Recommend a distributor expert

Hi 335S, sorry i was just joking about the other tools. Also i did not explain the need for long pins very well.
I guess I have opened up enough Marelli, to find the pins in service, inside the brass/bronze flyweights, because they were too short, have wallowed a large cavity at their tails and now cause the weight to hang up and not allow full travel, or the pin to go out of alignment causing a skewed advance curve. So pin length determined by the distributor worker would be a big advantage. Choosing 2 lengths that fit a specific distributor would not be a good idea, IMHO. To fit Marelli S85, S125, S127, S129, S158, S159, and all the variations of these models would take a lot of different pin lengths.

Your help on this is fantastic, as we find no one else has had the resources to pursue this small detail.

Do you have a draft of a print on this pin that we all could look at and compare to the pins we may have available? Then that feedback can be compiled for your use to be sure everyone is desiring the same thing. anyone have a dimension drawing we can compare? or just dimensions from existing pins?
thanks for all help
Craig
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I guess I would agree, you could probably just make all long pins and everyone can trim the length to suit thier application. I would be interested, so far I would need enough to do four distributors, so thats what, 16 pins? I dont know what your looking at for a final cost, but let me know. I'm pretty sure a CAD machine can spit out a bunch a lot faster than me with my old 10" Logan. What about the future, how long will they last, will I still own a Ferrari 20 years from now, and if I buy extras, will I even be able to find them again when I want them?

So lets see. Weights are available at GT Parts? New points cams are available from Superformance. Wow, with a lil here and a lil there, we could have virtually brand new distributors. Now all we need is a cap and rotor that dont cost a fortune. Sorry, but I wont stick anything GM on my car. I want it to look like a Ferrari as much as possible, right down to the caps.

 

This might work for me. I am not familiar with specs on surface finish, nor calling out common shop steel for this type fab work, but here is sketch.
How about some feedback on the sizing and what you may have in hand from your Marelli ?
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if anyone has a Marelli apart, it sure would be nice to get some pin dimensions from you along with the model Marelli. please see what you can do for this effort, thanks

 

I have a few in a bag in the back room from early 308's. I'll try to dig them out and see what I find.

 

This would be a great help Artvonne, thank you.
Craig

 

Great thread guys . Now that we see an of the shelf V-8 cap will fit has anyone found a 4 cyl cap the fits the same way? Keep it going here

 

Great thread! I, too, have played around with these, and I have a Sun 504 distributor machine that I purchased just to set up and keep my distributors in "tune". I also have managed to "collect" a few bits and pieces, but I do not claim to be an expert. I had an adapter made to bolt the distributors to, and the base of it fits in the "jaws" of the distributor machine so as not to damage the distributor in any way. I adapted a steel rod with a piece of rubber hose to connect to the splined distributor drive to avoid damage and still get the distributor to turn. As has been stated before, if you are satisfied with the technology of points and mechanical advance, these work ok and provide a smooth, if not absolutely accurate advance curve when properly adjusted. For my purposes, I am totally satisfied with these "relics" and enjoy making them do what they were designed for. The Sun measures everything needed to ensure success, and I have found that if the advance moves smoothly through the entire range and actually comes in full at the lowest specified RPM, that these things really work well! Most of the problems I have seen relate to dirt or lack of lube in the weight/spring/pin areas. If you run out of resources, I am willing to help (through a PM) to any FC member.

 

Hey I have a distributor question. My 86 3.2mondi's distributor wires are a little beat up and i wanted to replace them. Do you recommend going with NOS wires or someone else?

TIA

Nate

 

Hi Ron, thanks for the photo and drawing of your pins. It would seem that comparing dimensions shows the pins to be of same dimension with only the length being varied. The pins should have a chamfer as you show, when their dimension is reached.
So can we get a Fchatter to fab a hundred of these with 25mm length?

Lube for this advance mechanism has been discussed and i cant remember all the recommendations, but i believe one lubricant was a Bosch distributor lube specifically for advance mechanicals of this type.

 

Well, I appologise, I have such a pile of boxes of parts between the two cars and stuff I have collected as spares I am having trouble locating my "ignition" box. I guess there are worse things in life than having boxes of Ferrari parts.

 

I'm coming late to this thread but might I suggest the following thread

http://www.ferrarichat.com/forum/showthread.php?t=149633

There are other threads out there as well that cover these topics.

This one covers Craig and my efforts to convert my Lamborghini with a single distributor/dual coils/4 sets of points to a Pertronix system.
I went through all of these issues but mine was not in as bad shape.

Rob a.k.a. MOKU was of enormous help to me as were many others. Rob has done a lot of these conversions and servicing of the advance mechanisms so if you want an expert
you might contact him and send the thing to him. He also has an electronic replacement for the advance mechanism and in that case he just freezes the mechanical system with extremely stiff springs. The electronic boxes are very small and easily hidden. Just a thought if your mechanical system is a mess. He did indicate that getting and keeping the mechanical systems properly setup was a real *****.

In my case Craig and I figured everything out and Craig was nice enough to do the final sensor alignment for me.
It looks totally stock and used a Jag cap & rotor. Obviously, the dual distributor 308's are a slightly different situation.
A number of people have converted these to Pertronix and utilized the advance mechanism of a single distributor to perform all of the advance function and just let the second distributor act a high voltage ignition delivery device with no advance function.

Hope that helps.

Bob S.

 

Yes-Bosch distributor lube is the stuff to use-in moderation. A good case of "less is more".

 

whoops! DUH, I should have searched that way instead. Thanks!

 

Great discussion on Marelli pins. Can anyone help with the material spec on these pins to be fabricated? Should it be 4140 that might be fine as is or could be heat treated for hardness? Or another material? How and what do you call out on a blueprint for surface finish of this type of pin? Should there be a concern about heat treating the pins to a medium or high hardness to improve their lifespan.
What type of of hardness checker would you use to detemine the hardness of a pin as small as these? and where on the pin would you set up to check hardness?

any help on this will get us closer to fabricating these missing links.
any help on springs and spring cups would be great as well!
Craig
the Bosch lube is available at many German car websites.
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interesting

 

Hi All,

As Bob S. suggested in his earlier post, I've been messing around with these things for quite some time and have a bit of insight for those still interested...

I guess there are several different ways to attack the continual problem of pin and drum wear in these distributors. I've tried many different methods over time, all with varying success. The problem here is more the design itself than the materials, techniques, or lubricants used to assemble them. Most, if not all, of the methods I have employed have resulted in a greater life span but none have served to eliminate the problem in its entirety. Yes, pins can be made with very little effort that will outlast the originals. You can spit these things out of an old school Swiss screw machine at the rate of several thousand a day with very little setup time. A reasonable CNC lathe can do the same at probably double the rate. But you still haven’t solved the problem. Sooner or later you’ll end up with the same condition at either the pin or drum.

The real issue is that of the actual contact area that the pin presents to the drum as well as the motion it describes against the ID of the drum while running through the advance curve. As you would imagine, the contact patch on a new or freshly dressed pin is *extremely* small and must withstand very high loading. We’re talking an area of several thousandths of a square inch at best. Your ability to properly lubricate that tiny little area for anything other than the first few minutes of operation is damn near zero. Regardless of what type or quality lubricant you choose. Hence, wear begins almost immediately. This can be either at the pin or drum depending on which you got harder. I’ve had many examples where I have run in a distributor on the car for well less than a few miles and then pulled it to put back in the machine for further testing. In all cases the pin or drum had already begun to show wear. Some were dramatic. That tells me something needs to be fixed if I want my work to last...

Again, two issues need to be resolved for this to really be successful. First you must do whatever possible to increase the contact area on the pin. A larger contact patch will directly serve to reduce the point load experienced at the drum. Less load will obviously reduce the tendency for both to wear. I have tried several methods here of which one has worked well. This method entails ditching the full radius on the pin altogether and moving to a flat radius that’s machined to match the radius of the drum. Something akin to a ramp. This presents a *huge* increase in available contact area and comes close to eliminating the wear problem. The only drawback with this design is that the pins tend to rotate in their respective bores and must be carefully tailored so as to not allow them to lose contact with the drum at any point. It’s not that much of a hassle and proper spring choice helps greatly.

The second issue concerns the arc the pins move through while achieving advance. It’s a really weird movement and is one that induces more a tendency to scrape than to slide. Your options in achieving resolution here are very limited. In fact, I’ve only come up with one design that might possibly eliminate this condition but have yet to find the time to fabricate and test it. This idea removes the pins completely and replaces the spring barrel with something very similar to a roller lifter. The end of the barrel is machined into a yoke that supports a small bearing or hardened roller. The interior of the barrel still retains the spring. Again, I haven’t had a chance to really look at this one yet. It does look good in that it will accommodate a larger contact area in addition to eliminating the scraping movement of the pin against the drum. If anyone’s interested in taking this idea further I would be more than willing to provide whatever assistance needed to get it off the ground. I just can’t take the lead role time wise.

If staying with the original pin design, I would strongly suggest that you use the highest quality EP moly based sticky stuff you can find. I base this on my experience and comments above regarding the available contact area on these pins. I’m not bashing the Bosch lubes, I just don’t feel they’re appropriate for this particular application.

Comments and questions more than welcome.

Rob Stewart

 

Great discussion on Marelli pins. Can anyone help with the material spec on these pins to be fabricated? Should it be 4140 that might be fine as is or could be heat treated for hardness? Or another material? How and what do you call out on a blueprint for surface finish of this type of pin? Should there be a concern about heat treating the pins to a medium or high hardness to improve their lifespan.
What type of of hardness checker would you use to detemine the hardness of a pin as small as these? and where on the pin would you set up to check hardness?
any help on this will get us closer to fabricating these missing links.

Rob, Thanks for your great ideas. What lube grease exactly are recommending? i thought the Bosch distributor lube was sticky moly lube.

Also everybody, what quantity of lube grease should be used? i see far too many Marelli advance mechanisms with no lube at all, clean but worn out. I also think the Ferrari upright vertical configuration holds the advance lube in the drum while the Lambo and Ferrari horizontal mounted Marelli tend to throw it out much more quickly, requiring more frequent service.
Craig

 

Hi Craig,

Sorry to have not responded. Been busy with one of the cars all weekend and am just now home. Let me think about your questions and I'll post up in the morning.

Rob

 

Hi Rob, I think just a good spec for the oem pins would be great. We could get quotes and someone to fab.
springs and sleeves could be next!

I enjoyed your thoughfulness on this - the wedge pins or roller pins could be great. I think some might choose to pre wedge their pins if they thought it was better for long term performance. I am thinking that simply a source of oem pins would be a great maintenance resource for all the 50's, 60's and 70's era Marelli - Dinosaur spark.

I am hoping Fchat has enough engineer or machinist participation to make this an easy task, but it is not looking like that is happening.

Lots of lookers but aint nobody saying nutin.
Craig

 

You need a distributor expert? Here you go!

I found this picture today in an old Italian magazine.
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Jeff,

I'm laughing my tail off! That picture is great!

Any chance I can get a high res scan of that? There are a few people, including myself, that would *kill* to have that framed on the wall next to our 504's!

Rob Stewart