Weber carb installation on QV/3.2 summary

Since the loss of the photos in the old board and a few recent requests from new folks sparked by the frenzy in modification posts, here is a brief synopsis of putting 40 DCNF Webers on a 3.2 for anyone that is interested.

My reasons for doing this stem from a lifelong love and association with these magnificently elegant carbs on Alfas, improved long term reliability, the elegantly simple DIY repair requiring no special tools with the improvement in power, throttle response and sheer personality from retrofitting the classic Ferrari OEM induction. This is not an original idea of mine, as the Porsche 911 community has been retrofitting Webers to Bosch K-jet cars (2.7 and 3.0 liter) with great success for years.

The key parts are four beautifully cast manifolds that fit the 3.0qv/328 head from Frank Capo of Modena Engineering in Australia. I know both Carobu and Durable1 both do business with him, but I found my manifolds at Blackhorse. Be sure to trim and match the stock gaskets to the intake ports. Only a small vacuum tap was needed for the ventilation control system, as the Mondial’s ABS brakes do not require a vacuum line in this application. Everything actually just bolts up like it was original.

Four new commonly available Weber 40DCNF-12s were purchased as well as the large Facet fuel pump used as a replacement for the Ferrari Corona unit. I will make a VERY VERY long development story short by saying one right answer is setting up the Webers with 34mm venturis, 135 main jets, F24 emulsion tubes, 190 air correctors and 53 idles. It of course depends as well on what cams, air filter and exhaust you have. Stock K-jet cams were used, as well as a stock early 308 airbox, which bolted right up (Frank Capo is a genius), and a custom free flow exhaust was fabricated using a Dynomax muffler and four Ferrari Daytona resonated chrome tips. The last bugaboo, the linkage, was fabricated with parts from Pierce manifolds and original 308 carb arms. the side scoop was cut and modified to allow a cool air duct to the airbox.

Best chassis dyno numbers obtained (although with 36mm venturis) was about 242 rear wheel hp, which with common 17% loss correction places it at about 290 flywheel hp (Factory rating of 260). The sound of the 3.2 liter 4 valve engine with Webers is simply not comparable to the original Bosch K-jet injected version. It is a magnificent awe-inspiring sound.

This is a very easy retrofit to do for an amateur, requires no special tools, and really adds to my enjoyment of the car.
Hope this is entertaining for some.
best
rt
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Philip,
Yes, I had looked specifically at the TWM and spoke with them at length - great helpful folks.

For what I wanted to do, the Webers were thousands less and easier to install, offered a much more simple and maintenence supportable system and gave about the same results through reduction of flow resistance inherent to the K-jet as the throttle bodies. While I'll happily concede the overall versatility to any good EFI, for what they are, Webers are a quite elegant piece of kit, and quite reliable.

If I were going to the cost-no-object nth degree would unhesitatingly go TWM for that last 5 %. With the deal I got on the new-in-the-box DCNFs (Four for $1K) and sheer simplicity of install, set-up, reliability and maintenence (I'm no Mark E. ), I did ok.

I must confess also a less objective component of passion and the 'rightness' of a Weber carburetted Ferrari did weigh more than a bit, and is perhaps tied to my 'more historical' age demographic. The emotive personality and total Italian driving experience they give the car is sheer joy to me as it was with my old Alfas. Like Peter relates, it's difficult to objectively explain dispassionately, but there it is.

best
rt
Apassionato e Tifoso
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OBTW
Was not neccesary to hook up the starter enrichment at all, as starts fine with two shots of the pedal, even in sub-freezing. Most 308 guys say they never use this anyway.
Need to bypass the fuel pump relay to provide power to the fuel pump from the moment the key is in the 'on' position. Easy.
The fuel system basically duplicates the 308 GT/4 return flow loop system. No expensive high pressure pump or accumulator needed, but keep a high quality in-line filter!
best
rt

 

Many thanks. I am quite proud of it.

Yes - since the K-Jet and Marelli ignition are separate, the stock Marelli Digiplex or Microplex ignition can be used without modification. The set-up dynos were done with the Microplex in place.

The Mallory Unilite/MSD single distrubutor conversion seen in post #5 came a bit later as I tired of the Marelli stranding me with THREE separate single bank ignition failures. The whole conversion with a new Unilite distributor was done for less than the cost of two stock Marelli distributor caps, is totally user adjustable, has widely available inexpensive replacement parts forever, has MSD and is now bullet proof reliable. Peace of mind at last.

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rt

 

This car, or 3.2's in general?

In general, if you like the high ripping metallic sound of modern F1, my experience with this car is that a tubi best approximates a modern F1 sound.
Currently, this car has a bespoke open free flow system with dynomax and ansa components (after much experimentation) - this gives a more classic and older Ferrari style sound.