Dino engine characteristic

<My engine bucks sometimes at low rpm(1000-2000rpm) if I hit the gas too fast, normal for carburetor?

No. Your carbs are likely out of balance. Low RPM flat spots are the symptom; at higher RPMs even badly balanced carbs smooth out.

<Stumbles when taking left corners, some missfire(poping) going up hill. Common?

Might be common but isn't right. Sounds like a fuel pickup problem. That might also explain why high RPMs don't sound so good. Here's a test: warm the car up and in neutral rev to redline. This uses way less fuel than driving at the redline. Does the engine sound better? If so, check your fuel filter, pump and line.

Ken

 

The stumble is normal.

The carbs were designed for an engine that was mounted north-south, in the fiat Dino.

When they turned the motor a quarter turn, and mounted it longitudinally (sp?) it created this problem. It is something you learn to live with in a Dino.

My engine is very strong about 3500 RPM to redline. Doesn't stumble at low rpm, but you do need to give it a little gas when you take off.

Sound like carbs are out of whack, but could be a timing issue also. Remember the timing is two stage in these, and advances coming off of idle.

Ray, when you had all the work done, did you get the distributor checked? There are two weights in the distributor, and they can tend to get loose and sloppy with age, afftecting timing.

Might want to consider a rebuild. Not very expensive, parts under $200, and would probably make a world of difference.

As your car is Euro spec, the timing issue is easier to address. Your distributor does all the timing advance. US cars have a microswitch that does some of the work.

DM.

 

I agree with DM, the stumble is normal and part of the character of the car

 

DM - I found you comments interesting, and have a few questions. Your observation that the engine was designed for the Fiat 1) is not consistent with the production dates of the first 206 and the Fiat Dino occuring at approximately the same time and 2) raises the question of carb-induced hesitation on braking and accelerating in the Fiat with the engine mounted for-aft.

The introduction of the Dino engine into the Fiat (1966) was necessitated by Ferrari's need to produce 500 cars with this engine during the previous 12 months (homologated). Furthermore, it would seem a rather mundane engineering exercise to design carb floats that were impervious to lateral G forces.

Expanding on the 2nd item, if one suggests that the hesitation on cornering is due to the orientation of the carbs, then for-aft acceleration/deceleration should create the same hesitation when the engine is mounted for/aft. Am I missing something?

Jim S.

 

No. The flat spot is common, but not normal or unfixable.

Dino's have really aggressive cams with lots of overlap, meaning some reversion of intake is the norm, but the flatspot can be tuned away.

There could be any number of problems. Firstly, the ignition timing of a Dino is very important. They LOVE more advance at low rpm but keep it to 40 deg MAX, to do this you need a simple mod inside the distributor. They need to run at least 15deg static. 18 is ok, but as said. 40 Max, and use good fuel..98RON with a splash of LRP every now and then.

Carbs....

Float levels firstly. Set them properly by an experienced weber tuner. Also, make sure progression drillings are all clear and jets are clean/correct sizes.

I'd advise do a full engine service....valve clearances, chain tension/replace and re check cam timing. Build distributor with new points and condensor and modify the advance curve as said. Check the inlet for air leaks, use a new air filter and do float levels and carb checks as necessary. maybe even rebuild the carbs with sealed spindle bearings to remove all air leaks.

Dino's are the sweetest cars of all. When right, they are hard to fault.

I just finished a service on one this week, and it's a gem to drive....If only they had 300 BHP.....

 

I encountered this discussed in some Weber technical manuals when converting my car to DCNFs. The DCN series (including the DCNF), as many Webers, are designed to be installed with the float chamber facing the front of the car. If you look at many V-12 and V-6 front engine Ferraris, as well as the V-8s, you'll see all of the float chambers are forward. This positions the internals to best cope with most common 2 axis accellerations and fuel sloshing. As stated before, float heights play a part in this.
Yet another technical tidbit.
best
rt

 

Yup, what Russ said.

I've been working with my mechanic to alleviate this too. We're installing a European model distributor to work on timing advance, and we've tweaked the floats a couple of times to help alleviate it.

However, in a review written on the Euro spec car in a magazine in '69 (I'll dig it out and quote it exactly) it mentions the turn/stumble phenominon.

 

If you remember next time you talk to your mechanic, would be interested in what you found a good float height to be. I think stock is around 48 - 50.
many thanks
rt

 

The ONLY solution to alleviate the fuel starvation problem of the DCNF carbs is to fit IDF ones on an appropriate (i.e. Stratos) manifold. These manifolds can be had in Europe (Italy) for approximately 1000 euro.
Fitting DCNF carbs in the Dino was an engineering mistake that was carried out throughout the Dino (206-246) series for reasons I fail to understand.
Setting up float levels will only hide the problem in less than optimistic driving situations.

P.S.
Note that the manifold + IDF carbs might be more than the engine lid can take height-wise. A modification of the engine lid, possibly making a new one if your body builder can handle it, is part of the solution.

 

All good if you are driving your Dino and don't care about resale. Here in the states, a modified Dino is going to fetch a lower dollar than a stock one. So, if you don't want to show the car, and don't want to sell the car, it might work, but in the real world, it's not a very practical solution to an age old Dino problem.

 

To those who do USE their cars this is a major problem.
Solving it allows you to enjoy what the Dino is all about.
You can always keep the original parts and sell whatever is additional separately for more than you've payed for.
Don't know sound like a good plan to me....

 

I put 3000 miles on mine this summer, so I use mine pretty regularly.

I'd rather work with the issue than bastardize my car.

DM

 

Ferrari commited a HUGE mistake with the carb setup which was subsequently corrected when the engine had to face competition requirements.
It is not bastardization, quite a violent term, but rather correcting a notorious issue. You simply cannot address this otherwise and I chanllenge to tell me in what manner the DCNF carbs can cope with lateral acceleration without suffering fuel starvation. It's a desing issue, suffice it to look at them and realize they just can't perform correctly when faced with left hand turns...

 

I sit in the middle of this discussion, I certainly don't believe that swaping carbs is a "bastardization" of the car but I am not sure the carbs need to be swapped on a Dino. I happen to believe that as technology changes there is nothing wrong with improving the driving experience of a car, IF (note big IF) it can be done with no permanent modifications to a car. I would never make a mod to a car if it required cutting, drilling, welding but a carb swap does not need those things and if the new carbs can make the car run better, then why not.

I have not driven a F-car Dino that much and it has been 15+ years since I did, but I have put 4,200 miles on my FIAT Dino since August when I got it running. The FIAT Dino has a slight stumble which I don't believe is any less or any more than a F-car Dino, that stumble is something I will live with as it is very minor in my opinion. If you think a Dino has a bad stumble, come on over and drive my 1934 Singer Le Mans and trust me, that Dino will seem like a modern luxury car. I guess, I can put up with some minor things due to the cars I own, 2 1930'e era cars, 1 1950's car and then my Dino and my modern car. These Dino's are not the fuel injected ultra smooth wonders of today, they have some idiosyncrasies that is what makes these cars fun to drive.

By the way, I am well aware of the controversy of the 246 with it being called a Ferrari or not, I don't want to get into that discusion, I merely called it a Ferrari Dino here in this message to differentiate between the 2 Dinos.

 

If the carb swap requires a modification to the hood to make them fit, then that clearly changes the outward appearance of the car.

I'd call that a bastardization for sure.

If you have to swap the intake manifold, to make the car work better, that too would, at least in my book, qualify as an unreasonable change to the car.

Either would obviously cost points at a concours, and as I'm considering that for my car, make these kinds of changes ones that I wouldn't consider.

If you want to drop probably $6K into the car to get rid of a slight stumble in left hand turns, that's fine, but I'm gonna pass on this mod.

 

The Lateral acceleration is not a problem. The Floats on a Dino face Fore and Aft, while on a 308 they are left to right.

On a 308, the lateral (left to right) acceleration / cornering force is a problem, and yet it can be minimised or even removed with tuning properly.

On a 246, the acceleration problem, if any, is from LONGITUDINAL acceleration, as you pull away from standstill at very low rpm.

The flat spot comes from ignition timing and NOT fuelling. The flat spot is INSTANT, whereas if it was fuel it would take a few rpm to happen while the float chamber runs dry (like a 308).

Dino's in stock standard form can run PERFECTLY with only a small modification to the internals of the distributor.

 

I'm sorry but what you're saying here is wrong. The Weber 40DCNF carbs fitted in the Dino have their floats in the middle of the carbs but eccentric to the left. This is a non-issue for longitudinal applications for which they were designed. However when fitted transversally the eccentricity of the float chamber to the left of the carb body makes it prone to fuel starvation BY DESIGN. These carbs are not supposed to be used in transversally mounted engines, such as the 246 Dino, as opposed to Weber IDF carbs.
Ferrari have used the Dino engine in competition prior to fitting one of its derivatives to the 206-246 series. However ALL competition applications used the engine LONGITUDINALLY.
I guess that no one saw the gremlin but I'm amazed as the 2x6 prototypes must have been tested under harsh conditions where the problem is more than obvious. One excuse might be the fact that most tracks, and Maranello in particular, have predominately right hand turns but this is insufficient to explain such a big deficiency.

As for the 308 is uses different carbs and they are mounted inverselly as compared to the Dino hence no problem.

 

There are also some different floats for the Dino that were supposed to minimize the stumbling problem. They were black plastic as opposed the the stock brass ones. I haven't tried them yet but the stumble is just a little annoyance to me. All cars have their little idiosyncracies. Unless you are racing I would just live with it.

 

my engine runs the best from 4k-6k. Certainly the engine will run up to redline at 7800, but at above 6800 it seems to not enjoy time up there with a smooth but stressed sort of sound. I have the left corner starvation issue as well. I don't have any other flat spots or lugging issues from 1k-4k.

 

Dave, I agree, if it requires cutting of the hood, this is wrong and is a mod I would never make as I stated with no cutting/drilling/welding.

Now, IF the problem with the Dino is due to the lateral mounting of the motor, then how do you explain the FIAT Dino having the same problems ? That motor is North/South in the car and the FIATs also have that stumbling on acceleration from idle and starvation on fast corners. I think it is just a design issue and you love these cars for what they are and drive them or get something else. But since with minor tuning mods it can be greatly diminished, why hassle with changing carbs.

Of course I only know about it from the view point of the FIAT Dino but Palo Alto is only 6 hours drive from me and I am driving up to see that ebay 246GTS on Wednesday, maybe the test drive will prove me wrong and its worse on a 246, I doubt it. I am not ready to buy one yet but its too close to me and too nice looking to not consider getting it and I have the wifes permission. What a xmas present it will make

 

If you're using the antique Dinoplex ignition your spark will not be able to follow above 6000-6500rpm. This is bad for your engine too as partial combustion and irregular spark will clog both inlet and exhaust ports/valves.
The Dino produces its maximum output in standard guise at 7000rpm. This is where you should shift to obtain maximum torque in the next gear (@5000rpm). The only problem is the Dinoplex igintion will not let you get to 7000rpm properly.

 

This is not absolutely necessary and in any case you would NEVER drill/weld the original cover. If necessary there are artist bodyworkers that can make new ones out of aluminum sheet that are 1" higher and nobody can ever tell they are not original. I can provide pictures if you wish of several 246 with these engine lids.

The FIAT Dino cars DO NOT have this problem, period.

 

That is great news, I will have to tell the FIAT Dino owners club that we don't have the problem we all think we have.

 

No you should tell the FIAT Dino owners club to have a look at the application guide for Weber carburators. They might then find out, at their surprise, that the carbs used in their cars are perfectly fitted for their application.
Failing that you might suggest to your fellow club members that they should start looking for someone who know how to tune Dino engines properly.

Cheers,