Upgrading from Dual Weber 32/36s to Triple 40 DCOEs – What else do I need?

Paulaner

Paulaner

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Hey everyone,
I’m in the process of buying a set of triple Weber 40 DCOE carburetors from another member here on the forum to replace my current dual Weber 32/36 setup on my E3 bavaria.

I’d love to get some advice from those who have done this swap before. Aside from the carburetors themselves, what is the complete list of supporting parts I’m going to need to get everything installed and running properly?
Specifically, I'm looking for recommendations/guidance on:

Fuel system: Do I need an aftermarket low-pressure fuel pump and a pressure regulator to keep pressure around 3 PSI, or will the stock mechanical setup suffice?

Air Filtration: Recommended air horns, or filters.

Ignition/Timing: I currently run an Allison (Crane Fireball) optical trigger ectronic ignition. Hoping to keep this in place if possible. Not sure now tuneable it is though.

Throttle linkage. Can I retrofit the existing throttle linkage used for the dual Weber setup? Or do I need a dedicated 3 carb linkage?

Anything else like Vacuum lines, fuel line, filter, AFR gauge, anything else you think of LMK.

WTB / Looking to Buy:
If anyone has a intake manifold or a complete linkage setup (top-mount, bottom-mount, or cable/rod) sitting in their shed or taking up shelf space, please send me a PM!

Thanks in advance for the advice. Here is a pic of my current setup

1786908767839.jpeg
 
I'm right there with you. I just purchased three Weber DCOM 40. Unless I can source a single piece intake manifold, I will be purchasing the following:
www.piercemanifolds.com

BMW 3.0 Manifold & Linkage 99004.094 - Shop Today

Pierce Manifolds is a car parts online store offering this BMW 3.0 Manifold & Linkage 99004.094 and more Weber parts online today.
www.piercemanifolds.com
 
i will caution you, it is my understanding that you might have an issue with the brake booster - some people have had to go to the tii booster (depending on intake manifold), Korman used to state that you might also have an issue with the thermostat housing. i haven't put triples on the m30 in the e3 or e9 so this is just what i remember hearing
 
Kyle - The most obvious thing you need, as Steve notes, it intake manifolds. The M30 coolant spacer will also be necessary in order to fit the first carb.

The carbs will come with an interlink setup based losely on this, but modified because this is a two carb setup: https://www.carburetion.com/Products/ProductDetails.aspx?Part=99006.110. Roughly, you connect the rod from the bell crank to the first carb. That connection has a lever that slides into a connection on the second carb. The second carb has a lever on the other end, that slides into a connector on the third carb that is similar to the connector on the second carb. I am using this setup in my car now. You can see the interlinks in the picture below (this is my current setup, but without the topside return springs on the carbs).

I am running a Pierburg fuel pump with a revolution motorsports relay/controller. https://e9coupe.com/forum/threads/vapor-lock-electric-fuel-pump.34361/post-422763

I changed to a tii brake booster. It is longer but not as big around providing more room for horns. It provides a little less boost that the e9 booster, but you get used to it.

I have a 123 distributor and I like it a lot. There is a lot of information here about programming the 123 for use with triple Webers, mostly posted by @Stevehose who blazed the trail on this one. https://e9coupe.com/forum/threads/123ignition-distributor-install.16396/post-113188

For horns, I have a set of replica Alfa Romeo GTA horns.

Engine Bay.jpg
 
I found this link for the Pierce M30 intake manifolds:
www.piercemanifolds.com

BMW 6 CYL INTAKE MANIFOLD FOR TRIPLE WEBER DCOE CARBURETORS 8-0058- SHOP NOW

BMW 6 CYL INTAKE MANIFOLD FOR TRIPLE WEBER DCOE CARBURETORS 8-0058
www.piercemanifolds.com


@rsporsche : I didn't find a mechanical drawing on the Pierce website. For clarification: I assume these M30 manifolds are "low profile" or minimum height, which helps with clearance issues when the triple DCOE's are installed ?
 
I have these (or similar) on my m30. Although I have a Tii booster, I have not installed it yet. I am just able to clear with the shortest of air horns and filter covers.

I also use Hal’s water inlet spacer. On my first go-round with installation of these I could not make the spacer work with the original water pump pulley, there was interference. I now use a smaller pulley and all is good.

IMG_3080.jpeg
IMG_3079.jpeg
 
rblongboarder said:
I found this link for the Pierce M30 intake manifolds:
www.piercemanifolds.com

BMW 6 CYL INTAKE MANIFOLD FOR TRIPLE WEBER DCOE CARBURETORS 8-0058- SHOP NOW

BMW 6 CYL INTAKE MANIFOLD FOR TRIPLE WEBER DCOE CARBURETORS 8-0058
www.piercemanifolds.com


@rsporsche : I didn't find a mechanical drawing on the Pierce website. For clarification: I assume these M30 manifolds are "low profile" or minimum height, which helps with clearance issues when the triple DCOE's are installed ?
Click to expand...
it looks like Lance is using those manifolds. they look to be shorter than some. definitely shorter than the original Korman manifold.
 
Thanks for all the feedback. Some really good thoughts and parts recommendations to consider. Time to study up! This upgrade will certainly keep me busy throughout the winter.
My wife is wising up and starting to question my parts buying habit as am I for that matter :p
 
keep in mind - there are things that you do that are
1. routine maintenance,
2. there are things you do that add performance and
3. there are things you do to provide increased reliability.

we all know routine maintenance is necessary to keep the car from declining. things you do for reliability keep you from losing interest in the car - to keep it from letting you down. then there are things that add performance add excitement and generally add to value because it is easily recognizable.
 
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I have the pierce manifolds sitting in my garage waiting to use, also. They look good. Also the basic linkage kit from Pierce.
I’m actually going to go boosterless for my brake set up and run dual masters front/rear with a 5/8” front and 3/4” rear. I just want that booster gone to free up space..also trunk mounting my battery..:-). Looks like a few of are getting ready to go this route.
I’m in an e3, btw..
 
Ohmess said:
Kyle - The most obvious thing you need, as Steve notes, it intake manifolds. The M30 coolant spacer will also be necessary in order to fit the first carb.

The carbs will come with an interlink setup based losely on this, but modified because this is a two carb setup: https://www.carburetion.com/Products/ProductDetails.aspx?Part=99006.110. Roughly, you connect the rod from the bell crank to the first carb. That connection has a lever that slides into a connection on the second carb. The second carb has a lever on the other end, that slides into a connector on the third carb that is similar to the connector on the second carb. I am using this setup in my car now. You can see the interlinks in the picture below (this is my current setup, but without the topside return springs on the carbs).

I am running a Pierburg fuel pump with a revolution motorsports relay/controller. https://e9coupe.com/forum/threads/vapor-lock-electric-fuel-pump.34361/post-422763

I changed to a tii brake booster. It is longer but not as big around providing more room for horns. It provides a little less boost that the e9 booster, but you get used to it.

I have a 123 distributor and I like it a lot. There is a lot of information here about programming the 123 for use with triple Webers, mostly posted by @Stevehose who blazed the trail on this one. https://e9coupe.com/forum/threads/123ignition-distributor-install.16396/post-113188

For horns, I have a set of replica Alfa Romeo GTA horns.

View attachment 224650
Click to expand...
rsporsche said:
keep in mind - there are things that you do that are
1. routine maintenance,
2. there are things you do that add performance and
3/ there are things you do to provide increased reliability.

we all know routine maintenance is necessary to keep the car from declining. things you do for reliability keep you from losing interest in the car - to keep it from letting you down. then there are things that add performance add excitement and generally add to value because it is easily recognizable.
Click to expand...
boonies said:
I have these (or similar) on my m30. Although I have a Tii booster, I have not installed it yet. I am just able to clear with the shortest of air horns and filter covers.

I also use Hal’s water inlet spacer. On my first go-round with installation of these I could not make the spacer work with the original water pump pulley, there was interference. I now use a smaller pulley and all is good.

View attachment 224656View attachment 224657
Click to expand...
Is that a block off plate where the old mechanical fuel pump used to rest?
 
Last edited:
rsporsche said:
keep in mind - there are things that you do that are
1. routine maintenance,
2. there are things you do that add performance and
3/ there are things you do to provide increased reliability.

we all know routine maintenance is necessary to keep the car from declining. things you do for reliability keep you from losing interest in the car - to keep it from letting you down. then there are things that add performance add excitement and generally add to value because it is easily recognizable.
Click to expand...
@rsporsche couldn't agree more and a good reminder for us all though. I am getting close to running out of maintenance and refreshing to do on the car. Apart from front wheel bearings and brakes this thing has been given new life front to back.
 
you know, the 4th on the list remains unmentioned ... its the things that cost money and you covet. the things that we all tell ourselves will add to overall value. a petri or alpina steering wheel. real alpina wheels (16" or 14") or BBS RS wheels. we are talking about the jewelry that makes our coupes our own statement.
 
Paulaner said:
Is that a block off plate where the old mechanical fuel pump used to rest?
Click to expand...
Yes, the plate I used is this one: Here’s a link: https://ebay.io/m/ijiiaX. HB Chris recently mentioned that 2002 FAQ also has a block-off plate for sale. Here is a link to theirs.

I am using a Weber electric fuel pump that I put next to the fuel tank. That is powered through a Revolution Electronics controller. The revolution controller adds some safety to the mix, it will only power the pump if it sees a signal from the tachometer which shows that the engine is running.

I have a combination fuel filter and pressure regulator that I mounted underneath the coolant overflow tank along with a pressure gauge.
 
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