Carb Mondial update - a bit technical.

After many months, the ported big valve heads are on the Mondial. Norwoods is adjusting the springs/shims and dialing in the .360 lift cams today. I'll be in Dallas tomorrow to re-cam the accellerator pump on the new Weber 44 DCNFs which will be replacing the tried and true 40s I've used for several years.
One major goal of this car was to be simple to set up and maintain, long-term reliable and a solid bottom end.

After talking to Mark, he's convinced me to go ahead with the 38mm main venturis off the bat instead of the 36mm I had planned as an initial guess.. I am also going to the very husky -12 accel pump cam, which Weberphiles would be interested to know requires a different lever mechanism than the smaller -11; Jetting will be based on some existing Weber charts as well as a lot of Dynos before - but still its much a wag as so much is different: increased compression, ported heads and a bigger carb to name a few. We'll start with approximately a 150 main, F24s and a 190 a/c; I do think 50 - 53 idles should be sufficient. Flow is going to be up roughly about 10%+, with much occuring at low lifts with th the porting and larger intake valve (larger than a 348 valve, obtw). Measured charge velocity is also way up, so with the new 10.5:1 compression ratio, medium duration cams, and the honkin' -12s, the throttle response should be a kick. The exhaust side stayed about the same, with just some mild clean up and stock valves. We are also going Euro with Tubi ceramic coated headers (very nice) and a true dual bespoke s/s exhaust which should help the flow. I am splitting each side into two paths with two resonant mufflers apiece, timed to interlace the pulses through the four flow through mufflers.
I'll keep the previous bulletproof reliable ignition we had, which is a single Mallory Unilite electronic distributor, with about 34 degrees advance all in by around 3000 rpm or so.
The a/f will be set by dual mixture O2 sensors on each side with a LM-1, then we'll go to the dyno.

Details for reliability also include a Pierburg fuel pump, all new hoses and a high torque starter - am thinking about an up-rated alternator as per the Consjero installation.

A bit more classic Italian Ferrari set-up with big Webers rather than the blown turbo/superchage guys, but is really fun and sounds great. Pictures tomorrow!

Most importantly - I am waiting for the up-rated fuse/relay box

 

The bench flowed about 108 - 109 after an initial of the low 90s. As most know, this is just the peak flow number; the total charge is an integration/summation of all of the flows generated at lifts from open to close. With a very strong increase in low lift flows, I am hoping for a large increase in total intake mass. Another constraint was charge velocity - in carburators, this is part of the 'signal' that the carb sees to respond. While not as important in injected engines, high flow velocities generate excellent carb response.

It's this high velocity and flow coupled with the 10.5:1 CR that I am hoping gives me an even more improved throttle response - thus my recent move to the larger accell pump cams. The ignition advance will already be full in by 3K rpm, so with the moderate duration higher lift cams the umph when you dump the throttle at 3000 rpm should be very improved. The 911 guys that convert from CIS to Webers talk about this improved throttle response: it makes a 25 hp gain feel like 50.

And then there is the sound and personality of a Weber carb'd Ferrari - very subjective but a large part of the car's appeal for me.

And best of all, it will still look exactly like a Ferrari engine and be very familiar to maintain by any Ferrari mechanic. This was one of the reasons I did not go to shim-under cams. Much like Pizzaman who faced the same decision, the DIY maintenence / reliability were equal criteria to performance for me, so th stock shim set up was retained, limiting my safe long-term lift to about .360; near stock durations were kept to maintain a rugged lower end powerband. With a car weighing well over 3300 pounds, it needs the most grunt it can get.

Although in a couple of Weber specific threads, attached is a photo comparing the 40 DCNF which I've been running for 7 years with the new 44 DCNF showing the much larger butterfly area. Also attached is a schematic of the experimental muffler system utilizing four smaller s/s mufflers and taking advantage of harmonic silencing and maximizing the silencing volume seen (taking advantage of the flat crankshaft alternating bank firing) and still keeping a true dual system.

Hope this all works!
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Great to see everyone at lunch today!

10.5:1 short block done, placing valve springs/seals today. After consideration, rejetted carb and rebuilt accellerator pump with the larger pump cam. So, here's the going in settings on the 44 DCNF:
38mm primary venturis, maximum available
Changed from 3.5 to the taller 4.5 Auxillary venturi to ensure a strong vacuum signal to the mains at mid range rpm
Idles changed to 52
Running jets changed to 145, F24 and an a/c of 170; Will have a 150 available as although flow/velocity is up. the new larger venturi will 'dilute' that signal.
In addition to the larger pump cams, the accell discharge jet was set as 35.

Here are some photos showing
side by side comparison of 34, 36 and 38mm venturis
3.5 and 4.5 aux venturis
small and large accell pump cams
new ceramic coated tubistyle headers - these photos do not do them justice

Will get the heads on the next days; more photos
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thanks!

I also got to compare the new bigger intake valves that were installed as part of the porting job. It is a bit difficult to see in the photos, but very plainly obvious in person. It is also apparant as the valve seat now very nearly goes up to the side of the chamber. Here are some photos, two with me holding a stock intake valve next to the new larger valve to show the difference.

As always, thanks to James, Mike and Andy at Norwoods - they are terrific.
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Other tweaks

We also decided on adding a couple of more tweaks to the car today:
1. convert linkage from the current side pull to a center pull bell crank similar to a stock 308
2. rebuild the alternator using the current housing to the max available amperage
3. convert the tach to a standard 8 cylinder tachometer. I had been using the previous microplex box simply to run the tach, but will now take the signal off the MSD. Anyone need a Microplex computer for $1K?

Other previous tweaks:
WEBCAM High lift intake cams (.360)
Gustafson High torque geared starter
Pierburg fuel pump
high flow airbox and side scoop mods
Mallory Unilite distributor/MSD 6AL

 

Looking like two weeks, Dyno in three to four after break in.

Oh, and am also getting a new high pressure kevlar clutch.
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As odd as it may sound, check with the boys at Ferrari UK - they've come up with some oddball Weber parts for me before when nobody could get them. As the F24s you rightly seek were standard equipment, they may have a set...

AND, although I do not recommend them for street use, I could be persuaded to part with my set of rare 40 DCNF 36mm venturis for race prepped cars. As far as my set of 34mm venturis, I guess I may could part with them as well being they are for the 40 DCNF... these actually work well on the street for mildly prepared cars.

Which reminds me -- there will be quite a parts sale when I finish with my little black car: stock headers, stock starter, Microplex ECU etc...
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Many thanks - you "get it" with what this car is about, but I would argue that it is quite simple.

 

thanks -
I always knew that the linkage was a long term weak point in an otherwise solid installation. the 'twist' transmttied along the throttle shafts over time might eventually make it harder to tune with the slight 'progressiveness' of throttle opening. With center opening will be much better. I would also like to quicken the throttle response a bit by reducing pedal travel to WOT.
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That's what I am talkin' -- yours is soooooo cool.
We've got to modify the later water crossover to accept a pivot.


Very nice indeed. - by the way, which size throttle bodies did you use?

 

Heads are on the engine.

For other Mondial owners - it looks like we can rebuild our existing alternators to 100W using the same case, so I am pressing ahead based on my theory that a larger alternator will help.

Garage sale items also now include a set of 3.2 US exhaust headers, a factory starter and an ultra-rare Marelli Microplex ECU.

Pictures soon.

 

the ultimate 3.2 engine (at least for me) continues to take shape with the ported and polished big valve heads installed.

As some may remember the extensive cam saga from the other thread, the engine has the original exhaust cams and new higher lift intake cams from Webcam, .360 vs .348 with an improved faster ramp. The durations are near stock, as I wanted a powerband and torque that was realistic for a regular street used 3500 pound Mondial. The Carb venturi size and the cam durations have been matched to bring in max power just about 7000 rpm, which is what the car is geared for anyway. The cams were also matched to the tappet followers for maximum reliability, wear characteristics and keeping the original shim over tappets for ease of maintenance..

I have cheated a bit in modifying the functional final drive ratio by increasing the diameter of the rear tires (Michelin PS2) to give an effective 5th gear cruise of a bit over 21 mph per 1000 rpm as compared to the stock 19.8. Little different I know, but It was the easiest way to get some change. I also bucked the usual trend and went to a tire of moderate section with 205 in the front and 235 in the rear on 17" Speedlines with 7.5 and 8.5" factory recommended widths.

Will look at initial ignition advance at the stock 34 degrees or so by 3000 - 3400 rpm, being wary that I have raised the compression ratio from 9.2 to 10.5 to one. The ignition will be an MSD 6 AL running a very simple and reliable Unilite single distributor and MSD high energy coil. After having three Marelli induced single bank ignition failures, the first thing I want from an ignition is simple reliability.

As before, a 3-4 PSI Pierburg fuel pump feeds the four Weber 44DCNF with polished velocity stacks and 38mm venturis singing like eight Andrea Bocellis on an Italian
opera.

Many thanks as always to the folks at Norwoods and Webcam, and Mark E. for listening to me kvetch about head porting.

Note new big fat intake cam lobes in photo.
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Coming together - detailing engine subframe. Brembo drilled rotors, Koni aluminum adjustable perch coil overs with higher rate springs.
Engine together, passed leak test; 0.360 cams installed, 10.5:1 pistons, ported/polished heads with large valves, port matched manifolds
New 100+ amp alternator done.

Speaking of electrical, I did go ahead and have the tach converted to a standard 8 cyl tach which will be triggered by the MSD 6AL, enabling removal of the remaining Marelli Microplex ECU, harness and sensors (fewer things likely to break ) All now for sale, obtw.

Even though I am supremely looking forward to the 44 DCNFs, I must confess a wandering eye to the "other thread" with the brilliant TWM throttle bodies and wondering 'what if' ? Anyway, I'm in this for bulletproof reliability through elegant simplicity and have always believed Italian cars, advanced electricity and me don't mix well.

More this week - hope to get her started next week - then it continues to get interesting.
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Here it is, old school Ferrari on a 3.2 -
Install next week. Thanks as always to the great folks at Norwoods.
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