Hi,

My experience and personal choices:
Conservation of the intake manifold by separating the ducts. I used specific resin (high T ° and resistance to gasoline) which I molded around cores to guarantee uniform conduits.
Here pictures on my 2000 :

Use of Weber 40 with the same setting as typo 105-1750:

• Buse : 33 mm
• Gicleur principal carburant : 120
• Gicleur Air : 150
• Tube d'émulsion : F 16
• Ralenti : 50 F 9
• Pointeau : 200
• Fond de cuve : 55

Result on my previous 2600T. The engine was fantatic !!!

 

Serge, could you please post a product shot of (or link to) the resin you used?

 

Of course :

Résine époxy HT résistante aux hydrocarbures.

Résine époxy Haute Température, spéciale hydrocarbures, essence et gas-oil..

www.mack-kayak.com

Wait 24 hours, then it is still necessary to heat 16 hours at 60 ° C and 6 hours at 90 ° C.

 

Curious. Has anybody tried the Solex carbs after separating the inlet manifold ports?

Pete

 

Pete, the Solex PHH carbs do not allow for that because one half of the carb feeds 2 cylinders, except for wide-open-throttle.

 

I'm not quite sure I get what you have done to divid the runners. What is the black material? Is it some sort of foam type of material or some type of material that you melt it once it's in place in the runners or do you pour resin around the black material and then remove or dissolve the black material? Please give a detailed explanation of the materials and the process you have used to form individual runners. Thank you!

 

Sorry, I'm going too fast ...
The manifold of the 2000 has ducts whose inlet diameter (at the carburetor outlet) is larger than the outlet diameter (at the cylinder head inlet). During the sealing operation, it is important to obtain a regular conduit.
I took a simple heating tube insulator (it is very common in France) :

I chose it with the right outside diameter (I don't remember exactly but on the 2000 it must be 45 mm). I reduced the tube so that it has the right diameter at the outlet of the collector (pictures 1 and 2 above).
A little silicon grease to take it in. I pierced the collector at the top.
Here a picture of the tube in one of the conduits.

I filled the space between 2 tubes with my resin.

After cooking, the release is done without problem, by pulling (sometimes by tearing) the tubes.
Finally I applied a paint that I use for the interior of the engine blocks, but it is not necessary. The way to the valve is very clean.

Don would tell you that it is better to use the OKP manifold for the 2000s because the conduits are linear (but that's another story). On the 2600 the conduits are less curved than on the 2000 and this technique makes it possible to have a very clean result with little effort and money.
If you don't want to do it by yourself, there is a specialist in France (Alfa Classics Motors) who machines the collector and fits a conical tube there.

 

Does the cast alluminum "cold air box" bolt up to the weber's like the Solex's do? Same bolt orientation.

 

Don is right.
Here are the “gender menders” on my engine :

 

The Solex PHH44 carbs do not have the same plenum attachment pattern as Webers. Various people have made “gender menders” to attach the original plenum to Weber’s.

Actually, I do not know if the OKP manifold has more efficient ports than your modified manifold. The poster’s question was regarding the 2600 in any case.

As part a very general statement, curves in intake ports reduce efficiency, but other factors may dominate. A changing cross sectional area can pose problems as well, but correctly done one can created an accelerated flow that improves cylinder filling and swirl.

I read a study several years ago that determined that intake manifold walls should be a little rough, not smooth, as this helped avoid fuel drops forming on the walls.

 

Very nice engine and engine bay

Pete

 

Any discussion of Weber conversions would be incomplete without noting that a full reproduction Weber manifold is now available from Hasselgren Engineering in Berkeley, CA. Paul Hasselgren, who made his reputation building and tuning modern and vintage competition engines, used 3D scanning techniques to produce an exact copy of the original Alfa 2600 Weber manifold. See attached photos. The manifold performs like a Weber manifold should and is available for about 50% more than a "converted" Solex manifold.

 

Thank you

 

OK, 2600 owners. Time to quitchyerbitchin and do it right.

 

Don, thanks for saying it like it is. It is long overdue. No more half a-sed crap that doesn't work properly for airflow like a correct Weber intake manifold does. For those of you who have 2600 Spyders worth a small fortune, it's hard to imagine that having a proper intake manifold isn't worth the cost that Hasselgren Engineering is asking for you to do it right. Noboby, and I mean nobody, has anything like it currently available. The manifold is work of art, for goodness sake. To finally have this available is a wonderful benefit for the Alfa community. I've got one coming for my 2600 Sprint and I can't waiting to move forward with my car.

 

What is the price he is asking?

Hein Brand

 

The price I paid is $3700 with everything on my manifold shown in the pictures except the thermostat, the Weber carburetors, the carburetor linkage and the "gender menders." The other fittings come with the manifold. I also ordered for an additional $600 the adaptors with rubber "o" rings to use instead of the rubber adaptors shown in the picture. I'm aware of the need for the rubber isolators for the carburetors but I'm fuel injecting my engine so I don't have to worry about vibration in the float bowls.

 

This is certainly by far the best Weber manifold reproduction I've seen -- and, given the quality and difficulty of making it, it seems to come at a fair price.

However, something worth noting is that the ports of the intake runners appear to be substantially smaller than on the original Weber manifold (see pictures below).

Whether this is so for making this manifold a better match for 40 DCOE carbs (which very likely are better for road use than 45 DCOE), and/or to leave enough meat on the bone for porting and polishing, I don't know. It is also possible that the pictures above were taken during an early fitting where such work was not yet done (which would leave the question whether or not such work would be included in the price).

Either way, potential buyers should be aware that even manifolds in such great quality may not just be a simple bolt-on replacement, but may require additional work (e.g. porting) for adapting them to their specific setup and/or needs -- and there's nothing wrong with that.

 

Beginning in about 74, I noticed that the 45DCOE9 was listed in the Weber factory catalogs as original fitment for the 2600 Alfa. "Huh", I thought. By the time I was selling Webers as part of my job with BAT/Geon, I'd also worked as the parts manager for an Alfa dealer that also sponsored the owners Alfa race car. The 45DCOE was generally considered appropriate only for very large capacity engines (at least on a per-cylinder basis). The 2600 has a per-cylinder volume very close to the 1750, and it was only when those were used as race engines that the 45 was brought into play. I'm using 45s on my 1959 2000 which has a 2300cc engine, itself having approximately 33% larger per-cylinder capacity than the 2600.

On the other hand, early 45's make no pretense about being economizing with fuel. The transition zone tends to run quite rich, avoiding flat spots. I ported my OKP manifold to match the 45s (they are intended for 40's), and things have been quite happy since the first start. I've done some adjusting, and am using a non-original E-tube from Keith Franck, but I've never had a hint of the transition bog that seems to bother 2600s with modified Solex manifolds, as well as some reports using a Weber manifold.

If these new manifolds are delivered with bores appropriate for 40s, I'd use them. Set each one up the same as for a Euro 1750, and betcha it works.

 

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

 

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.

 

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....

 

Has anyone heard from Hasselgren recently? I have an email and text to him last week, but no reply....

 

Greetings ! Hasselgren Engineering checking in with you all

 

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.

 

The original Webers for the 2600 were 45 DCOE 9

 

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.

 

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.