Stratos engine installed, have carb questions

Last week I sucessfuly installed the Stratos 4 valve engine back in the Dino. The Weber carbs 44 IDF-27 that came with the engine have the jets that were used in their rally events. I know that this is not going to be the best for street driving. Chokes are 36, Aux venturi 4.5, main jet 150, air correction jet 180, emulsion tube F11, idle jets 55, idling air jet 115, pump jet 40, needle valve 175. Any suggestion will be appreciated. I am looking at replacing the original elect fuel pump with a Carter P4070 with 4-6psi and 72gph flow. Has anyone used this fuel pump?

 

Photo's please of the installed engine, wll done.

 

Suggestions:

Use a Pierburg fuel pump, does not need a regulator, recommended by both Pierce and Norwoods, available through Pierce and Pelican. Lower current draw, smoother delivery.

Assuming a 400cc cylinder, 4v head, for STREET driving:

Would start with a :
34mm venturi - will pick up huge gobs of streetability, smoothness and response with only a minor loss of ultimate top end power
4.5 aux venturi is good - the height keeps the end above any standing waves.
idles - keep the 55s, may could get away with a 52.
main - go to a 145, 140 if it tolerates it without a transition lean spot
Keep the F11
air corrector to 190/200
keep the 175 needles, but REPLACE them if age is unknown.

All parts available from Redline or Pierce

Good luck!!!!
Look forward to hearing the results!

 

Do you have any idea what cams are installed?

 

Stratos cam timing specifications for this four valve engine are: Valve lift .360 degrees, duration 274 degrees both intake and exhaust, duration at .050, 252 degrees both intake and exhaust. intake opens 21 degrees BTDC and closes at 51 degrees ABDC, Exhaust opens 53 degrees BBDC and closes 19 degrees ATDC

 

The Carter 4070 is popular with lots of aftermarket carb applications. Doesn't make all the racket the Facet pumps do. They flow enough for Cobra kit cars.

 

...and the Pierburg is even quieter than the Carter - I've had Facet, Carter and Pierburg pumps. The single Pierburg is currently keeping up with 4 44DCNFs on a 3.2 QV Ferrari V-8 showing about 320 hp.

 

Interesting. The only photos that I have seen of a Dino with a Statos engine installed showed an engine deck lid that had a raised cut-out over the carbs to clear them. Were those photos of your car?

Mark

 

Photos please!

 

http://www.ferrarichat.com/forum/showpost.php?p=136152933&postcount=1

 

Is this the same car?

 

I would doubt it this an old link.

 

As I recall the Stratos engine had a bit more horespower than our pedestrain version.

 

I also think that it doesn't suffer from fuel starvation on left-hand turns!

 

As I understand it, it uses different carbs with a different float design.

 

http://www.ferrarichat.com/forum/showthread.php?t=72629&highlight=stratos+induction

 

We're not talking normal Stratos engine here. The road Stratos was probably the same as the Dino. The Rally/Group4 Stratos originally had 2 valve modified engines up to about 250 (real) bhp, but then the ultimate was this 4 valve engine usually quoted at around 280bhp in rally trim. I've seen a 4 valve race version (fitted in a 206S replica) putting out 300bhp at the rear wheels.
The same heads were also used on the 1976 2 litre F2 engine (using the old production 206GT block)and were said to produce 310bhp at 11,000 rpm on fuel injection.

 

The Stratos Stradale (what you call normal) was marketed at 190bhp, 5 less than the Dino. It couldn't have been otherwise or Enzo would not give the engines to make them.
However the cam profiles were different (more low end torque) different carbs and inlet manifold were used (as stated higher in this thread) as well as other less significant differences as compared to the 246. Most of these were targetting the FIA homologation in order to allow more room to play for engine development.

 

I mentioned the Stradale in the context of the fact that it's a 2 valve engine as opposed to the rare & fantastic 4 valve that's being fitted in the subject car of this thread.

You're absolutely right about the carbs and manifolds being different between the Stradale & the 246. It would seem as mentioned in one of the links that DCNFs were used because they're more compact to fit under the engine cover, but what a crap idea since it leads to the engine cut when cornering due to offset float chambers, whereas the taller IDFs have a central float chamber and keep running.
Where do you get your info on the cam profile differences? I'm not saying you're wrong, but I would like to know more. Interestingly the Stratos FIA Homologation forms list the cams as having exactly the same lobe heights as Ferrari quote in the 246GT workshop manual (36.7mm intake, 36mm exhaust).

 

I don't think it's been mentioned but some of the Gp4 cars had magnesium 'crossover' manifolds which gave straighter & longer tracts & set the carbs up even higher. Here's a picture of the 48IDFs on this manifold in my car. They stick up so far that the engine cover needs setting open when the airbox is fitted.
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Most Stratos victories were achieved with the 2 valve engine. The 4 valve was banned by the FIA as of 1978 as were multi-plate clutches and dog-engagement gearboxes.
Only factory cars were fitted with 4 valve heads before the ban.

FIA does not care for cam profiles and valve lifts, these are only mentioned in the homologation sheets for information and teams are free to use what they deem necessary.
The engine power delivery in the Stratos, especially the torque delivery when plotted against rpm, clearly differenciate as compared to the 246.
Check the workshop manual for the Stratos which has the plots available.
Post the 246 cam timings and I will post the Stratos ones if interested.

On a side note I consider pure folly to fit a 4 valve engine to a 246 given the rarity and pedigree. These heads were made solely for racing purposes and as such have not been engineered with durability in mind. I know of many Stratos owners who remove the 4 valve engines and use 2 valve ones to use their cars while the 4 valve ones lay comfortably in their living room.

 

Cross manifolds were only an experiment. They were never really used as the gains they brought were insignificant when taking the added complexity into consideration.

 

It turns out the documentation states the same valve timings for the Stratos. This could be so.
Maybe the different values for engine power and torque are only down to the modified manifold, carbs and velocity stacks (which are higher in the Stratos as compared to the 246).
It makes sense.

 

I agree - the longer tracts should give better torque