Brian,
I agree completely with Bob Jones! How can you tell if the hollow parts of
your crankshaft are truly clean if you don't take the plugs out?
Every MMM engine that I have worked on in recent years has had its
crankshaft full of cooked on carbon. Its tough stuff to remove and you don't
get it with a brush! Removing the plugs is also a difficult and time
consuming job but it is essential to cleaning the crank. If you don't clean
the crank then the odds of getting a chunk of dislodged hard carbon in your
nice new rod bearings or the rear main are quite high.
I don't worry about the plug material any more as the modern balancing
equipment is so good that you can balance out the weight difference without
changing the plug material. I make mine out of brass about 8 inches at a
time. (Its hateful to be reminded what eight inches really looks like). The
thread is 1" OD x 16 tpi, don't forget that the pitch angle is 55º, not the
American angle of 60º.
Don't even try to save the old plugs, you're going to ruin them anyway! I
always drill them out using as many drills as necessary to get as close to
the threads as I have to without touching them. I usually start with an
eighth inch drill and increase the size until I can jamb a reasonably large
stud remover in the hole and screw the plug out. When you've got the plugs
out, the cleaning can take you another 40 hours on a four cylinder crank.
Good luck and keep smiling. Please let me know if I can help in any way.
Cheers, "Bob".
"Accept the fact that some days you are the pigeon and other days you are
the statue".
----------
>From: Kellmg@aol.com
>To: mg-mmm@autox.team.net
>Subject: Crankshaft Plugs
>Date: Fri, Mar 31, 2000, 1:50 PM
>
> MMMers
>
> Have any of you had the experience of removing the oilway plugs in the
> crankshaft?
> On the PType there are four. On mine two aluminum, two steel. In Bob
> Jones's article in Malcolm Green's MG Road Cars, he states, it's one of the
> most important jobs in a MMM rebuild.
>
> Having had a bristle brush down through the oil galleys, there seems to be no
> sludge build up what so ever. Having already purchased the threaded bar
> [Mike Dowley] in aluminum {only] I question if the removal of the plugs is
> necessary. The machinist here in the States doesn't have the required tap,
> should any mishap happen during their removal. What's the thread size on
> this? How many of you were fortunate to unscrew them? How many of you
> decided to leave them be?
>
> My conrods came in yesterday, from Carrillo. Three month waiting list, but
> well worth it.:):)'s
>
> Any input appreciated.
> Thanks,
>
> Brian Kelly.
>
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