hd 21 timing specs

I am working on a old Allis Chalmers crawler model HD 21. I need the specification for valve opening and closing ie. open at x # of degrees BTC { before top center} close x# degree's ABC {after botton center} The engine is a 21000 Serie's engine with turbo. The fuel pump was 13 degree's early and the pistons were hitting the valves and after about 20 hours they broke the crankshaft. "can't figure how it went that long " back yard mechanic's !!!!!

Intake valves open BTDC 28degrees
Intake valves close ABDC 48degrees
Duration 256degrees
Exhaust valves open BBDC 53degrees
Exhaust valves close ATDC 23degrees
duration 256degrees
over Lap 51degrees.
To run the check set the tappets at .023inch

running clearence for valve tappets
intake .015 hot .018 cold
exhaust .020 hot .023 cold

I have 3 21s here on the farm , my toys
21 cable with 855 three vale engine
21A cable with a Mark 2 in it
21A hyd with a mark 2 in it

Bob Southern Ohio

This is the data I needed, It appears that it is timed one tooth ahead off the marks' Will find out as the crank is broken.--- { now they tell me it had a very loud knock !!!! }. I didn't start it as it was about -5 and batterie's almost dead. Turning it with the starter. I could hear three clicks each round and feel it as I gripped the rockers after the intake started to open. I pried up on the pushrod end of the intake rocker to check amount of valves to piston clearance about .080''-.100 '' Just before TDC it started to decrease and at about 15 degrees ATDC there was zero clearance the intake valves were bottomed onto the piston head, and remained that way for another approx 15 degrees before loosening. The pump timing is also 12 degree too far advanced.. Thanks for the spec's now I know the rest of the story and why the crank failed.