Howdy
A lacquer thinners works great for getting back into all the old sludge and crap. Get scrub the crankcase with a rag soaked in it, wiping it with a clean rag afterwards. Parts Cleaning guns with gas in them work great as well but can pose a risk in poor ventilated areas - this gets messy.
Very time consuming task task doing it if you don't want to get any of it on you - short stints work great.
Cheers
Billy
neglecting the ventilation and the mess, I use a pneumatic siphon gun from harbor freight tools to hose the innards down with mineral spirits.
be real careful using siphon gun and any thing flameable. ask me about the explosion and setting myself on fire using one. learnt my lessons real good that day.
Old set of coveralls, do-rag, goggles, painter's mask, solvent gun w/SOLVENT for God's sake, NOT gas:jaw:...messy, nasty, but it's the way to get an engine clean inside, probly not OSHA- approved...half barrel underneath, or lots of floor-dry, lots of ventilation, NO flames or sparks anywhere around...Stoddard solvent is not as flammable as gas or mineral spirits, if you can find it these days...wash from the top down, then from the bottom up, then top again, until the drips come out pretty clear...yeah, I've done this too many times-love in-frames...NOT!