[Expertees]

I have Weber Carburetors in my 1977 Alfa Romeo Spider and I'm not really sure what the advantage is but i’ve seen many people switch. It's a canadian model but I'm sure it previously had a SPICA fuel injection system. What are the advantages and disadvantages of both options and should I switch from Weber to fuel injection? If not, how can i tune the Weber carbs to get maximum HP because i feel like they might be running rich as i smell strong doors of gas at idle.

 

[180OUT]

Having run both Spica and Webers, I much prefer Webers. But basically it's a matter of taste because a well tuned Spica FI system works very, very well. I may be wrong but I don't think the Ca. Alfas has Spica as most that I've seen (mostly earlier cars than yours) had stock Webers. If you're concerned that your Webers may be running rich, the first step is to pull the jets, write down what they are, and then compare yours with the stock jet diagram on the Centerline site. Do you have a Weber manual? There are several good ones in print. I suggest that you buy one of each and study them because each will have some info that the others don't. Then, for a graduate course in Weberology, get a copy of John Passini's Weber book. It'll take awhile to grasp what he's talking about but, when you do, you will have accomplished something.

 

[Gubi]

I mean, I'd never suggest someone switch from SPICA to Webers, but if you've got Webers already it doesn't make any sense to switch back. Webers will work fine, sounds like you just need to get them sorted out.

I'd suggest figuring out what jets you've got, determining how your fuel pump system is set up, and verifying fuel pressure as a good starting point. Fuel pressure needs to be 3 PSI or less: too high and you get rich running. That's pretty common for folks to mess up in the conversion so that may be your problem.

 

[0die]

Haynes has a good Weber book as well. Has specs for Alfa Romeo jetting.

 

[alfaloco]

Not only correct jetting, but float level verification is very important also with carburetors. The float level and float drop must be within spec, measured with an appropriate gage.

 

[IvoOrdway]

Spica does have some advantages over many carbs. I like having it on my '78. However, I probably wouldn't swap for it if you have carbs now any gains from the swap would be negated by the lack of experts on the system. (they do exist but most mechanics prefer Webers just out of familiarity)

 

[goats]

Advantage to Spica is self adjustment for altitude. If you like to drive the mountains Spica might run a little better, all else being equal

 

[bianchi2]

as a kid.. in the 60's everyone wanted a f.i. ( fullie ) car now everyone wants to take a f.i. can and stuff a controlled fuel leak onto the car..strange....my self, i would always instale a fuel injection onto a car.. remove those damnd fuel leaks( did that to my freinds 66 corvair corsa... ran better better fuel mileage,, faster.. )

 

[Peter A]

Send a pic of your set-up. SPICA or Weber, each has its supporters and +/- so on a stock car it is a push. If it is a factory set-up, keep it. I like carbs, but a correctly adjusted and matched SPICA runs strong and reliable, easier to start and less likely to foul plugs. Carbs sound better, easy to start if you do it correctly. I had both. Get your carbs rebuilt and adjusted by a professional or with professional guidance. If you do SPICA, get a '74 pump set-up. Modified engines have more considerations.

 

[yvesmontreal]

Your car is definitely a US spec car and was originally fitted with Spica injection, like all Alfas sold in Canada after 1971. The underhood photo you previously published shows that your car was converted using a Euro spec Weber manifold, which is the best way to do it. If you want to go back to Spica, it also means you need to replace a lot of hardware, plus the cost of a rebuilt pump - we are talking thousands $$$ here.

As others have said, first tune your Webers properly, there is no reason they should run that rich. I have a bunch of spare jets if you want to try.

I just reinstalled the rebuilt Spica pump on my GTV: the main difference is +15% mpg compared to Webers (9 l/ 100 km in daily use). Webers are simpler to deal with, especially when you want to extract more performance using different cams, head work, etc. I once commented that Spica and Webers are like using a Mac or a Windows based PC. The Webers will work OK most of the time, but you will have to fiddle with them once in a while. Spica works well all of the time until something major happens, which is really not often, but then you are in trouble.

Edit: But I'd pick either system waaaaay before I would consider running an old car with Bosch injection. Reliability and performance of an old electronic system depends on a number of sensors and actuators, many of which are NLA, and of corrosion free connexions. And on a S3/S4 Spider, it makes the engine draw air through a straw and muffles the induction noises to make it sound like a Tercel. Geee.