Aurelia engine not running well: ideas?

[Sebastien]

Our Aurelia B20 6th series is not running well. Everything is fine, until you are at full load on a lengthy motorway incline, starting at 3700 RPM in 4th. revs drop quickly, you have to get back to 3rd, and then you manage it up the hill at 4000 RPM in 3rd, just. The water temperature goes up, almost in the red.
The water circuit has been completely redone, including the water distribution in the block, the pump, the radiator. Water temperature is absolutely normal otherwise, including in traffic jams.
We suspected the ignition, especially the coil, but on a level road you get quickly to 5000 RPM in the 3 bottom gears. However the engine always feels a bit constricted, and is not as free-reving as it should be!
Now we are looking into fuel supply, we think that it is blocked somewhere and that we do not get enough fuel to the carb under full load. (the fuel system is the standard one, without electric pump, but with the new double membrane pump supplied by Cavalitto).

Has anyone other ideas, or suggestions?

[Randy Adams]

Hello Sebastien:

I will be interested in what you find the problem to be as I have one single carb Flaminia exhibiting similar behavior, except on my car it only does it when the weather is very hot. I still suspect the coil on my car and am sourcing another one. Or the condensor.

Is there any possibility that the advance in the distributor is not working right? Does your car use a vacuum advance mechanism? Bad ignition timing can make an engine overheat.

It does seem that your problem will be fuel delivery. You might want to review Huib's very helpful observations in the Fulvia thread in the "older messages" responding to someone's "Dellorto problems." He gives an excellent discussion of what the fuel pressure should be in a system with a mechanical fuel pump. Perhaps your new pump is not doing what it should.

[Geoff Goldberg]

Sebastien -

A few thoughts - it depends if you think the engine is struggling from some outside issue (fuel,ignition, timing) or if it is more deeply sick. A few quick thoughts - it might well be ignition (coil going, bad condenser, points, distributor wear, etc), or fuel (blockage in line, poor pump pressure - to be checked with a gauge for sure!). I've had some of these, the most pernicious being fuel pressure. It turns out that the difference of a paper gasket in the pump mounting can be the difference between 0 and 4 # of pressure. So check the pump pressure at the carb! I believe its to be around 3-4#. Sometimes these can be way off, or short and run out of fuel up higher in the revs.

If you think there may be a deeper problem (overall, there is a lack of power, no?), best to get into the compression/leakdown test. And then there is the nagging "is the cam OK?" issue. How many miles on the motor, etc? Compression and leakdown will tell you how things are, but try the leakdown also with the piston 1/2 way down, in case there is some problem mid-bore.

I suspect it is fuel related, at least at a first glance. I once had a problem where the B20 kept running short of fuel only in some times, and would stop for 20 minutes. Turns out the fuel hose off the tank to an elec pump was too long and getting compressed by the de Dion tube! You might try adding an elec pump, but if its run for some time happily on the mech'l pump, that wouldn't be needed.

Hope this helps.

[Sebastien]

Thanks, Randy and Geoff for your thoughts and comments.
Timing is OK, and points and distributor also (no vacuum advance mechanism on Aurelias).
Coil and condensator might be a cause, but the strange thing is it happens only under full load, when you floor the throttle. (Can you tell me if the behavior of condensator and coil depends on the load factor?)
We had the heads off when we redid the water tubes. The liners were OK, so we decided not to touch the bottom end. Oil pressure is healthy too! There was a bit of a leak on one cylinder head gasket, so we had the cylinder heads overhauled (valve guides and seats, surfacing the heads). So while the engine has some kms, it is not in bad shape, and we believe it is an outside issue. We took the car to Italy 2 years ago, and all was fine on mountain roads.
However now the lack of power is real, and not acceptable.
So the fuel system seems to be first culprit. We shall check pressure at the carb, and I shall report the findings.

[Gregor]

Hallo Sebastien!
Überprüfe doch mal die Benzinzufuhr im Tank oder am Reserveschalter. Eventuell ist dort ein kleines Leck wodurch Luftbläschen angesaugt werden. 1. Versuch: Umschalten auf Reserve. 2. Versuch neue Spritleitung versuchsweise legen.
Gregor

[Niels Jonassen]

I, too, would look at the fuel line and remember the bottom of the fuel tank. I have myself had a lot of trouble with an almost blocked filter where the fuel line leaves the tank.
Niels

[wim oude weernink]

Indeed, try the fuel tank filters, also teh one for reserve position. They can very badly clog, due to gum deposits, and almost block teh flow. Replace by new brass gauge, and the problem is most likely solved. Good luck.

[Huib]

Indeed, it sounds like fuel starvation.

I don't know if there is a glass fuel filter as on some Flavia's and Fulvia's. These have a pressure regulator in the cover. These are often dirty and are stuck limiting flow. These are always after the pump. Since you want the filter before the pump and the regulator after the pump I throw them out and install a plastic filter before the pump and a new regulator after the pump.

Is the tank rusty? When restoring a car I always have the tank thoroughly de-rusted and epoxy coated. Modern cars have plastic fuel tanks. Today and in the future one can no longer expect from the petrol companies that they mix in additives to preserve steel tanks if virtually 100% of their customers use plastic tanks.

I also replace steel fuel lines with cunifer fuel lines. Cunifer is an alloy of copper, nickle and iron. It does not rust. I also use it for brake lines.

A Gunson fuel pressure gauge costs about 25 euro. It is a good investment. The kit includes a T piece. Install it just before the carb. The fuel pressure should have the value as give in the specification sheet of the carb. Usually 03, to 0,35 bar for Solexes.
And above all, the fuel pressure should remain absolutely constant when you repeatedly flip the throttle. The real test is of course that it remains constant at high power but it is difficult to read the gauge when you are doing 150 or so. Operating the acceleration pump by repeatedly flipping the throttle simulates the higher fuel usage at high speed. Or you might connect a longer hose to the gauge and bring it inside the car.

Was the carb overhauled by a real carb specialist?
Some car mechanics are self proclaimed carb specialists but they are still light years away from the old guy who has done a million carbs, has all the documentation and above all all the right tools and test equipment.

[Argento Solita Pasternacke]

I personally have above 50 different Aurelia over period from some 40 years. Most are B20. Problem caused most often by unusual or mistaken parts in engine causing constriction of flowing fuel. Not dirty filter! Normal Aurelia run without problem with meth alkohol or kerosina, engine can take little dirt fine, when some additive put into tank for disolve residue. Suggest changing whole motor for something without complication! Lancia is nice for looking, but almost not for driving! I should know better than most other people!!

[Gregor]

You had 50 Lancia only for looking and not for driving??