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Discussion Starter · #1 ·
As most of us BB owners have l

As most of us BB owners have learned thus far during ownership, these horizontially-mounted distributors are prone to advance weight seizures...The typically symptoms (lack of advance, or fixed advance) can be verified with a timing light.

So here we go:
-Engine set at TDC #1 cylinder
-Mark original distributor to block orientation
-Remove distibutor cap and note rotor to red mark on distributor body:


Remove the 8mm rotor bolt and note the "slug with pin" in the top of the distributor shaft. This eventually needs to be removed to service the advance plate. Let's do this now.

Using a small drift, the slug can be removed by tapping under the small locating pin.

The slug removed...

Once the slug is removed, notice the screw down within the rotor shaft. This needs to be removed...and it is easier now, versus later. Holding the distributor shaft from the back side, or locking the star-wheel in place, the screw and washer can be removed.


Discussion Starter · #2 ·
Next, we'll remove the rea

Next, we'll remove the rear cover plate. Although the 512 and BBi model distributors are slightly different than the 365, the procedures are the same. Note: On the 512 distributors, the rear shaft will be splined, versus threaded as on the 365BB.

We need to remove the inner and outer snap rings (and 365 owners need to remove the woodruff key).


Discussion Starter · #3 ·
Now, we ready to get to the gu

Now, we ready to get to the guts of the distributor...and the root of the problem. Turn the distributor over, so the rotor side is facing up. Support the base of the distributor on three blocks of wood, taking care to only support the housing by the ears...and not the rear plate.

Now, protecting the top of the shaft from damage, a firm whack with a small mallet...and the distributor falls thru the housing.

Note: There may be (several) small spacers washers under the star wheel, or on top of the advance assembly shaft...

Discussion Starter · #4 ·
How does this thing wor

How does this thing work and what's the problem. A picture is worth a thousand words, I'm told...

Typically, the advance "arms" seize on the pivots at 3 o'clock and 9 o'clock. This is a direct metal to metal contact area, so if their seized, it can be a bit difficult to remove the weight arms. A bit of heat and penetrating oil usually does the trick.

At 12 o'clock and 6 o'clock are bushing that rarely seized, but do need to slide and rotor within the lower part of the star wheel. Note the wear on this star wheel, as shown below.

Presuming that the weight arms are not seized in the housing, they can simply be removed by pulling up on them.


Discussion Starter · #5 ·
Great care is needed here, as

Great care is needed here, as it's far too easy to switch the placement of the advance springs and pins. The pictures shown below are for reference only, and may not exactly represent your distributor. Mark, or photograph yours before going further...

A careful cleaning, inspection and lube of all moving a replacement of the housing bearings are about all you can do, unless you send the distributor to a specialist (??), as I have never been able to source the internal parts. Due to various wear issues on this particular distributor, it was recently replaced with a new unit.

Regards to all,

Discussion Starter · #6 ·
David: Thanks SO much for you

David: Thanks SO much for your information, and pictures.

I took mine apart. I removed the body, and the back aluminum plate........ended up with the shafts, star-wheel and weights chamber in my hand. The star-wheel shaft was "frozen" onto the inner shaft. I placed the smaller shaft into the lathe, to hold it, while I heated the base of the star-wheel. With some prying, the outer shaft, with the star-wheel, came off. The weights where also frozen in place.

After removing the weights, I cleaned everything. I used some oil for lube......will grease when all is done. The star-wheel now moves about 1/2, as the weights expand. This is compared to only 1/16 movement when I started. I really had NO advance at all......maybe the cause of my problem?

I will now turn the inner shaft (where the star-wheel rides on) on the lathe, and use 1200 grit sandpaper, and finish it off with crocus cloth, to polish it.

I have no wear on the slotted portion of the star-wheel. However, the nylon bushings are cracked......I hope to machine some. With the nylon bushings in place, I wonder how much free play there should be of the outer shaft, before the weights start to move.

I wonder where people, who re-build these things, get their parts. Or, is it easier to just replace the whole unit with new.......that way we all will end up with a spare distributor!!!
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