Hi, Although the chokes aren't connected on my Daytona, they are all still on place in the carbs, so would the accepted wisdom suggest that I remove them and keep them somewhere safe, just in case I want to reinstate them, or should I leave them alone? Paul
Remove them, the engine will breathe better, and put in a box ...doesn't even have to be safe... You will never reinstall. Regards, Alberto
Personally, I’ve never fully understood the aversion to chokes. Yes, if they are malfunctioning, or not used right, bad things can happen (and I understand the peace of mind that can come from disabling them), but they were included on cars for a reason (a dead-cold engine is never going to start/run as easily as it would with the chokes engaged). Also, at least on a Daytona, the design of the chokes really has a lot of clever aspects to it, and I find them to be interesting to show to people. Regarding “saving them in a box”, I wince then I hear people say that; the number of such “boxes” that get separated from their cars seems to be substantial in my experience… Finally, if the chokes were installed properly, removing them while the carbs are on the car will not be for the feint of heart (folks make the choke-plate screws super secure, so that they can’t vibrate-off and fall in the engine).
The cars were originally designed to run in a much wider range if temperatures than they’re likely to encounter as cherished classics, and a couple of prods of the accelerator prior to starting generally works fine. Paul
I don't disagree, but "generally works fine" if not used at "wider range of temps" is not the same as "works as well as their design allows". I don't see the big advantage in removing them, and leaving them potentially saves the next owner a lot of hassles; as well as saving the current owner the hassle of removing them...
I was simply asking the question. So far the responses are equally split between leaving them on and removing them. I have only had the car a few months and I haven’t yet had the opportunity to use it in anger. With a couple of pumps of the accelerator, it starts easily and soon settles down to a tickover. However, I’m pretty sure it is running rich, so I don’t know how easy it will start once the carbs have been properly setup. Thank you for your input. Paul
If someone will be tuning your car and setting up the carbs in conjunction with the distribution timing. I suggest you should discuss these issues with that person who I imagine would be a specialist with experience on the car.
All specialists will have their own opinions, but I generally find that the collective experience of owners tends to be more reliable. Thanks, Paul
100% correct. How much would a Daytona today be worth if over its life someone took off all the parts they didn't feel like dealing with and threw them in a box and the box is long gone? Its happened 1000 times and we know exactly the correct answer.
I own a heart and at a complete loss to povide any useful advice on heart surgery. Ask a knowledgeable source.
To be fair, there are quite a few people on here with huge experience, yourself included, so I include all of that in the "collective experience" I was seeking advice from. I was intruiged by the comment "Also, at least on a Daytona, the design of the chokes really has a lot of clever aspects to it, and I find them to be interesting to show to people." Could you enlighten me as to what the "clever aspects" are please, because they may well persuade me to fully reinstate them, although when my car was restored, they neglected to install a choke lever. Thank you, Paul
I never said that. Maybe ask the person who did. My experience does tell me cars that are complete and have not been misguidedly stripped of parts who some may have misguidedly considered superfluous are far more respected, prized and valued. We went through far too many years of seeing parts of that description taken off and lost to even consider learning the same mistakes yet again. The presence of the chokes does not diminish performance.
It was my comment. If you look at them, you would see that they work the throttle plates along with he choke plates, and as a consequence they are sort of like a hand-operated throttle control with very fine adjustment. The choke plates are also sprung, so that (1) they can close over a range of throttle settings, and (2) they can automatically open in response to the engine being able to sustain running without them. The amount that the choke plates can open by themselves is not huge, but fine if one is just idling. Even the screw/nut that the choke cable runs through is neat; the nut presses against the cable only, and thus leaves the screw free to rotate relative to the control lever that the cable pulls. Most choke systems are not as cool as a Daytona’s. I hesitate to make comments about carb tuning, because my Daytona is the only Ferrari that I have tried to tune the carbs on, but when I got it, the car started surprisingly well without the choke, but ran really rough at hot idle. Turned out that someone had adjusted the carbs to run really rich at idle, which was great for “cold start” appearances and short test drives, but once the engine was fully up to temp (maybe 90C on both coolant and oil) the mixture became so rich that some cylinders were not able to fire any more. To get the car to idle well at full temp, while starting without the choke, I found that the choices were either have it idle really fast when hot, or to hold the throttle partially open for a few minutes when dead cold, and then live with a rough idle (due to low speed, and some cylinders being a little too lean) until it warmed a bit. I don’t claim to be any expert, but given how petrol volatility and air density vary with temp, the above seem expected to me. The chokes basically drop the pressure in the carbs to “simulate” the effects of higher temp, and thus, get around the leanness that would normally happen when an engine is cold. To me, they are just part of a properly operating car (as evidenced by the instructions right in the Owners Manual).
When a car has trouble starting when cold, it is because the cold air is too dense (lots of air molecules in a given volume of air), and the petrol does not vaporize as efficiently (fewer petrol molecules are in gas state), the result is a lean mixture that won’t burn well. When a car is hot, the air going into the engine is less dense, and the petrol almost completely vaporizes, so mixture becomes more rich. By blocking the air flow, the chokes create a slight vacuum in the carb; air becomes less dense, and the petrol vaporizes more easily. So the chokes make the mixture more like it would be in a hot engine; this is what I meant when I said “simulates the effects of higher temp”.
I doubt that there will be any difference in performance if you remove the choke. Therefor I would just leave them as they are, assuming they are in perfect condition. Here is the data sheet of the Weber 40 DCN 21
Agreed "owners" was probably a poor choice of words, I simply the combined experience of those on Fchat.
Thank you. The carbs certainly appear to be in perfect condition and have only done a few hundred miles since being fitted, at significant expense.
It never would have occurred to me to consider any of that special or unusual. Most carb choke actuation systems also open the throttle plates as can be seen on many Webers, SU, Solex, Rochester, Carter, Holley, Ford and the many varied Japanese carbs. The cable attaching arrangement is not unusual either and was the norm in Weber carbs up to the time of the Daytona. Your last sentence I disagree with nearly 100%.
This whole thing has gotten off the rails. A "strangler choke system" like the Daytona and MANY other cars creates a vacuum at the auxiliary venturis, thus pulling fuel out of the main jets to enrich the mixture for cold starting. It, in no way, duplicates any "hot running" conditions. Most Weber carbs prior to the late 60s use a "fuel enrichment jet (starting jet) to achieve the same results. Weber used the "starting jet" system because it does not reduce air flow through the carburetor as a "strangler" choke system does. As time went by, Weber went to the "strangler" system because it was cheaper to produce, requiring less machining of the carb body itself. a good Daytona should ALWAYS cold start without using the "choke" with about six pumps of the throttle. We used to commonly refer to Weber cold start systems as "anti theft devices". If you wanted the car to NOT start, pull the choke lever.
Happy to stand corrected. My Daytona is the first carb car that I have worked on in probably 30+ years. My recollection of the carbs (Japanese stuff) on my cars way back then was that they mostly just had a temp-sensitive coil that just closed the choke butterflies; could well be that they all also opened the throttle plates, but that was at least not apparent to me at the time. Thanks for setting me straight. Seems that your caution against listening to owners is well warranted...
You know, I had forgotten about the other jets when I was noodling about how the carbs worked. That would certainly be a lot bigger effect than the density and volatility mechanisms that I had assumed. Apologies to the forum for spreading buggy thinking.
