For a parts diagram, go to Messick's.com on the internet. At the top of their home page:
- Click on parts diagrams
- Click on New Holland Ag.
- Enter your model number (4100)
- Click on 1975-1981 4100
- Ckick on fuel systems
- Click on fuel injection pump
Ebay often has service manuals for sale for Cav injection pumps. A pump manual would certainly provide much more guidance than a parts diagram. You would have to be careful to select a manual representative of your pump model. Re-sell the manual when you're done with it.
Another thing - there are three timing marks under the timing gear cover that must be aligned when you reinstall the injection pump.