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Originally Posted by RandomUsername Does anybody here have a workshop manual for the Padmini S1? If so I would appreciate if you could photograph/scan and post the fuel system section. I'm desperately looking for information about the Solex MCS1069BICSA carburettor and the correct adjustment procedure for it. |
Solex 1069 BICSA was introduced as a part of 1991 emission norms. There were two variants, 1068- without the delayed throttle release with a delay valve and 1069-without the delayed throttle release with a yellow vacuum delay valve (the colour of the delay valve represents the delay)
The only person whom I knew could tune a BICSA correctly sadly is no longer amongst us. However, I would try to post in as much detail as I can, whatever he has taught me.
Unlike your conventional Solexes, setting up a BICSA is very different. There are three main adjustments, two of which are visible, one which is the most important one is not. If you look at the carburettor the way it mounts in the car, you'd see one single large spring loaded adjustment screw on your right. This is the idle air volume screw. On your left, sitting diagonally at the base is your micro fuel setting screw (on regular Solexes, this is the main fuel setting screw)
Now coming to the interesting part, the main fuel adjustment screw, which is to be set for the car to run correctly, is sealed at the company for emission purposes, however, it can be opened up. If you trace the line that goes from the main-jet to the micro fuel adjustment screw, you'll see a bob that's filled with epoxy like sealant. I am attaching a photograph with the said bob circled. You need to carefully drill it out to expose the main fuel setting screw.
The main fuel setting screw is super sensitive. If your car is running, you need to take the ensure that the micro fuel adjustment screw is about 1.5 turns out and then very lightly, screw out the main fuel screw till the idling rpm increases. At this threshold point where the RPM is risen, screw in the main fuel screw by 1/8 to 1/4 turn till the rpm drops slightly again. This is a coarse adjustment. Like the name suggests, fine tuning can be done with the micro adjustment screw. Finally proceed to the idle air volume screw. Turn it in till the rpm drops slightly and then turn it out 1/8 turn to the threshold till the idling rpm stabilises. If you have access to a tachometer, your idling rpm should be 750-800rpm with the delay valve disconnecting and the vacuum port blocked out during adjustment. Hope this helps.
On that note, I realised that this is my first post on this thread after Mr. Dhabhar's passing. What he has taught all of us is invaluable. Our favourite topic for discussion was fuel systems and engine tuning and I've spent countless hours with him discussing various subtle differences between various carburettors and distributors and how 0.08 mm and 0.09mm warm valve clearance is better than the company spec 0.1 dead cold clearance!
Although I was away from this thread for a while now, I promise to be proactive and help all Fiat fanatics out here on all the things he has taught me, to the best of my ability. I know wherever he is, he's surely following this thread
Warm Regards,
Adheesh Parelkar