Fitting 12 plug cap to 6 plug distributor
 

I have bought a twin plug setup for my RS replica which has:

bosch 12 plug cap
bosch twin rotor
machined base plate
2.7 Carrera bosch distributor

The original (6 plug) cap can only fit on the dist'r at one (two?) positions governed by lining up the slots/tabs/clips etc.

However, the base plate can be positioned anywhere and then locked down with the grub screws. The parts were all assembled and had been removed from a running car when i bought them and seem to work fine.

However, I was wondering how I check that the base plate (and thus the 12 plug cap) is positioned correctly relative to the dist'r.

Also, we have had some adjustment issues with the underside of the dist'r fouling against the case fitting for the oil line for the pressure fed tensioners. I've seen some setups where the oil line appears to run from the rear of the case - any other ideas?

Ryan:

The RSR cap has a small roll pin that should locate it in place on the adapter ring so after its been phased for proper rotor positioning, it will remain so.

We use a distributor machine to set everything up and I have a special RSR cap without a top so I can watch the rotor tips and then index the cap position so the tips of the rotor match up with reluctor position for correct ignition firing and performance.

This ensures that the tips of the rotor line up with the contacts inside the cap at the right time and prevents the cap contacts from excessive arcing.

In many respects, the Bosch RSR cap is superior to the (cheaper) Marelli one due to its wider spacing of the plug terminals that minimizes cross-firing with high-energy ignitions. :)

I use a special, slightly longer oil line behind the distributor for clearance, but one can reshape the existing one a little bit if you are VERY careful.

Steve,

Thanks for the prompt reply.

My cap also has the roll pin which mates with the adapter. In relation aligning the tips of the rotor with the reluctor position - are we aiming to centre the rotor tips with the contacts when the points are fully open?

It looks like we are on the right track with the clearance issue as we replaced the hard line with flexible braided hose - but we are still having a little fouling issue where it end connector enters the case. I might try and source a smaller or angled connector.

ps. Thanks again - the beer's on me should you ever find yourself downunder?

Hi Ryan:

First question,....Are you using a point-type distributor????

If so, I'd heartily recommend that you either convert that to breakerless with a Pertronix, or use a '76 Turbo distributor which is breakerless and will work with your RSR cap adapter,...:)

One of these days I'm going to visit Oz and I'll be looking up a bunch of Porsche people,...:) Thanks for your kind offer.

steve,

yes, i'm still using points. I bought a petronix when i was still running single plug but they supplied me the wrong one. i tried for months and months to return/exchange etc but the local distributor down here sucks...

what details from my dist'r would you need to source the correct one for me?

i visit the usa for work about once a year - the flight's not too bad.

You should use the Pertronix # 1867.

Fits like the proverbial glove. :)

If you cannot find one, e-mail me directly.

thanks steve - will do