Kind thanks! Good reading material
"While cruising with my foot barely on the accelerator, it's very lean to the point of inducing lean misfire. If I depress the pedal a little more it richens up a good bit and stays rich depending on jetting, or goes lean depending on jetting. But as soon as I go back to 'steady' on the pedal just to maintain speed it goes lean. This is typically taking place under 3500rpm". I had the same exact situation last year. Every time that I barely depressed the accelerator, I would get a sneeze. We bumped the idle jets from 50 to 57 and the issue went away. Hope the 60s work out for you.
Dear John, We have been well behaved here waiting as patiently as we can. We need a video of your engine running. It could be a good for us kids to learn your techniques as you tune it in. It will also helpmotivate others to get their projects going. So pretty please John give us a video. Love the F-Chat kids
John just saw this. what are your cam timing and overlap? If you have a lot of overlap that would explain needing to fatten up the idles, esp. as the 36 mm chokes are in. Please ensure that all of your idle enrichments are closed as well. Also, what are you now running idle and full advance on ignition? Ferraris historically run happier a bit rich, and a bit rich also covers up other ills. I think your eval criteria are good, and remember that another factor is 'under load' and not under load as far as how lean one can tolerate. I know you know this, but you are setting up tuning as there is a season change and air densities and temp variations can also cause changes, and you have also probably seen that an air filter tends to make it a bit richer, so tune with an air filter on. will sit down tomorrow and think on al this bit more. Superb work on a wonderful car - she is a world class piece of machinery.
Russ, These cams are big things. Lots of overlap. I have .425 intake lift and 248 duration @ .050 while exhaust is .395 lift with 240 duration @ .050. Currently, I have 10 degrees initial timing with 35 total @ 6k. I'm sure I have a bit more at the top end though really. Keeping the air filter on for sure. So, once the 60 idles arrive I will do two things to richen up that mixture. Install the jets, and change the float levels from 48mm to 50mm. Changing float level will bring the mains in a hair earlier as well as fatten up the mix a bit. I set it at 48mm initially as I knew I was going to experiment with F24 emulsion tubes and from previous experience with them, they prefer 48mm for some reason. A note on F24 emulsion tubes. They seem to emulsify the fuel more in the mid range than the F36 tubes which run a more dense mixture mid-range and of course lean out at the high end. F24s are the exact opposite.
Reviewed some data quite a bit last night. Next setup will be F24/145 mains/200ac/60 idles. What's funny is this jetting option is very near what a bone stock engine runs well with. Staying true to the Bernoulli effect which in essence is the lowering of fluid pressure in regions where the flow velocity is increased. So it's safe to assume the engine is flowing a good amount more air at a greater velocity if near stock jetting has been retained yet the engine has been enlarged a good measure. Image Unavailable, Please Login
John, Silly question, maybe... you've got a 36-tooth wheel installed already. Why not rip all the jet stuff out of the webers, pop those 36mm restrictions out as well and install some shower injectors over the velocity stacks? Hooking up a TEC3, ViPec, Motec, Megasquirt or what have you is not a big deal, really. So much easier to tune though...
That's next on the list. I have not totally decided how I want to inject the engine, but that avenue of shower injectors is definitely being considered. The problem lies with fabricating a good bracket to hold the injector while fitting inside the airbox. I just don't want it looking lame.
adjustable cam gears arrived. Dave is an artist. These things are beautiful. Uses the stock belt Image Unavailable, Please Login
I'd be more concerned about airflow over the trumpets with a bunch of injectors hanging over them in what's already a rather shallow air box. Or alternatively, use these: http://www.burtonpower.com/tc42i.html (available in 40, 42 and 45 mm) They are a bit lower than the Webers though.
Yes, I like the Jenvey setup too. It's short and clean. Bolts right up to the existing manifold too. With injection, there is a small mountain to climb in terms of 'stuff' that needs to go on etc. New coolant sensors, air temp sensors, MAP, TPS, fuel pump, fuel hoses, tons of wiring, sequential sensor fabrication, and then the ECU has to be tuned according to warm-up phases, fully warm phases, duty cycles blah blah. It's literally a never-ending story of tuning. Very accurate, but labor intensive
wait a minute? what with all this injection talk? i thought the plan was to keep it looking stock with the dcnf's? with a stand alone injection, your drivability issue should disappear. i wouldnt mess with the shower injectors... way too much effort for a street car. WOT is where you will see the benefits of the shower injectors. once again ask yourself how much time are you gonna spend at WOT vs part throttle? Hell, even at a classic high speed race track like Le Mans have a few chicanes thrown in them decades ago to require much more part throttle input. The long full throttle blast days of spa and le mans are lone gone along with the old glorious P6 grind. For the last few years crotch rockets have duel injectors and gxers have trick duel throttle plates in each itb as well. one injector above and below the honda CBR while the Suzuki injector sandwiches the lower throttle plate with an addition throttle plate above to control part throttle velocity im assuming . what is really interesting with gxer is against conventional wisdom, the lower main injector is not pointing at the back of the valve head but nearly perpendicular with the throttle plate. i would guess program this raises exponentially with the extra pair of throttle and injectors for the hobbyist. The cam lobs are trick too but thats another story. Sorry for the spinning off a tangent. I hope you dont give up so soon on the webers. for what its worth, best regards hf
They cost a fraction of the TWM's... The shower injector idea is to keep things really simple - simply keep the webers (just don't feed any fuel into them), and have the fuel rails and injectors hidden away in the airbox. Looks just like stock, but has EFI. Nice eh? Plus it saves a LOT of horsing around fitting TBs, throttle linkages, intake manifolds... The Webers can (optionally) be gutted (remove venturi, remove main jets) in order to improve air flow...
you dont anticipate running problems with just a shower injectors over the a gutted dcnf? wouldnt you need an separate idle circuit? im confused. why wouldnt you gut the venturi's? they are a main obstacle in the intact. For me it wouldnt be an option. i do very much like the idea of hidden stock looking EFI. if you can run the fuel rails inside the valley of the motor you can still have a stealthy stock look with port injectors given the height of the standard airbox. I have heard of people have hidden injectors in weber bodies anyone have any pics?
I've always wanted to inject this engine with a nice large set of ITBs but I see it as a winter project for later. ITBs I think would allow me to get the absolute maximum out of this engine, which is really what I'd like. I'm not a big fan of off-the-shelf stuff like TWM, or Jenvey but rather I like the Ducati ITB or Hayabusa ITB route. Much more custom, but the cool factor combined with it just being better is great. At the same time, the engine drives just fine with the DCNFs, but that extra 5-10% I could from the additional flow a proper injection system would yield makes me sort of hungry for it! I'm amazed I don't have any transition stumble from the leanness I have with the DCNFs though. That'll be fixed with the richer idle jets though. Shower injectors are neat, especially the newer Marelli units which supposedly atomize better than any shower injector ever has. I don't think I would want to go this route though. Just to clear stuff up, this engine has zero driveability issues as it truly is a kitten on the street. Furthermore, this motor without a doubt drives better than any motor I have ever built. The Webers just need their jetting worked out and I have my hands wrapped around that well now. Otherwise it's better than I could have ever imagined. I was expecting at least a small driveability issue with these cams etc, but there is absolutely none as it honestly drives better at low rpm than any stock engine I've driven.
good to hear... if drives fine now it should be fantastic on a stand alone. looking forward to the post winter project. all the best
Carburetor jets arrived and I installed them, but I noticed the other day that my crank damper was a bit wobbly. So, I removed it and am having it reset/rebuilt to ensure near-perfect concentricity. Should be back mid next week. Not taking any chances.
By any chance can you measure for me the O.D. of the hub / pulley as well as the I.D. of the outer steel ring? Difference would be 2x the thickness of the neoprene bit. Thanks - DM
Dave, I'll have the rebuilder measure it while it's down. I think I misunderstood your meaning at first! Thanks for clarifying.
Great, thanks! Please ask your chappie if he could snap a picture of the mating surfaces of both the inner hub and the outer ring, corresponding to the surfaces that the neoprene isolation layer is bonded to, should these surfaces be anything other than perfectly smooth. For instance, might there be any grooves or keyways or anything similar like that, which the neoprene isolation element has to "bite into" on either of these surfaces? I'm working on a design for a DIY outer damper ring, based around an aftermarket aluminum hub / pulley (see picture) - thus the reason for my inquiry. Thanks and Cheers - DM Image Unavailable, Please Login
