Just rotate the motor until the valve closes and isn't moving any more and that is the base circle.

 

didnt think it was, but was checking for a guru answer

 

Also, I think you need 2.5 turns from zero lash in order to get .100" into your lifters, 3.6 would give you .150"...

 

What I do is get the piston at TDC for the one I am working on. Pretty easy on the front cyl. if you take out the timing plug. There is a mark on the flywheel for TDC. You can also take out a spark plug, and stick a plastic straw in the plug hole to feel when the piston is at TDC. Just rock the wheel back and forth a little and you will feel it. Then for the rear, turn the wheel forward until you feel the piston at TDC on the rear cyl. It works for me.

 

Just make sure your lifters are pumped up before you do the adj If you don't know how ask us

 

Good God got to move from 1666 Ok how's Rufus doing /is gas going down to 2.79 a gallon by 3/6/2011 ?

 

Your gonna have the plugs out anyway and I have the Chrome timing hole cover over mine so I just use a twisted pipe cleaner to reach in and feel top dead center. Rule of thumb is to just put a decimal in between the number of the pushrod TPI Which in your case is 2.4 turns out. This will give you the 1 inch sink which is half of the total 2 inches. I know some people do put 3.6 turns on a 24 which will sink it almost 1.5 inches instead. I have rivera taperlites with 40 TPI and the directions say 4 full turns.

 

3.6 {.1499 depth } and I went with 3.0

 

It's just math, guys. I like that "stick a decimal in it, it's done." That's slick. I'll have to remember that one.

1 inch / 24 threads (full rotations) per inch = 0.041666 inches per thread (full rotation).
0.100 inches / 0.041666 inches per thread (full rotation) = 2.4 threads (full rotations)
2.4 rotations * 6 flats/rotation = 14.4 flats. So, 14 and a half flats from zero lash and you're there, or 2.4 rotations on a 24 TPI pushrod.

Do the same thing with 40 TPI and you get 4 rotations, 24 flats.