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Hi Ruedi,

As you note, the runners in the manifold in the pictures have not been finished to match the head or the adaptors on which the Webers are mounted. Once finished the runners in the manifold align properly with the carb adaptors/Webers on one side and with the runners in the head on the other side.

Like the runners in the factory Weber manifold for the 2600, these runners are designed for use with Weber 45DCOE9 carburetors and standard adaptors. Like all Alfa manifolds for 45 DCOE's, they start out with a diameter of 45mm to match the Webers/adaptors and tapering down slightly to meet the runners in the head. Even prior to finish the runners in the raw casting are within a millimeter or less of the proper alignment at both ends. Tight tolerance control is one of the big advantages of modern casting technology.

If you look closely at the lower picture in your post, it is possible to see the close alignment between the unfinished runner in the manifold and the finished runner in the head beyond. Once finished, the two runners mate up and the shadows disappear. This short of finish work or port matching is common with Alfa manifolds, whether installed at the factory or after market.

Regards, Lock
 

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Interesting observation about the size of the runners. I'll call Paul Hasselgren tomorrow and see if he can enlighten me in that area. On the other hand the flanges just may be larger than the original flanges and the ports sized for 45 DCOE carbs after all. I know that I will spend time blending the manifold to the runners on my 2600 engine. I do know that the first manifold Paul made was for a 2600 Spyder that is now 3 liters rather than 2.6 liters. Paul told me that particular car was taken to Europe and rallied and had very little problem keep up with Ferraris of the same generation. Paul has a very expensive and accurate dynamometer and the engine produced more than 200 horsepower with camshafts that provide good normal usage, not just race car performance.
 

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This is a really good post and has me wondering about moving to Webers or Dellortos from the Solex setup over time (and funds!) but I note there are a number of incarnations of the 40 DCOE and would love advice on whether/which ones are suitable for 2600's. The same applies to Dellortos I think.

For instance, on eBay UK, there are ones from Pinto, Holbay, Mini (!), etc., engines at reasonable prices.
So, would it be 'wise' to obtain 3 of the same and have them overhauled and re-jetted, could differing types work together (dubious), etc?
I have a spare parts engine that I am considering rebuilding given I'm trapped indoors that lacks carbs anyway so it shouldn't be a loss I reckon.

The new manifold is beautiful by the way.... hmmm....
 

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I contacted the office by telephone this week but he was doing work on his dynamometer and he didn't get back to me. I'll call the office again and see if the question about using 40 DCOE can be answered. I will post as soon as I can get an answer.
 

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Correct but there is information out there that indicates that the 40 DCOE might work better under certain circumstances. Mind you, I am not advocating one size over another but if the Hasselgren manifold permits, with modification, using either one so be it for those who want to go smaller. Any information for the 2600 community that is well tested and verified is always a plus.
 

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It’s risky to try and over simplify a complicated subject. However, I’ll try.

Both 40s and 45s can be made to work fine on any car, including the 2600. In general, the 40 was most often used on high volume 4-cyl production cars with engines from 1100cc up to around 2300. The 45s were used on larger CC engines and highly tuned versions of smaller engines.

A 2600 Alfa MAY have been originally targeted for higher-performance development, so the 45 was specified to accept the larger ventures appropriate for higher RPM and horsepower generation. Such development was limited, but the history of 45s remains.

When it comes to equipping an Alfa 2600 with Webers, both can be made to work equally well.

Yes, you should buy three, identical models. However, the model number may not be definitive for what’s inside. Used Webers may have had the progression holes modified, as well as different butterflies installed, or modified.

A cheap Weber is an expensive investment.
 

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According to Paul Hasselgren you could use 40 DCOE carburetors with the new manifold he has produced. Contact him directly and he will be glad to fill you in on the details of the project.
 

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