S3 V12 Stromberg/Dizzy vacuum pipes

Technical advice Q&A
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muz122
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Joined: Tue Feb 05, 2019 1:20 am
Thailand

#21 Re: S3 V12 Stromberg/Dizzy vacuum pipes

Post by muz122 » Tue Nov 05, 2019 7:35 am

Hello again all, finally had some time to pay attention to the engine again, after sorting the steering.
Got a new FP valve (there wasn't one fitted before).
Set static timing to 8° BTDC (due to the 95 fuel here). On the snippet in Bob's comment, it states 4°ATDC at idle but the workshop manual I have states 12° BTDC at idle.

Anyway, I'm still faced with the same issue and I'm pretty confident weak spark is causing the rich rough running.
Here's a video of A1 spark at idle:
https://drive.google.com/open?id=1xeSHq ... tP3SlAGbQo
It's definitely not a strong blue spark. What got me started looking at the ignition was a poor strobe from the timing light when attempting the timing, seems worse on A1 than other cylinders although they all have a similar spark quality.
Any ignition parts that have been renewed, I've refitted the old parts in order to eliminate (cap, rotor, Magnecor leads). Even had the distributor out yesterday to give it a once over, no obvious defects found. The only thing I did whilst the carbs were off, was rewire the wipers which involved a lot of ignition on time whilst testing, so wondering about a cooked coil? In the workshop manual for OPUS, ignition on spec for coil negative to ground is below 2V. I'm getting approx 12V. It advises to renew the amplifier if above 2V.
Image


This system appears to be SNG or similar, so not sure if the workshop manual tests are leading me astray. Does anyone know of somewhere in the UK I could send the complete ignition system to for testing and supplying replacements? I’ve sent all the pictures of amp etc. to SNG but they are simply saying if it was theirs, it would have a label on it….there must be another way of identifying it?!?

Once again, thanks a million for all the help I’ve received so far.

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muz122
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#22 Re: S3 V12 Stromberg/Dizzy vacuum pipes

Post by muz122 » Tue Nov 05, 2019 8:58 am

https://drive.google.com/open?id=18Gjv9 ... hDrDniojjA

For those of you familiar with ignition scope patterns. Voltages seem alright (although no other car to compare to) but patterns seem rather erratic. Blue (primary around 240V, red (secondary around 13,500V).

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#23 Re: S3 V12 Stromberg/Dizzy vacuum pipes

Post by muz122 » Fri Apr 17, 2020 4:59 am

Quick update so as not to leave the thread open; sent the entire ignition system to England for testing, the company informed me it would cost little more to renew all components so I ordered the lot and issues resolved.
Thanks a million for all advice, I've learned loads about these engines in the process of diagnosing this issue and can now remove the carbs in 5 minutes!

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