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PostPosted: Sun Oct 21, 2018 9:29 pm 
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I have attached some pictures of a 4 cam distributor. The housing bears the descriptor VJS4L2 and is date stamped 7N. The distributor has a drive coupling mounted with a 5mm pin. The drive coupling is similar to the BR types [offset driving lug]. The cam lobe assembly has a CCW arrow and the plate is pinned at the L indicating it turns CCW in the application mode. I would like to know the engine application. There is no groove for a seal or gear drive so no V drive application. Is this a cam drive application?

Is there a reference somewhere to the specifications like the advance curve? An exploded view of the distributor will help as well. Most of this stuff is still held close to the vest, so I am taking a flyer on this request.

I have also attached pictures of the rotor which is beat up and chipped in several places, Looks bad, is out of balance but would probably work in a pinch. It had a Petronix unit fit--very poorly I might add and is without a condenser. There is a protuberance on the housing which embodies a bore where the capacitor was mounted. Are these still available? source?

I am trying to return it to its original configuration so I have included a picture of the point set mounted to the fixed plate. Looking for these also and the source.

It does not have an identification plate either. Is any one making these? Would someone post a picture of one showing the rivets. please or cite a link for same. I cannot seem to come up with the correct "key words" on searching on the net--for any of this stuff..

This distributor had a wobble in the advance cam assembly so severe that the advance spring cam was clipping the top of the mounting post for the advance weights. There is a little bushing in the assembly that must have been fabricated from the same material used in the early valve guides. Poor selection for the latter although ii was easily broached to size. The Factory made 4 sizes, 2 in a set for 8, 9, 10 and 11 mm. I have them all, some never used. Anyone interested?

Any info greatly appreciated.

Addendum by edit on 31 October 2018 below.

Delete the bold text above as it is not correct. Ignore the italicized text above as it is not relevant.

It was later discovered at the machine shop that the advance cam assembly body is a monolithic construction and that the bore of same embodies an undercut for oil accumulation and likely spread by an elongated figure 8 pattern machined into the distributor shaft interface which would carry oil to the bearing surfaces. The "bearing" surfaces to be serviced by the oil only have an arc movement of 10-12 degrees, but were worn a measured .021 inch. Seems like a hefty amount unless no oil was actually transferred by the design feature provided. Provision for an oil supply evaded visual confirmation unless you were to remove the rotor [arrested with a screw], squirt some oil in the cavity exposed, and replace the rotor. There was no felt washer in these distributors and apparently no room to install one. Is this correct? And how does oil get renewed to the surfaces?

This assembly was repaired, the distributor reassembled and tested; all published parameters on page 94 of the little spec book were found to be in compliance.


Attachments:
4 cam pts on mounting plate.jpg
4 cam pts on mounting plate.jpg [ 1.2 MiB | Viewed 509 times ]
VJS4l2 distributor, top view.jpg
VJS4l2 distributor, top view.jpg [ 136.69 KiB | Viewed 509 times ]
4 cam distributor VJS4l2 date stamp 7N.jpg
4 cam distributor VJS4l2 date stamp 7N.jpg [ 150.62 KiB | Viewed 509 times ]
4 cam rotor showing mounting hole.jpg
4 cam rotor showing mounting hole.jpg [ 169.89 KiB | Viewed 517 times ]
4 cam rotor.jpg
4 cam rotor.jpg [ 122.12 KiB | Viewed 517 times ]
4 cam coupling, 5 mm pin.jpg
4 cam coupling, 5 mm pin.jpg [ 1.07 MiB | Viewed 517 times ]

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Last edited by Albert Tiedemann on Wed Oct 31, 2018 2:02 pm, edited 1 time in total.
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PostPosted: Mon Oct 22, 2018 2:28 am 
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Hi Ab,

7N = July 1957. Carrera distributor, cam mounted, most likely 550 spyder but possibly a street car motor. The factory was converting to the 60 degree crank driven V drive about then.

Jacques Le Friant, Jeff Adams or others will tell you for sure.

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PostPosted: Mon Oct 22, 2018 3:16 am 
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Ab,

The distributor you show is for a cam drive 4-cam street car. The L denotes left hand rotation while the Spyders used right hand rotation distributors, the VJS4R2.

These distributors did not use a data plate, the earlier ones without the pressed in condenser did. I am sorry but can not help you with advance specs. I am sure Jacques and Jeff might be able to do so.

I tried for some time to have the points done but gave up in the end. Word on the street is that Peter Hofmann had them done recently. I have several NOS sets for my on use so am reluctant to give those up.

Hope this helps a bit. I am sure Jacques and Jeff with their experience can add more.

J.

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PostPosted: Mon Oct 22, 2018 7:50 pm 
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Hi Ab
if those are Swatta's I sent him some NOS suppression rotors so he could listen to his radio. the only specs I have are on page 94 of the spec book last column. and NOS points. and a set of Joris' caps.
j

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PostPosted: Thu Oct 25, 2018 5:24 pm 
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Those are for the Carrera 1500 motor in the 356A. Porsche part number 547.09.226.1

I was lucky enough to find a pair of NOS capacitors for my VJS 4L2 distributors - they were Bosch part number ZV 2/3512. They are a real bitch to remove and install - you basically destroy the old ones when removing them and then you have to measure the bores in the distributors. I had to hone mine up a couple of thousandths to get the new capacitors to fit. I found the capacitors on Ebay - paid around $50 for the pair. Porsche part number 692.602.230.00

I have a really rare pair of Mallory dual point distributors in CCW (left hand) rotation that were fitted to the original 547 motor that I bought back in 1973.
It had been stuffed into a 912 so the previous owner had found a pair of reverse rotation Mallory distributors to use in that application.

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PostPosted: Wed Oct 31, 2018 2:22 pm 
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Please see the initial, edited post.

In addition, I seek answers to a few more questions.

I have posted a picture of the driven coupling that was installed on one of the two distributors received for "fixin". When the rotor is aligned with the mark on the distributor housing,the offset on this coupling favors the bore for the capacitor. On the other distributor, the offset has been installed 180 degrees opposite. Which is correct?

And the capacitor that is "pressed" into the bore? It has been reported that the original capacitor is a really tight fit and that several thousandths of an inch were honed to make it a reasonable fit. Why so bloody tight? Actual measurements of a NOS capacitor and the housing bore would place it in the shrink fit class. I am not sure just how much the capacitor can be compressed before fracture in the bore as the original looks like it was hand made [packed and soldered shut with a very heavy wire lead]. What is the capacitance spec on these? I have heard/learned vicariously that the capacitor used with the 022 distributor works well--and perhaps better than a NOS one for this distributor.. Measured the diameter of a few of the real ones [...067] and found that these would be a bear to install in the existing cavity as well. Comments?


Attachments:
Coupling Offset, Carrera.jpg
Coupling Offset, Carrera.jpg [ 381.71 KiB | Viewed 276 times ]

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PostPosted: Fri Nov 02, 2018 6:48 pm 
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Hi Ab
You have a 50/50 chance of getting it right and if you miss the installer can easily rectify the error. Now for your edification the drive piece that is at the end of the camshaft can be installed on one side of the camshaft either sharing the keyway for the lobe if so the slot is perpendicular to that axis and the narrow end. if opposite the cam lobe is used as a nut on the other side the orientation s random. the axis of the valves is 39 degrees from horizontal and the intake lobe center is 110 from TDC.
j

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PostPosted: Sun Nov 04, 2018 11:33 pm 
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The cam driven distributors are often quite worn, with many of the internal advance mechanism parts taking a beating. Porsche must have recognized this early on, as the crankshaft driven V drive setup came out in 1956 - 57 with the 550A engines.

The first service bulletin ever issued for anything 4 cam related was about the cam driven distributors. The bulletin states to send the distributors back to Bosch for inspection on a regular basis. I haven't tried to contact Bosch, but pretty sure they aren't offering this service anymore!!

Interesting to note it says to do this "if used for racing purposes". I think the wear is probably worse when engines are used for ordinary street use, as the advance mechanism would be more actively used at lower revs than in a race car where it is usually at full advance.

Gerry McCarthy drew up the advance curve graph many years ago, and I refer to it quite often. Note that the right side should say " Degrees of advance"

I don't think the press fit of the condensors in the later distributors was very precise. The 067 from a regular pushrod distributor should fit and work fine.


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4 cam distributor info.pdf [658.74 KiB]
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PostPosted: Mon Nov 05, 2018 1:03 pm 
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this might help


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thumbnail_DSC_0044.jpg
thumbnail_DSC_0044.jpg [ 209.85 KiB | Viewed 124 times ]
DSC_0045.JPG
DSC_0045.JPG [ 384.63 KiB | Viewed 124 times ]

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PostPosted: Tue Nov 06, 2018 4:55 am 
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Hi Jacques
Where can I get the Blue Print 4 Cam engine drawings, shown above from ?
Would just like them on my garage walls!
Kind regards Jay

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PostPosted: Tue Nov 06, 2018 12:15 pm 
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Hi John
it is taken from the Carrera Guide page 176 I think the reason for this Fig was to illustrate the change from 95mm to 96mm for the spigot.
j

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