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Discussion Starter #1
I just took my Spider to the Highlands for a proper road trip.

One thing that surprised me was the high fuel consumption, especially with Super unleaded being over £1.40 per litre...it was starting to bug me a little after 1000 miles in three days...

I have a 166 which weighs another 500kg, has another 1000cc, 16 extra valves, runs on 95, which I have always considered "juicy", but will do better mpg than the Spider....

OK, I know the Spider is old fashioned carbs, and I believe my Alfa mechanic sets them up to run rich, "because the engine is happier"

From a performance point of view the 2000 Veloce seems to have plenty of zip (nothing like the 3.0 V6 obviously), but I wonder if there is a way to test the performance and economy of these old cars...rolling road carb set up specialists?...changing the old distributor to a 123 maybe?

I suppose as I only do about 3,000 miles a year I haven't noticed the fuel consumption to date...but I reckon it does about 22mpg on mixed, fairly enthusiastic driving, and 28mpg on a long trundle at about 65-70mph...

Oh, and another thing, the engine has been running a bit hot as I had a crappy thermostat in...so maybe this may not have helped the fuel consumption, but I can't think how/why.

Cheers!
 

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Hi, your fuel consumptiom of around 28mpg on a long run is about right for a 2000cc Twincam. 22 when caning it is ok too.
If your plugs are sooty after a good run (don't check them after it's been idling for a long time), then it could be running rich, and could maybe do with a re-tune which will help.
My Giulia Ti Super Rep, ( with 123 dizzy and a fresh engine), on a run to Classic Le Mans last year, with lots of Mway driving, mixed with French A & B roads, did, 34+ mpg, but under normal circumstances is about 25 - 28 with a mixture of caning it and longer runs.
A session on a rolling road with an old school guy that knows his stuff would help.
My original '72 handbook for a new 2 litre GTV states 23.6mpg average with a full load, so we're both comfortably inside that !
Running a little hot wouldn't have affected the consumption excessively.
 

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2017 Guila 2.0 Tbi Lusso spec, 1972 S2 Spider Junior, wife drives 939 Spider, + Abarth 595
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I dont think you should be getting concerned over fuel consumption of a classic unless its completely off the scale. In comparison, my wifes 939 2.2JTS Spider only does between 25 - 30 mpg
 
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I get about 30 mpg is on cross country runs, sometimes enthusiastic, sometimes cruising depending how the mood takes so yours is a bit down, I used to get 25 max out of my Vitesse's and rarely more than 35 - 40 out of my minis so I've always considered the Alfa pretty good for something that powerful (in its day), the long legged gearing really helps , most of the Brit iron was desperately under geared and pretty heavy. End of the day it depends on how heavy your right foot is, Alfa's do respond well to a tuner who knows what he's doing, running them rich isn't necessary .
 

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My 2.0 Alfetta saloon does 32-34 mpg on a long run cruising at 60-65 mph, so your Spider isn't so far behind that.

One (often overlooked and misunderstood) component you might want to check is the vacuum advance on the distributor, if fitted. Vacuum advance is an economy device that advances the ignition timing by up to 10 degrees extra, but only when you're cruising on a light throttle. Under these circumstances volumetric cylinder filling is reduced because the throttle plates are almost shut which results in a slower-burning cylinder charge. Advancing the ignition means there's enough time for complete combustion which improves efficiency and mpg. Road cars spend quite a lot of time cruising with the throttle only slightly open (i.e. with high inlet vacuum) so this can actually have quite a big effect on mpg

If yours has vac advance, I can explain a simple way to test it.

Just a thought....
 

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Discussion Starter #7
My 2.0 Alfetta saloon does 32-34 mpg on a long run cruising at 60-65 mph, so your Spider isn't so far behind that.

One (often overlooked and misunderstood) component you might want to check is the vacuum advance on the distributor, if fitted. Vacuum advance is an economy device that advances the ignition timing by up to 10 degrees extra, but only when you're cruising on a light throttle. Under these circumstances volumetric cylinder filling is reduced because the throttle plates are almost shut which results in a slower-burning cylinder charge. Advancing the ignition means there's enough time for complete combustion which improves efficiency and mpg. Road cars spend quite a lot of time cruising with the throttle only slightly open (i.e. with high inlet vacuum) so this can actually have quite a big effect on mpg

If yours has vac advance, I can explain a simple way to test it.

Just a thought....
I don't think my Spiders does have this, I can't see any piping from the inlet manifold. If it did then it has long been disconnected.
 

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I don't think my Spiders does have this, I can't see any piping from the inlet manifold. If it did then it has long been disconnected.
I think Bosch distributors do but Magneti Marelli (as with mine) dont have vacuum advance. On a 3000 mile trip in the summer to Italy, I got about 30mpg, but a shake down drive earlier where we got stuck in traffic I only got 22mpg
 

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The Bosch distributor on my Ti Super Rep, my 2000- Spider, and also my previous 2 x Coupe 2 litres didn't have vac advance, maybe it's a later thing ?
 
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