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Weber DCOE 40s - Air Horns Required?


Insert34
Go to solution Solved by visionaut,

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Heyo!

 

New to the forum, and I just have a quick question. I don't have a 2002, but I plan on running a dual Weber 40 DCOE setup in my own car, and this is one of the most active & knowledgeable forums I can find that I think can help answer my question.

 

I plan on converting my car to a dual Weber DCOE 40 setup. It's a FWD car and the carburetors are on the firewall side of the car, which means no room for the large air filters, the tallest ones I could fit would be the 1 3/4" types. That, and since this is a daily, I can't run just bare horns or those clip-on meshes on the horns.

 

To my question: Since the horns that come with the carburetor are too tall to fit in the filter (leaves like a 2mm gap between horn & top of the air cleaner), am I able to run these without the air horns, or do I NEED to get special short horns?

 

To clarify further: the air horns on the DCOEs I'm getting are the one piece slip in style, with the two tie-downs on either side, like in the photo I attached.

 

Thanks!

Trumpets 40mm 1 1/2" Weber 40 DCOE slide in Velocity Stacks 2PCS ALLOY air  horns | eBay

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3 hours ago, Insert34 said:

I plan on converting my car to a dual Weber DCOE 40 setup. It's a FWD car and the carburetors are on the firewall side of the car, which means no room for the large air filters, the tallest ones I could fit would be the 1 3/4" types.

Sorry for having a FWD car.... 😉 

Your car will run without them too, but you'll lose power. Trumpets are the easiest and most reliable way to have proper airflow.

Even the shortest one will help, there are some very short thingies that'll only add a radius at the carb - better than nothing.

Edited by uai
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morning Insert, the person who built myhigh performance M10, with DCOE 40's,says the best power comes from when you use the air box to get an even amount and flow, yes he explained all the technical reasone, bounce back, reverb detonation, etc, but that was over my pay grade, but if you are around the East coast check in with Mike at Carlquist Competition engines in CT, good luck

IMG_4269.JPG

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Like mentioned above, get and mount  stubbies (air horns with just the horn radius). They only protrude about 3/8” from the carb body. With 40 DCOEs the velocity stacks sleeve in to retain the Aux Venturi, don’t run the carbs without any sleeves..

Old Alfas used to have a similar clearance problem running DCOEs, their solution was 90-deg curved  air horns.

Where we goin’? … I’ll drive…
There are some who call me... Tom too         v i s i o n a u t i k s.com   

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To repeat, yes get something with a radius.  It helps immensely with off-idle acceleration stumbling and smooth power delivery.

 

here’s an example of what you need…

W40-16b1.jpg
WWW.DELLORTO.CO.UK

Top quality machined alloy trumpets, exclusively made for us in the EU to our design. Made from...

 

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You cannot run that carb without at least the sleeve portion of the velocity stack, it holds the auxiliary Venturi in place. 
 

You can cut off the existing velocity stack portion and use a bolt on “stub stack” which can also fit inside your air filter housing. You could also make a very thin stub stack yourself out of 1/4 or 3/8 inch aluminum sheet if you have those skills. 
 

Velocity stack-less sleeves are also available pre made. 

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8 hours ago, Rich said:

morning Insert, the person who built myhigh performance M10, with DCOE 40's,says the best power comes from when you use the air box to get an even amount and flow, yes he explained all the technical reasone, bounce back, reverb detonation, etc, but that was over my pay grade, but if you are around the East coast check in with Mike at Carlquist Competition engines in CT, good luck

IMG_4269.JPG

 

Not to hijack the thread, but I have the same airbox set up, made by Tim Jason Performance, but can't find any filters for it.  It's a thin version of a Datsun 240Z filter, which I believe K&N made for the Clarion build.  The regular size won't clear the brake booster.  Anyway, I've contacted K&N and they've discontinued them.  Anyone know where I could find one?  Otherwise, I guess curved trumpets and UNI filters are the way to go. 

IMG_0487.jpg

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11 hours ago, jgerock said:

Hmm- intake side toward firewall. Do you have a water cooled VW?  Tons of forums exist for this information.

That's exactly the reason why I came here. All the other forums that might have more detailed info about DCOE setups like this are nigh if not entirely dead. This forum pretty much talks about them 24/7 every day, and I'm pretty sure here is the most intelligent crowd to come to for questions about it, without having to wait like a month for a guess of a response lol

 

Car is a 1989 Toyota Corolla sedan, by the way. 4A-F engine. Only like 300 TRD-special models in Thailand had dual DCOE's from factory, otherwise, no info. I have a friend who'll fabricate the manifold for me, and I've been able to find out all the details and etc otherwise from various forums, just the air horns is the only one with like, no info out there, aside from here of course.

15 hours ago, uai said:

Sorry for having a FWD car.... 😉 

Your car will run without them too, but you'll lose power. Trumpets are the easiest and most reliable way to have proper airflow.

Even the shortest one will help, there are some very short thingies that'll only add a radius at the carb - better than nothing.

Yee I totally understand that. I'm fine with losing a couple HP if it means I can run actual air cleaners, but looking at the rest of the responses, I 'll have to run small horns

9 hours ago, Rich said:

morning Insert, the person who built myhigh performance M10, with DCOE 40's,says the best power comes from when you use the air box to get an even amount and flow, yes he explained all the technical reasone, bounce back, reverb detonation, etc, but that was over my pay grade, but if you are around the East coast check in with Mike at Carlquist Competition engines in CT, good luck

I'd love an airbox, but they are extremely expensive from what I've seen. I don't mind running dual air cleaners thankfully. That, and I'm right in the midwest, Oklahoma, lmao

8 hours ago, visionaut said:

Like mentioned above, get and mount  stubbies (air horns with just the horn radius). They only protrude about 3/8” from the carb body. With 40 DCOEs the velocity stacks sleeve in to retain the Aux Venturi, don’t run the carbs without any sleeves..

Old Alfas used to have a similar clearance problem running DCOEs, their solution was 90-deg curved  air horns.

 

7 hours ago, AceAndrew said:

To repeat, yes get something with a radius.  It helps immensely with off-idle acceleration stumbling and smooth power delivery.

 

here’s an example of what you need…

 

 

7 hours ago, Lorin said:

You cannot run that carb without at least the sleeve portion of the velocity stack, it holds the auxiliary Venturi in place. 
 

You can cut off the existing velocity stack portion and use a bolt on “stub stack” which can also fit inside your air filter housing. You could also make a very thin stub stack yourself out of 1/4 or 3/8 inch aluminum sheet if you have those skills. 
 

Velocity stack-less sleeves are also available pre made. 

Thanks for the answer guys! Looks like I'll have to run some baby horns, or some sleeves like the Alfa's run apparently. 

 

Massive help, guys! It's only been a day and I got a full page of helpful insight and answers, I'll definitely come back for future DCOE questions I may have.

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Yup, you need stubbies with a radius.

 

As everyone else already said. 

 

Also, you HAVE to run a filter if you want the engine to survive.

I ended up making something goofy out of fiberglass...

 

t

 

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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3 hours ago, Insert34 said:

I'm pretty sure here is the most intelligent crowd to come to for questions

Yeah, duh😁, any radius at the inlet will help although, you'll miss any ram effect, but the position of your engine wins here. I've done webers on m10 for more decades than I can count and have tried many air cleaners and the best by far for a m10 with a up to 300' cam is the factory ti air cleaner, major boost to the low end which allows you to run larger chokes and jet for the top end.  

If everybody in the room is thinking the same thing, then someone is not thinking.

 

George S Patton 

Planning the Normandy Break out 1944

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