Fulvia Coupe running rich

[John.Morton50]

Hi everyone, another issue I could do with some help on. My series 1 -1.3 Rallye is running rich after the carbs rebuild, to the extent that the plugs were fouling up. I have fitted slightly hotter plugs which has reduced the fouling but not eliminated it. Is it worthwhile changing the main jets? Do they actually wear after 50yrs of petrol flowing through them? How about the idle jets?
I try to resist the temptation of changing things on the off chance that it will make a difference, so any advice will be welcome!
Take care, John

[Richard Fridd]

Rich before the rebuild?

[lancialulu]

I have never changed main jets other than if they were wrong for the particular engine. Seems more likely float chamber float levels could be too high. And or the accel pump circuit is opperating incorrectly. Who did the rebuild?

[nistri]

Of course, it is assumed that ignition timing and valve timing are spot on.

[John.Morton50]

hello again,
I did the carb rebuild myself (see previous post). It consisted of replacing the spindles with larger ones, reaming out the bushes. It worked a treat, the car now starts reliably and has stable tick over. It is difficult to say whether it was running rich before the rebuild as it was so unstable. The jets seem to be the correct size, 120, although for some reason my car has 35mm carbs instead of the 32mm as in the manual.
The float chamber level being too high sounds a possibility, especially as one of them stuck the other day and flooded everything with petrol!
The (electronic) ignition timing was set by a garage with a meter. The valve timing I did myself after a lengthy learning process, it could of course still be wrong but the engine runs well and pulls like a train.... (relatively speaking of course, it is only a 1.3!)

[nistri]

35 mm carbs are not ideal for an engine designed to have 32 mm ones.

[fay66]

35 mm carbs are not ideal for an engine designed to have 32 mm ones.

Thank you, that's interesting, I never realised that!
Having a 2c with 32's as standard, although changed for Dellorto  Dhla 32's, I must say she runs very sweetly, although always on the rich side.
Brian
8227

[nistri]

Dell'Orto carbs are truly excellent and much better than Solex, Weber etc. The quality of their components is very good indeed.

[lancialulu]

Which 1.3 Coupe ran 32’s?

[nistri]

Sorry, 1.2 engines had 32 mm carbs.

[Richard Fridd]

Fouling on the open road or only in town?

  Richard

[Wangler]

I’ve got the same problem with my plugs fouling.

The car goes perfectly well on a long journey with no misfiring at all. However, on taking it out of my garage a couple of times it has been running on three cylinders. On each occasion a plug had fouled.

I’ve just tried Tim Heath’s dipstick method and the floats appear to be sitting much too high. The question I now have is how do you access the floats? I’ve got a horrible feeling that I’ll have to take the carburettors off, but I’m hoping not.

[lancialulu]

you can take the tops off the carbs to access  the floats. Note when you take the top off the levels will be indicated incorrectly for 2 reasons.1, fuel above the needle valve will be released into the chamber, and 2, the float will no longer be depressed. So only way to see correct level is with the top fixed.

Several reasons for incorrect level. Fuel pressure too high, float valve failing, float bent (by previous attempt at rectification), incorrect thickness of copper washer under float valve - Solex fitted either 1mmor 0.5mm back in the day but most repair kits supply 0.5mm.

I have been told that spark plug colour is mostly due to idle mixture so if sooty then too rich.

[Wangler]

Thanks Tim, that’s very helpful. As ever you are a font of knowledge.

Regarding sooty plugs, which is a pretty good description of mine, I recently increased the size of my idle jets to 49, so that wouldn’t have helped, but is there way of making the tickover mixture leaner?

I’ll try to take the car out soon and see what the plugs look like after run at a reasonable speed. I understand the best way is to put it into neutral then turn the engine off and coast to a stop to avoid any chance of sooting up at low revs.

I’m starting to appreciate why fuel injection was invented!

[John.Morton50]

Tim, thanks for the advice. I have added a second copper washer to the float valves, lowering them a bit and hence reducing the petrol level. This has made a big difference, the spark plugs are now perfect although it does mean I need to use the choke to start from cold. It just shows how sensitive these Solex carbs are!

On a completely different issue, the car is going in to a local tyre shop/garage for a steering alignment check using their Hunter Hawkeye Elite 3D machine. They have obtained the data for a Fulvia Coupe which is great, the alignment had previously been done by another garage after the rebuild but I had little confidence in them and the car felt worse after they had fiddled with it than before. The main issue is lack of self-centering which I understand to be the caster angle. Not that it is adjustable of course, but I would like to see all of the figures. Maybe just setting the tracking properly will help. I shall keep you posted!