RE: 1/2A Diesel Engines?
You want to run a diesel as lean and undercompressed as it likes. Overcompressed is how you break engines. Rich is like overcompressed. You may have to start the engine rich and overcompressed, but, as it warms up, back off the compression and it will speed up, then lean it a little and it will speed up, now try backing off the compression a little more. etc. etc. Once you get it where you want it leave it alone as much as you can and use your starter.