66 mm Crankshaft soft plugs

[gh914]

I am working on building my first six. I have been building four cylinders for years. My question is on the soft plugs for the 66 mm crankshafts. I have a real nice std/std counterweighted crank I plan to use in a 2.0 liter engine.

I believe I count a total of 8 soft plugs in the crank.

Two inside the flywheel flange that are drilled straight in
One straight into #2 main bearing journal in line with one of them from behind the flywheel
One on an angle through #2 rod journal
One on an angle through #3 rod journal
One on an angle though #4 rod journal
One straight through #6 main journal in line with the hole through #7 main journal.
One straight into the back end of the crank

Does this quantity look right? Do all of them typically get removed for cleaning?

I am curious on the soft plugs that are drilled straight into #2 main and #6 main journals. How do you get into those to remove the soft plugs and then tap them for the threaded plugs?

Thanks

[john walker's workshop]

Sleeping dogs come to mind.

[Neil Harvey]

Seems like an odd reply to your question.

Here is another way to look at this.

The crankshaft supplies oil to the rod bearings from either end of itself internally. It is the last mechanical part of your engine to see oil before the Rod bearing shells. Do you want to know everything about your engine before its re assembled? If so, then the reply above should not be taken into account. To me it reads like, don't bother leave it alone. Contrary to my statement.

But there are some considerations to be known.

Make sure you remove all the debris after drilling out the plugs. Otherwise something left in there makes the whole process no better than leaving it alone.

Do not tap the galley holes all the way. Make sure the set screws you use bottom out. Otherwise I cannot imagine to issue getting it out.

The early cracks have a really odd oiling distribution. There are 6 plugs I think from memory. The flywheel face has 2, 1 up the inside of the crank nose and 3 in cranks, #2 , #3, and #4.

Here is were it gets odd. The rear rod journal, (#3) and the front journal (#4) get direct oiling as the galleys intersect directly. Rods 6, 1, 2, and 5 are oiled from drilling that are tangential to the main galley drillings. Its common on these early cranks to fully groove the center main and cross drill it. It helps get a little more oil to the 2 center rod bearings.

As you get longer in the stroke with larger journals the angles of the cross drilling becomes better and more direct intersections.

Oil can travel from either end to either end. You can check this with compressed air.

Good luck and just make sure you remove all of the drillings etc.