1975 Carrera 2.7 MFI

[dragonfly]

That’s a great car and some stunning photos. Thanks for sharing and enjoy the experience.

As Mike says, I vividly remember my first decent drive of an MFI car, the ex-Girolex RS in which Tony Dron had recently won the PCGB Championship

[brembo]

Think I saw this one up for auction before restoration.Can't remember how much it sold for.
https://www.thesupercarrooms.co.uk/car- ... r-sale-NWP

[Tp81]

Tonight was a proper run, 120 miles or so. Porsche Perth launch of the new 911.

Dry on the way up from Glasgow, pissing down and dark on the way home.

Things on the list: new wiper blades, new LED bulbs for the headlights. Vision with two candles in the rain was not great.

The car was faultless for the majority of the run up, good properly fast stretches it felt stable and strong. I did see the occasional puff of smoke under hard acceleration, the run at the later stages is all 70 mph with speed cameras, sitting like this for 15 mins I started to fell the engine miss, just slight pause in power and then continued on. Some cause for concern but as soon as it started I was leaving the motorway and it was fine driving to the car at lower speeds.

I asked one of my friends to follow me all the way home just in case, the majority of the run home the car was fine, then when we were almost off the motorway some really bad jolts through the car, engine missing and backfired a couple of times. I coasted the last stretch off the motorway, the car was really struggling and juddering under any throttle input. It almost cut out through a set of lights just off the motorway slip road, managed to keep it going and then when I was back onto the flat I crept home at 2500rpm.

The joys of classic motoring. Speaking with the guys following, it would appear a few flames were shooting out of the exhaust on the backfires. I don't mind the occasional bang or pop but clearly, something isn't quite right when the car is not getting the proper fuel mix and almost stalling.

Looking for some reassuring advice. I will get the car into my local independent but would love to know more in advance.

[Jonny Hart]

That could be a sign of a CDI box issue. Did it worsen when the engine was warm?

[DustyM]

This ^^

And given that it was fine in the dry but the problem appeared in the wet and got worse I would check ignition leads, distributor cap etc for dampness...

[Tp81]

That could be a sign of a CDI box issue. Did it worsen when the engine was warm?

Yes. Only happened near the end of the run in both directions.

[Tp81]

Took the car out tonight and it made it about 100 yards before the same behaviour, sputtering and jerking. Neighbours probably wondering if I can drive a car with a clutch.

Couple of picture from last nights launch.

[Tp81]

Spare CDI unit from my E. Looks like it needs some love, small signs of corrosion. Will get this 100% before it goes into the car.



I see a few companies offering a repair service, can anyone offer a recommendation?

[hot66]

Tim ‘impmad’ on here

[Jonny Hart]

The electronic components in your CDI box are (almost) 50 years old and have lived though all manner of conditions ( vibration, heat cycles , damp). This is quite frankly incredible and is a credit to the original design.

Although they can be repaired, some places proudly claim they have ‘rebuilt’ the unit when in truth it has had the faultly components replaced. This does not address the age of the remaining components. I would estimate that more than half of the faulty boxes we see have been repaired at least once. Check what level of service you are getting.

Part of the issue is that there isn’t really a way of assessing the condition of individual electronic components. The only way of guaranteeing that a box is ‘100%’ would be to replace ALL the components which is impractical.

This is why we chose to start again and address some of the common failure modes with a new design.

Personally I find it odd that folks will spend plenty on engine builds and MFI pump refurbs then run with a 50 year old spark box. As far as I know all an engine needs is fuel, air and a spark, so it is a pretty fundmental ingredient!

[hot66]

if I was running original ignition system I've got to say Id be going with Jonny's new units

[Tp81]

Thanks for the advice. I have opted to go with Jonny's new unit.

[impmad2000]

Hi guys, I haven’t done any of these for ages. Since the CDI+ came out I haven’t seen any!!
I have always maintained that the parts used on the CDI were very good at the time of manufacture, but are probably 30-40 plus old by now. Modern components made to the old style ( through hole leaded parts) are no longer the primary components and so are probably not as good quality as the old original parts. For this reason I always only replaced parts that were broken.
The CDI+ uses the latest surface mount parts and these are manufactured to the latest start-of-the-art techniques. For this reason, I have given up testing old CDI boxes as there is no point. I believe CDI+ is the way to go ( or crank fire, distributor less ignition). There is also the additional benefit that comes with the new tech too.
My recommendation is to look up Jonny’s kit. I would .

[Bootsy]

Likewise, I'd look at Jonny's box - oh er, missus

[Tp81]

My car was originally supplied by Glen Henderson of Glasgow, and sold to its 5th owner in 1984 through Malaya Garage. I had never heard of them but I have been told another well known performance car garage of old. The car still has a sticker from them on the rear window, I like this in terms of history but this would have been changed out by the dealer, I managed to source the following from Dr Georg Konradsheim.

This would have been on the rear window of 75 cars and it is only right that it goes back on.

r