DIY - Triple Weber install

OK I have pulled the trigger and am heading to the Dark Side with a set of Italian triple 40 DCOE webers - I will be detailing the trials and tribulations of rebuild and install in the coming weeks. I love my Zeniths but am fascinated with the plumbing and exotic potential of 3 side drafts. So for this experiment I am thinking:

-Ramflo style foam filters for brake booster clearance (or are low profile paper filters better?)
-Carter 4070 low psi/high volume pump mounted underneath and heavily insulated/isolated for noise reduction
-Regular base gaskets instead of soft mount o-ring ones
-metal can fuel filter
-inertia cutoff switch
-old mechanical fuel pump cover plate from Carl N.

I would appreciate hearing from current triple owners on any tips/advice to consider so I minimize noob mistakes.

Do I need to relay the pump and/or how should I wire it?

What else to consider (besides saving for gas money)?

I want max induction music :mrgreen:
 

rsporsche

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Gianni,

be very careful which cam you choose. my experience is that cams with 300+ duration generally accelerate very quickly, make their power high up in the revs ... and have very little low-end torque. my 2002 - w/ 11:1 compression, schrick 316 cam and twin 45 dcoe carbs produced 185+ hp out of 2 liters, had a very lumpy idle ... but rev'd to 7500 rpm and loved to be driven above 4500 rpm. made very little torque down low. it also struggled to make enough vacuum for the brakes.

this is what Korman produces in their stage 2 (m30) engine
Stage 2 Engine-Carbureted
Our most popular performance rebuild for carbureted M30 engines. Produces 250 smooth, reliable horsepower (3.5 liters).
Parts Include:

  • Triple Weber 40 DCOE carburetor kit with Korman 1 piece intake manifold
  • Korman K-300 Camshaft
  • Mahle High Compression Pistons
  • Korman Rocker Arms
  • Stahl Headers
  • Performance Distributor (where applicable)
  • Bosch Sport Coil
These engines also receive our Stage 2 cylinder head porting and polishing, Stage 2 connecting rods, and engine oiling system modifications. Substituting the Schrick 284 cam yields 240 HP (3.0 liter), 250 HP (3.3 liter), and 260 HP (3.5 liter).
 

waynesie

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Rsposche - My race 02 is similar to your street set up, but with 12.5:1 CR and race gas. not sure what chokes you were running, but I started with 40mm chokes and the motor would stumble until 4500 rpm. I went with 36mm chokes to improve the lower end tourque and it made a difference. Pulls hard from 4000 up...

I am working on purchasing a triple set of 40 DCOEs for my coupe. I also have a complete EFI set up, but decided I wanted to try these first.... I love the look.
 
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rsporsche

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Wayne,

i have no idea what chokes were on the 45s ... korman did the entire engine setup. if you keep the revs up - it flies. i unfortunately don't own the 2002 anymore - i almost bought it back when it sold on ebay last month ... but the seller wouldn't tell me who rebuilt the engine or what they did to it.

scott
 

DerSchwede

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Hi Steve,

I've read your Weber story a few times by now - nice work carried out!

What setup did you end up with in the end?
Did you go with the semi-soft mountings with the intergrated O-ring towards the inlet manifold?

I'd love to see some pictures of the hidden AFM installation you mentioned :grin:

Best regards
Anders
 

jmackro

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Webers when matched to the engine are great but you can definitely OVER CARB your engine..

This stuff isn't black magic - there is a formula linking engine displacement, peak rpm, and carburetor size. It's: choke dia (mm) = [single cyl disp (cc) X peak power rpm / 2500] ^ 1/2

See: http://7faq.com/owbase/ow.asp?HowDoI%2FTuneWeberCarburettors and no, the above formula doesn't appear there, but it's what's behind the chart labeled "engine size, venturi size, and rpm".

Note that this applies to engines with one choke per cylinder; i.e., three Weber DCOE's on a 6 cyl engine. So for example, a 3.0 CS displaces 2,985 cc, or 497.5cc/cyl. Peak hp is at about 5,800 rpm. So the choke diameter works out to 33.97 mm - call it 34mm. Then, the carburetor size should be 1.25X the choke, or 42.47mm. So for this application, you could either round up to a 45 or down to a 40 - the key is to use that 34mm choke.

That is consistent with what Waynesie reports in post #62 above. Although he was working with a 2002, the single cylinder displacement is the same, 497.5cc.

Certainly you can run larger choke sizes with larger displacements and/or higher peak rpms. But putting too large a choke on an engine results in airspeed through the choke that is too low to draw fuel - that old hot rodder Daniel Bernoulli figured this out.
 
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Stevehose

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I've been meaning to update this thread. What a long, strange trip it's been. I could not get my DCOE32's to run to my satisfaction. Either too rich or too lean and I was tired of dumping money into the Pierce Manifolds black hole on jets :razz: All is not lost, because a rare VGS manifold came with my carbs and I got both for what just a manifold just sold for on eBay DE yesterday. It allows clearance from the thermostat housing and brake booster for trumpets/filters. I tried every soft mount made and never felt confident with any that they wouldn't leak so I just use thick gaskets. With our 6 cylinder engines, vibration shouldn't be an issue if everything else is set up correctly. So far no problems and definitely no leaks.

So I broke down and bought a set of rebuilt 40DCOM with 32mm chokes for torque from Alfa1750 on ebay, they will set you up with your preferred linkage and basic jetting and desired choke size. There is not much written about the DCOM, most of it is incorrect, but basically they were the last Italian Weber made and they incorporated what worked best from DCOE's and Dellortos. They share idle and main jets with DCOE, carriers and e-tubes are different. Then fuel injection killed them. What attracted me to these, besides being rebuilt to all factory tolerances, is that they have ports for both ported and manifold distributor vacuum advance and idle airbleed screws to balance each barrel. They also have adjustable accel pump diaphragms like Dellorto's. 5 transition holes for smooth off idle and progression. Once on it took me 15 minutes to get them all synched perfectly. I bought a metric drill set from Pierce a while ago to do my own jet sizes and I dialed in some idle and main jets and it now runs to my satisfaction. 13-14 around town and cruise, 12.5 on WOT. I drove it around all weekend with a big grin on my face. Currently using manifold vacuum advance to good results. Have tried both and prefer the advance at idle. So if anyone is considering buying used webers, preferably make sure they are previously from an M30. Otherwise be prepared for rejetting etc. The AFR gauge is essential to have but it also drove me to the point of obsession to tune it to my liking. I suspect most intallations of triples on our cars run rich if not done with the gauge. So use this technology judiciously.

Here's the finished product, along with the AFR install. If anyone has questions about my 10 month journey, feel free to ask, I may be able to save you some money and frustration! Tip #1 - buy the drill set and a couple sets of smaller than needed idle and main jets, then you can start lean and gradually drill the fuel and air bleed jets sequentially and dial in your AFR instead of guessing and ordering from Pierce every Sunday night lol.

The AFR gauge is an Innovate G5 that I carefully pryed the bezel off and grafted a VDO Series 1 bezel (the other 2 gauges) onto (they do not match so it took some delicate engineering!), as well as painted the needle from orange to white. Only drawback to the G5 is that it is not dimmable, and I see a small speck of orange at night but no biggie in the end. And it's all reversible.

IMG-20130330-00336.jpg


IMG-20130329-00332.jpg


IMG-20130329-00330.jpg



Hi Steve,

I've read your Weber story a few times by now - nice work carried out!

What setup did you end up with in the end?
Did you go with the semi-soft mountings with the intergrated O-ring towards the inlet manifold?

I'd love to see some pictures of the hidden AFM installation you mentioned :grin:

Best regards
Anders
 
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waynesie

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Nice.

Steve - Can you share a picture of your manifolds from the front (or rear) of the motor. I wanted to see the shape of the VGS one you have. I have seen pictures of the manifolds, but never mounted on an engine. Does the carburator air horns still interfer with the brake booster?
 

Nicad

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That is a neat and tidy installation Steve. This turned out to be quite a journey. How do you describe the change in throttle response and top end with the webers? If you can filter out the audio enhancement, do you feel you have gained much HP?

I bought the same gauge panel as you and was playing around with it last night. I am torn between this location vs under the radio. I thought I'd orient it with the central gauge on top rather than the bottom. I have a bit of a busy looking AF gauge unfortunately. (in inventory since the insurance company banned SC in my Miata), It has a digital readout.

Do you have a fuel pressure gauge on your car?
 
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wmnewlife

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triple webers

Steve I just purchased a set of DCOM's and a manifold. Where did you get the foam air cleaners, and are there velocity stacks under them. Thanks Walter
 

Stevehose

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Walter: What jets do you have, did you buy from Alfa1750? If you want I can send you what I ended up putting in mine.

I have these short angle ones from Spruell (they're black not green and had to be made to order).
http://www.spruellmotorsport.com/air-filter-weber-dcoe-short-angle-p-2366.html

filter_40_DCOE.JPG


I also have the ones that Pierce sells which are the same manufacturer (Uni) but they are longer and not angled, both fit but I like the angle clearance better. Both come with mini filters for the jet/float vent hole.

I have stacks underneath, any standard size will fit under the filter as long as there is room for the 3/8" filter rubber mounting ring that fits on the stacks, here are the stacks on the old DCOE's before brake hose reroute:

3%2520Webers.jpg





Steve I just purchased a set of DCOM's and a manifold. Where did you get the foam air cleaners, and are there velocity stacks under them. Thanks Walter
 
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Stevehose

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Wayne: Pics coming tonight of manifold.

Bob: I feel there is a bit more torque as well as quicker throttle response because there is no waiting for secondaries to open and it pulls hard to the redline. Like you said, the audio enhancement definitely adds the feeling of more power, how much exactly is hard to say since I am stock otherwise. But accelerating is a lot more fun hearing the wail. I toyed with gauge panel placement also, I saw both versions (single on top vs. bottom) in various old Alpina pics but I decided to keep the non stock looking one lower in sight than the better looking VDO gauges. I don't think one is more correct than the other. You may be able to get an analog gauge by itself, just read the AFR output voltage specs of the sender unit and match with the input range of the new gauge.



That is neat and tidy installation Steve. This turned out to be quite a journey. How do you describe the change in throttle response and top end with the webers? If you can filter out the audio enhancement, do you feel you have gained much HP?

I bought the same gauge panel as you and was playing around with it last night. I am torn between this location vs under the radio. I thought I'd orient it with the central gauge on top rather than the bottom. I have a bit of a busy looking AF gauge unfortunately. (in inventory since the insurance company banned SC in my Miata), It has a digital readout.

Do you have a fuel pressure gauge on your car?
 

wmnewlife

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triple webers

Steve, yes I did get them from alfa 1750 and the manifold from JAM Engineering. Any help in installation would be greatly appreciated, although the bodywork has just been started, so it will be a month or so before the mechanicals go in. As an aside, when I was in college I crewed for Paul Spruell at a race in Savannah. Had to change a tire with a 4 way lug wrench. Early 70's and a small budget. How times have changed
 

Stevehose

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Paul's company was very helpful and willing to go out of their way to get the filters to me. I ended up using .55 idle jets with the inside bored out to 3/32" and 2 x 1.2mm air bleed holes. I made a set of 130 main jets also. This is for DCOM only as the idles and e-tubes are connected and not applicable to DCOE. I'd be happy to make a set up for you if the stuff you were sent runs too rich. Then you can tweak from there if needed. PM when ready if you need anything else. I also linked all manifold vacuum fittings together and run dist advance from that. Will the carbs clear the thermostat housing with that manifold? If not, adapting is in order.

Steve, yes I did get them from alfa 1750 and the manifold from JAM Engineering. Any help in installation would be greatly appreciated, although the bodywork has just been started, so it will be a month or so before the mechanicals go in. As an aside, when I was in college I crewed for Paul Spruell at a race in Savannah. Had to change a tire with a 4 way lug wrench. Early 70's and a small budget. How times have changed
 

Stevehose

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Wayne, here are some pics. Above:

IMG-20130402-00340.jpg


Angles to the left to clear thermostat housing:

IMG-20130402-00341.jpg



Angles up to give booster clearance and it can probably easily fit at least a 70mm trumpet:

IMG-20130402-00342.jpg



Nice.

Steve - Can you share a picture of your manifolds from the front (or rear) of the motor. I wanted to see the shape of the VGS one you have. I have seen pictures of the manifolds, but never mounted on an engine. Does the carburator air horns still interfer with the brake booster?
 

waynesie

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thanks for the pictures. Very sharp looking.
How is the clearance on the brake booster with that manifold?
All of the carbs are offset back from the head ports. Does this help with clearance of something?
 

Stevehose

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See the captions between the pics, I think I answered your questions, if not, there is room for at least a 60-70mm trumpet before hitting the booster, scroll down to see the pic with just the trumpets on, those are 60mm. The front carb manifold angles rearward to clear the thermostat housing and the others follow in order to maintain clearance for each carb's linkage.


thanks for the pictures. Very sharp looking.
How is the clearance on the brake booster with that manifold?
All of the carbs are offset back from the head ports. Does this help with clearance of something?
 

waynesie

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Thanks for pointing out the captions. I was so excited to look at the pictures I completely missed the words.
 
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