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Discussion Starter #1
Hi,

Can someone please tell me the purpose of the intake-side holes on DCOE Webers, as circled in red in the below photo?

Also, assuming these holes take in air, do they need to be protected by an air filter of some sort?

My reason for asking is that I'm thinking of fitting 40mm ram tubes with foam sock filters, but I need to know if these holes need to be filtered as well. The car will mainly be used as a daily driver, with occasional track day use.

Regards,


Nick
 

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Those holes bring air into the float bowl area and supply air to all of the mixing jets.
Best to filter them, althou some just use a fine metal mesh to cover them.
Any fine dust in there could ruin your day....
 

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Discussion Starter #3
Hi 101/105guy,

Thanks for that. Looks like I need to go for a airbox of some description to feed clean/filtered air into both the float bowl vents and the ram tubes... Australian roads are not exactly a dust free environment :D

Regards,


Nick
 

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There is very little airflow that goes into these ports. They normally receive filtered air from factory airboxes, but are commonly exposed in racing applications. You mainly want to keep big chunks out of there. There are numerous air filters such as K&N that will adequately protect the innards and breath fairly freely. Your horns have relatively coarse screens as well, and will flow a lot more dust into your engine than the float-ports that you have asked about. Unless you are actually racing and need the last HP, I'd put on any of the factory or K&N filters and improve the life of your engine. You'll need to re-jet when you replace the horns, of course.
 

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Discussion Starter #5
There is very little airflow that goes into these ports. They normally receive filtered air from factory airboxes, but are commonly exposed in racing applications. You mainly want to keep big chunks out of there. There are numerous air filters such as K&N that will adequately protect the innards and breath fairly freely. Your horns have relatively coarse screens as well, and will flow a lot more dust into your engine than the float-ports that you have asked about. Unless you are actually racing and need the last HP, I'd put on any of the factory or K&N filters and improve the life of your engine. You'll need to re-jet when you replace the horns, of course.
Hi DPeterson3,

Thanks for the feedback... and sorry, but just to clarify (I should have done so in my first post), but the photo I used is not of my engine... I just borrowed it from elsewhere on the BB to identify the holes I was talking about.

I'm still putting my intake system together, and I wanted to make sure of what I need to do with those float port holes when it comes to the air intake/filtering side of things.

As mentioned, I was thinking about foam socks over ram tubes, but that would leave the float port holes exposed, and mine will primarily be a street car. I'm now leaning towards a "Pipercross-style" airbox, perhaps with a cone filter on the end of it.

Regards,


Nick
 

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Why not a factory air intake system? They are quite good, and provide the connection for the necessary carb support rod, as well as remote pressure feed to the float ports. For some reason, Alfa has determined that having these ports fed by air away from the vicinity of the carburetor bores is a good idea. I have no problem with the K&N setup on my 102, but I'm working on how to adapt the original airbox.

In your case, there is the late style that has the filter inside the airbox alongside the carburetors, or the earlier style that feeds from an air cleaner assembly on the exhaust side of the engine. This earlier style has a "dished" cam cover to make room for the air snorkel that passes over the engine.

You can probably find the late style set up fairly easily, I would think.

g'luck
 

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Discussion Starter #7
Mine is not a standard setup. Long story... but I'm installing a Twin Spark engine into a GT1300 Junior. I was originally planning to keep the Twin Spark Bosch Motronic EFI system, but it's just too difficult to get everything to fit, so I'm going to install twin 40mm DCOE Webers and a modified Nissan/Alfa twin spark distributor. In summary, the stock Alfa twin carb airbox will not fit into the available space.
 

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If I recall, the modified Nissan setup fits into the normal spot on the lower forward right side of the engine. If that's the case, then why not use the over-the-engine snorkel set up of the 105's? Not sure it it will clear the twin spark head, however.

There's nothing wrong with a pair of KN boxes and a support plate. Works fine on mine.

Don
 

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Discussion Starter #9
If I recall, the modified Nissan setup fits into the normal spot on the lower forward right side of the engine. If that's the case, then why not use the over-the-engine snorkel set up of the 105's? Not sure it it will clear the twin spark head, however.

There's nothing wrong with a pair of KN boxes and a support plate. Works fine on mine.

Don
Hi Don,

I do like the over-the-engine setup, and I still have that from the original engine, but the valve covers on the original engine have indentations to accommodate the air intake, whilst the Twin Spark doesn't. Also, the Twin Spark is quite a bit higher than the Nord engine, so clearance under the bonnet (hood) is tight.

If I can't go down the Pipercross-style airbox route, then K&N boxes will be the next best option for me, I think.

Regards,


Nick
 
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