Ferrari Mailing List: Re: Mageti Marelli S159B Distribtuor Advice Needed

[Hans E. Hansen (FList]

Sure you're not off a spline when you inserted the rotor
shaft into the cam?

Hans.

On Sun, Mar 9, 2008 at 9:36 PM, Robert W. Garven Jr. <rgarven [at] gmail.com> 
wrote:
> Friends,
>
> I am having a problem and I hope one of you can help?
>
> I have a 75 GT4, running standard ignition with only the R1 points. I
> had a coil wire come loose and the car ran on 1 bank for about 30
> seconds so I decided to replace my spark plugs. While I was doing that
> I have a Sun Distributor Machine that I have not had much time trying
> to figure out so I decided to test my distributors. The PO had a
> distributor overhaul and whoever it was that did the work hot rodded
> my distributors leaving in only two advance weights for each unit. The
> car always ran very well so I kept it like that, however the two units
> were so out of spec that I decided to replace them with a set of
> rebuilt distributors I got from TR about 5 years ago, thinking that
> this would solve all my problem and I also wanted to see how the car
> would perform with factory specs. I spent two days checking them and
> learning how to use the Sun ( which was pretty easy) and everything
> seemed fine, they were a little off but within factory specs. They
> were rebuilt very well by a well know expert and the points were all
> centered etc. Even though I had marked everything when I took my
> original distributors off I decide to make double sure I put them on
> right and rolled the engine around to the PM 1-4 for the rear unit and
> PM 5-8 for the front one.
>
> This is where I noticed something weird. The rotor lined up sort of to
> the line up mark but not as close as the units i took off? Below is a
> picture. When I bought them they did not come as a matched set as they
> were supposed to all be rebuilt to the same specs, and I assumed that
> the units were identical. I tried to time the engine but both of the
> distributors seemed to be so far off i could only get a glimpse of my
> timing marks when they were at their extreme rotation. The only
> difference between my units and these are mine had a red label and
> these were silver with red lettering, however both say S159B. What is
> weird is the front set needed to be rotated extremely to the left and
> the rear set to the right so next week I will try to switch them. I
> this does not work I will try to move their weights into my original
> distributors.
>
> What my question is are these splined shafts identical for the front
> and rear distributors or are the different, or could the later one
> have a different spline due to a different camshaft variation due to
> emissions? I have spent 3 days on this so if any can lend a hand I
> would appreciate it. I think they are different, am I overlooking
> something???
>
> One other weird thing, I ordered the spline o-rings from several
> Ferrari parts places and all sent me ones that were so wrong they were
> up to an 1/8" off. I ended up using my old ones but they are worn.
> Does anyone know the correct size of that o-ring? I would try to
> source it but I have only really worn or wrong ones. What is funny I
> bought a set of metric o-rings with 50 sizes a while back and none of
> them are the right size!! Go figure
>
> The last pic is of my original advance weights with notations that
> Mike F. here on the list added. What is weird is the car ran so great,
> always started never stumbled revved to redline and just screamed all
> this with 25 degrees of dwell and these weights?????????
>
> Sincerely,
>
> Rob Garven
>
> pics are here
>
> http://www.ferrarichat.com/forum/showthread.php?p=137531139#post137531139
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