Bosch Distributor Mechanical Advance Limiting Screws

['76mintgrün'02]

10 minutes ago, John76 said:

Don't use this to "tuna" distributor, or it will "flounder" ?

 

What are you putting in your coffee, John?     That grease held up nicely on my odometer gears, so I used it again for the most recent repair.  Sil-Glyde is rated for heat up to 425 degrees (F).

 

7 minutes ago, Lorin said:

Time to hoard , I mean collect more spares !

 

 I agree.  I operate on a limited budget though.  Around four months ago there was an eBay listing with maybe eighty Bosch distributors that sold with only two bids.  The winner got them for $50, plus $130 shipping.  I'm not sure how I'll avoid forever regretting not getting in on that auction.  

 

Tom

['76mintgrün'02]

My NOS points arrived today, right on time and very well packed; so I left some nice feedback for the seller.  Then I opened the packages and both sets have obvious water damage.  NOS = Nasty Old Stock.  Dammit.

 

 

The listing says they have more than ten sets available, so I just sent the seller a message, asking if they've all been damaged in this way.  My guess is I'll be sending them back for a refund and buying New New Stock points.

 

The ones I filed seem to be working just fine and the car's running very smooothly again.  I don't want to go to the trouble of modifying/installing cRusty points, but will follow through with new in the near future.

['76mintgrün'02]

It turns out they cleaned up okay.  I scraped the crusties off with a pocket knife and then closed them on a grey scotch brite pad and pulled it through a few times.  They'll be fine after all.

 

 

I need to make a couple of little tabs to weld onto them, with holes for the adjustment screw to run through.  It'd be nice if the adjuster accepted new points without having to do that step, but I can't see a way to make that work.  It's only two tiny tack welds though, so it's not a big deal.

 

I'll send another note to the seller, saying no need for a refund. 

Tom

['76mintgrün'02]

Last night I pulled the distributor and modified a new set of points for the adjuster.  The old ones had already developed a little booger on the anvil side of the contacts.  I read on another forum that once they start to erode in that way, they'll do it again shortly, (when they're cleaned up/filed).

 

I think the crusty looking rust on the NOS points is from flux that was used to braze the contacts on and solder the wire (plus a little moisture).  That's what it looks like anyway.  I'm just glad they cleaned up okay.

 

There are a few steps involved in making them fit the adjuster.  Welding the stainless steel tab to the anvil side just requires a few tiny tack welds; but it is a bit fussy to get it aligned and clamped up tight.  Needle nosed viSe grips worked well.  The welds need to happen quickly to keep from cooking the points.  They're not beautiful welds, but I pulled it off.

 

The wire on the points I removed was a little longer than the new ones, so I had to replace the wire in order to reach the condenser's tab.  (The wire length and orientation varies on Bosch points).  The wire I removed had super fine strands inside.  

 

 

I used a piece of mint green wire from an old set of VW points (they have a very long wire) and made it come off the points in the opposite direction to keep it out of the way of the Allen wrench.  The strands of copper in this wire are not as fine, but it is a nice heavy wire, compared to some.

 

 

 

The wire's attachment to the points and spade connector both come off in opposite directions now.  The original wire was crimped twice.  Once to the wire itself and once to the insulation.  The insulation crimp is what grabs the wire now.  The original wire crimp breaks when you open it up, so I used pieces of stainless steel wire (fishing leader wire from my Grandpa) to tie the wire in place.  That's the most fun part.  It's the same wire I use as filler rod for the tack welds.

 

 

Raising the points up an eighth of an inch makes them hit the points plate's attachment to the housing, so they require a little grinding to get clearance.  (I'd forgotten about that step).  I taped them up to keep the grinding grit out and removed the bit that's marked with a sharpie.

 

 

Another clearance issue comes up where the back of the adjuster approaches the condenser's connector (due to vacuum advance), but there's just enough room if you bend it out of the way.  It's really tight in there.

 

I put the distributor on the Sun machine and set the dwell to 60.  Then I connected the vacuum pump to make sure everything clears when it's pulled on.  Clearance was not an issue, but I did notice that the dwell angle increases by two degrees as the points plate rotates (six degrees).  Increased dwell means decreased advance, since the points are opening later.  I guess that means my advance pod is only giving eight degrees of advance, instead of twelve (since the numbers double at the crank).

 

The good news is that the weird timing fluctuation at low rpm (mentioned in a post above) doesn't happen with these points.  I'm glad I didn't spend time trying to fix it with the old ones.

 

Tom

[JohnS]

I've had good luck using IKAR brand points that I've found on ebay.  I guess they were the vintage points brand sold for Mercedes cars back in the day.  Made in West Germany, really good quality if you can find the ones that fit for your distributor.  The ones I bought are ventilated (they have a hole where the points make contact with each other).  

 

This is just a random link that I found on ebay searching today, don't know whether they fit your application or not, but IKAR is a good brand.  Search and ye shall find...

 

Vintage Mercedes Ignition Points, 000 158 35 90

WWW.EBAY.COM

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Only fits certain years and models, double check this is the correct set of points.

 

 

Edited August 29, 2022 by JohnS

['76mintgrün'02]

Cool.  Thanks, John.  I had a set of points with donut style contacts, but I don't remember the brand or application.  It wasn't that brand though.

 

While installing the distributor with a fresh O-ring, I had trouble getting the ring into the housing (again), so I stuffed a rag in the hole and knocked the edge off of the opening with a piece of sand paper.  It didn't take much to dull that sharp edge and now it slips in very easily.

 

 

I wiped the hole clean with another rag and then spun the other one out, to make sure not grittiness got in.

 

I placed a piece of tape above the distributor and marked the positions of the clamps, as well as an arrow to indicate rotor position.  That makes it super easy to put back.  

 

 

Tom