Using an SC distributor in a 7R case

JohnJL · 10-20-2012, 06:18 PM

I have a freshly-rebuilt SC dizzy and a crappy old 73 dizzy for a 7R mag case. The crank is the original from the 73, initally a 2.4L later fitted for 2.7L euro pistons and cylinders.

I know the SC rotates differently from most others. It looks like they both reach the same depth to engage the intermediate shaft gear.

Is it as simple as switching the gears from the early distributor onto the SC distributor? Will the advance still function properly? Should the rotor be switched also?

Thanks

Gogar · 10-20-2012, 06:24 PM

Remember most (maybe all? Don't quote me) SC distributors don't mechanically advance quite as far as your '73 would. So, even if it fit and you could get it to spin the direction you want, you might not get enough total advance out of it and still be able to have your idle advance proper.

Lukesportsman · 10-20-2012, 06:37 PM

1. +1 on Gogar's advance issue
2. Wouldn't the advance work backward/not at all if spinning inverted? Plus non functional rev limiter. Rotor might be the only thing that works as its timed from external feedback, LOL.
3. SC dizzy refurbished is likely in higher demand than a good 2.7 so you might get a good trade for it.
4. Maybe its not like putting a square in a round hole, but it might be a cylinder when looking for a sphere. It just won't have any of the "rebuilt" part left by the time it works properly.
5. Post in engine building section for more "expert" advise than me

Flat6pac · 10-21-2012, 03:08 AM

You would need to put an SC gear on the crank because reversing the drive on the dist doesnt make anything advance.
Then you need a 6 prong CD and set vacuum from the throttle body for high speed advance.
Sounds like more complications and money then its alternative.
Bruce

BURN-BROS · 10-21-2012, 08:04 AM

Hi John,

The drive gear on the crank would have to be changed.

The dizzy would need to be recurved IF you went to carbs.

6 pin CD box

Tach converted to mag pulse.

BTW, the 3.0 liter distributor is the BEST distibutor Porsche installed in their engines. Very Reliable.

JohnJL · 10-21-2012, 08:19 AM

Thanks guys,

The old dizzy was functioning OK when I took it off the the running motor, but I can feel some play in it when advancing it by hand. I'll take it apart today and have a closer look, it sounds like the better option, and for originality's sake, it is best to rebuild it. It was already recurved for Webers.

The electrical connections arent such a worry, I'vc already put together a bespoke wiring harness on this car. It was running a twic-plugged 3.0 with a JB racing distributor before. I am going to pull the twin MSD boxes and coils and replace with a CD box and blaster 2 coil (with Bosch stickers...)

Aaron, you rebuild distributors dont you?

BURN-BROS · 10-21-2012, 08:31 AM

I do.

Feel free to call or Email.