Moto Guzzi Loop Frames - Distributor

Condenser cross-reference

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The condenser has the following part number cross references:

• MG# 12715421
• Magneti Marelli part number 56181103
• Magneti Marelli part number CE 29 D
• Magneti Marelli part number CE 36 E
• Facet part number 0.0613
• Fiat part number 9912723
• Fiat part number 9942107
• Kohler part number 230722-S

  Thanks to Leon Karlak for sending me the information about the Kohler. In Leon's own words:

  I needed to try and get a new condenser for my Eldorado somewhat quickly so, rather that call Joe Eish, I looked at your recommendations. I couldn't find NAPA's equivalent on their web site or anyone elses. The guy helping me do the job said lets use a Kohler condenser that he happened to have on the shelf. It seems like a great substitute. We took the condenser out of the bracket that came with it and turned it upside down in the bracket. Then we drilled a smaller hole in the bracket closer to the condenser and cut of some of the excess bracket off. Then finished by grinding the sharp edge off of the remaining bracket. This may be helpful for others.

The condenser has a Ø of 18 mm, a Length of 31.5 mm, and a µF of 0.25.

Facet part number 0.0613

The condenser was used on the following vehicles:

Similar condensers (same µF) from Facet include the following:

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Condenser wire bolt

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The little bolt that is insulated and serves to connect the electrical wire from the condenser to the points is 5 mm wide x 0.8 mm thread pitch x 22 mm long. Note: the 7 mm nearest the head of the bolt is specially designed to prevent the bolt from rotating within the insulation.

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Contact points cross-reference

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The contact points have the following part number cross references:

• MG# 12715445
• Magneti Marelli part number 71006701
• Niehoff part number WA166
• Facet part number 1.4920
• Fiat part number 9903324
• Fiat part number 9909413
• Fiat part number 9911552

Facet part number 1.4920

The contact points were used on the following vehicles:

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Distributor ball bearing

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There is a tiny little spring loaded ball bearing used to make contact between the advance plate shaft and the main shaft that is connected to the gear. The size of this ball bearing is 3.175 mm or 0.125" or 1/8".

A suitable replacement is available from McMaster-Carr. Search for part number 9528K11.

If you need one, let me know as I've got plenty. greg>at<thisoldtractor.com

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Distributor cap cross-reference

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Thanks to John Cowart from Lakeland, Florida for providing me with this information.

The distributor cap has the following part number cross references:

• MG# 12715432
• Magneti Marelli part number 71037202
• Facet part number 2.8163
• Fiat part number 9910469
• Fiat part number 9911820 (1)
• Fiat part number 9991820 (1)

The distributor cap was used on the following vehicles:

• 1960-1965 Fiat 500 Giardiniera (9911820)

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Distributor cap securing screws

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The two shoulder screws that screw into the points-plate and whose shoulders serve as a pivot for the spring wires that secure the distributor cap are 4 mm wide x 0.7 mm thread pitch x 13 mm long. Note: the 5 mm nearest the head of the screw is the shoulder; the remaining 8 mm is threaded.

A suitable replacement is available from McMaster-Carr. Search for part number 90270A657.

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Distributor clamp improvement

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I extracted this information from Patrick Hayes off of his own website after he made notice of it on the Yahoo! Loopframe_Guzzi news group. In Patrick's own words:

The Problem:

The single point Magnetti-Marelli distributor used on the loopframe Moto Guzzi has a minor nuisance fault. When the spark timing is set, a pinch bolt is tightened to hold the distributor in fixed position. If secured with a little too much force, the pinch bolt head and its support washer can gradually become somewhat embedded into the machined surface of the adjustment arc on the distributor body and form a surface crater in the casting. The distributor body is cast from a very soft alloy. When you next try to set the ignition timing, the pinch bolt and this subsequent crater have a 'mated' relationship. Unless the pinch bolt is loosened completely, the distributor body can not rotate easily for adjustment. When the pinch bolt is re-tightened, it has a tendency to ramp the distributor back into the old position rather than the required new position. This is a picture of a 'mildly cratered' adjustment arc on the distributor body.

The Solution:

I have fabricated a clamping piece to improve the load distribution of the pinch bolt and help alleviate the tendency of the adjustment arc on the distributor body to become cratered. The clamp piece is fabricated from stainless steel, so no additional finish is required. The material is 2.4 mm thick so it is not likely to bend or distort at all under the clamping stress. The clamping piece will lift the pinch bolt head by this 2.4 mm thickness dimension, so you will need to fit a longer screw. I recommend a stainless steel Allen head cap screw, 6 mm diameter by 1.0mm pitch by 25 mm length below the head. Using a screw of insufficient length presents an increased risk of stripping threads from the cast distributor base.

What YOU have to do:

Source a new screw. Don't use the original. It is already not long enough to utilize the full thread available in the lower body. Now the head will be lifted by 2.4 mm. A new screw at 25 mm below the head would be best. I suggest an Allen head screw. It will be easier to access using a ball-end "T" handle wrench for easier clamping.

You need to determine how badly your own distributor clamp area has been cratered and what to do about it. It is possible that you may be able to just install this clamp plate and be done. If the distributor arc is badly cratered, then consider removing it and carefully hand filing the upper surface so that it presents a single, smooth surface for the clamp to slide. If at all possible, I highly recommend that you find someone with a lathe and use that to cut the cratering from the upper surface. Using a lathe will ensure that the cut surface is now true and perpendicular to the axis of the distributor shaft. Search your neighborhood for a lathe. The most basic lathe setup should be able to do this cut in a minute. Below is the result of a lathe-cut surface. This is the same distributor body whose crater is shown above. Three-fourths of a millimeter had to be cut away to remove all trace of the clamping crater.

You are welcome to mail your distributor to me for this lathe service, but that isn't really practical. Hopefully you can find someone local and ask for their help.

Here is the final product installed. It helps to use a "wavy" washer under the screw head so that you have a little residual spring pressure on the clamp when you are adjusting the distributor. I'll include a wavy washer for you in the mail.

The Cost:

I'm not in the fabrication business. I do little tasks like this just out of curiosity and to help the Guzzi community. I do have to buy the metal stock material. I have invested in a lot of tools. There is a substantial time element to push these out. Charlie Mullendore of Antietam Classic Cycle generously donated the distributor body template, added some design opinions, and tested the first production units. I think these are certainly worth the equivalent of a favorite local brew. Its not practical to mail a can of beer and I can't wait until we meet at some rally. What I would like YOU to do is to pledge an equivalent donation value ($5 seems about right) to your favorite charitable cause. Buy some Girl Scout cookies. Put a FIN into the bell-ringer's kettle. Buy a bat for your local Little League team. You don't need to tell me what you do for a donation. There is no one, other than your own internal moral compass, to check up on you to assure you have followed through with the donation. Provide your postal address and I will post one of these off for your machine. I had the stock to produce about 50. I still have to cover the postage to you. I doubt I will make any more of these. Please don't ask for one unless you think it represents a functional improvement to your motorbike.

Patrick Hayes
Fremont CA
pehayes at comcast dot net

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Distributor drive gear pin removal

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Thanks to Charlie Mullendore of Antietam Classic Cycle for providing me his methodology in a private communication.

The pin thate holds the distributor drive gear in place can be extremely difficult to remove. Charlie shares his methodolody:

Just removed two pins very easily last week doing this same exact swap. Here's what works for me:

1. grind the peened head off one end.
2. tap the pin in from the other end with a hammer and punch (helps you to see the pin on the ground end for the next step).
3. centerpunch the pin and drill the remaining head off (I used a 3/16" bit IIRC). You don't need to drill very deep, more a countersink.
4. using a good quality 1/8" punch, drive the pin out.

Reinstallation is very easy, tap the pin in and peen both ends. Here's a few shots of the crude fixture I made for the job out of 3/8" thick steel.

Fixture to support distributor during removal of the drive gear.Fixture to support distributor during removal of the drive gear.

Fixture to support distributor during removal of the drive gear.Fixture to support distributor during removal of the drive gear.

Fixture to support distributor during removal of the drive gear.Fixture to support distributor during removal of the drive gear.

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Distributor rotation (advance vs. retard)

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The rotor under the distributor cap rotates clockwise.

To retard the timing: Rotate the distributor body clockwise.

To advance the timing: Rotate the distributor body counterclockwise.

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Distributor rotor cross-reference

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The distributor rotor has the following part number cross references:

• MG# 12715431
• Magneti Marelli part number 70189503
• Facet part number 3.8252

The distributor rotor was used on the following vehicles:

• 1960-1965 Fiat 500 Giardiniera

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Distributor shaft o-ring size

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The size of the o-ring used to seal the distributor shaft inside the distributor body is 17 mm ID x 2 mm Thick. Viton o-rings are best, but Buna-N will also work and are a lot cheaper. Make sure to purchase an o-ring that is sufficiently soft...something with a Shore A Hardness rating = 70 is great.

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Distributor spring

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There is a tiny little spring that pushes on the tiny little ball bearing that is used to make contact between the advance plate shaft and the main shaft that is connected to the gear. The size of this spring is 3 mm OD, 5 mm long uncompressed, 0.3 mm wire thickness.

A suitable replacement is available from McMaster-Carr. Search for part number 9435K11.

If you need one, let me know as I've got a few extras. greg>at<thisoldtractor.com

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Ignition contact points cross-reference

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• O'Reilly Auto Parts part number A512, Borg Warner (1950 - 1977 Fiat)
• Checker Auto Parts part number A512, Borg Warner (1962 FIAT 600D L4 0.8 Liter Carbureted - 47 CID)

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Points-plate and condenser screw

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The little screw that secures the points-plate and condenser to the distributor body is 4 mm wide x 0.7 mm thread pitch x 8 mm long.

A suitable replacement is available from McMaster-Carr. Search for part number 91292A108.

If you need one, let me know as I've got plenty. greg>at<thisoldtractor.com

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Points to points-plate hold-down screw

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The little screw that secures the points to the points-plate is 3.5 mm wide x 0.6 mm thread pitch x 4 mm long.

A suitable replacement is available from McMaster-Carr. Search for part number 91800A175.

If you need one, let me know as I've got plenty. greg>at<thisoldtractor.com

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Spark plug cap replacement

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NGK makes a very suitable replacement spark plug cap. Look for Stock Number LB05F (8051).

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