Interesting Weber jetting

[hyper4mance2k]

I posted those weber emulsion tubes and for some reason they were shrunk down so small they are illegibal. Anyway have any of you used annular venturi's? I have read and heard some amazing things about them unfortunetly i have only found them available for the Weber 44IDF.
http://www.cbperformance.com/Jan2000.asp
http://www.speedtalk.com/forum/viewt...01f9ee77937530

[Gaz64]

Originally Posted by hyper4mance2k

I posted those weber emulsion tubes and for some reason they were shrunk down so small they are illegibal. Anyway have any of you used annular venturi's? I have read and heard some amazing things about them unfortunetly i have only found them available for the Weber 44IDF.
http://www.cbperformance.com/Jan2000.asp
http://www.speedtalk.com/forum/viewt...01f9ee77937530

CB horizontal discharge tube is not annular.

The term "annular" refers to a ring of holes whether it be like the 650 Holley 2 Barrel that had no booster at all, or an annular booster as fitted to some Holleys, 750 DP 9379 and models 4010,4011 are examples.

Annular could be done, but it would mean a custom "tall" venturi since the annular ring needs to be inline with the main well discharge port in the carb body.

[hyper4mance2k]

I'm really interested in doing horizontal or annular discharge tubes for the 48IDA. I think they'd be a great tool for tuners out there.

[Caprimaniac]

Originally Posted by Eljaro

Repairing the pump jets seat did help in preventing them from dripping while the engine runs. The vacuum inside the Webers was drawing fuel out of some of them. That does not happen now.

Eljaro. You were troubled with too fat condition in the lower end.
Did the repair of the pump jets make you come closer to a solution of the problem?

I run F11 tubes. 165 main and 210 air, very, very fat around 3-4000. Changed to 140/200 and it's a little better. (May be too lean higher on the scale; have not run an A/F- meter yet.)

I consider changing to F15 emulsion tubes.

And what you not see as an option, and I agree some, but still tempted to try: .035 exhaust.

Guess I don't need to ask; you'd tell me to try the F15?

[Eljaro]

Caprimaniac
My situation at this time is:
choke 42
etube F11
main jet 155 (140 is too small)
air corrector 120 (200 will lean you out at high rpm)
idle jet 70
idle holder 100
pump bypass 0.50

I have quite a good setting now, with the plugs having a nice tan color. The repaired pump jets did prevent fuel from being drawn down the throats on idle
I was running a 0.00 bypass with some black smoke out the exhaust and I did also see sometimes fuel dripping out the pump jets. Now with the 0.50 I have a slight bog when flooring suddenly.
I think that has to be an ignition timing problem now.

I was having problems with irregular running engine at around 4000 rpm. I did close the hood scoop to air flowing in and things got better. The engine does not hesitate now at cruising speeds and all the plugs have the same color. Before the # 1 and 5 plugs read rich and the others lean. The engine temperature is more stable now too and stays at 80ºC going fast or slow
But the timing is still erratic at around 4000 rpm. I think the distributor need some work done to it.
With the black stop bushing (theoretical stop limit 18º) in the MSD distributor and setting for a maximum of 36º advance the idle comes down to only 12-13º.
The initial advance should be 20º or higher to give a crisp response but then the max advance goes above 40º which is no good. I will have to check the condition of the stop bushing or make myself a custom on to achieve 20-22º initial advance and and 36º maximum. I will have to go to the stronger spring too, because I think there is some bouncing going on inside the distributor when the centrifugal weights hit the limiter bushing.
And max timing advance in by 2500 is not necessary if you are running 20-22º initial, but rather 3000-3500.

I thing this initial timing should get the bog out of acceleration with the 0.50 pump bypass in place.
I will check the bushing issue post results.

[Caprimaniac]

Thanks for update, Eljaro.

Am I reading you correct: F11 tubes + 0.50 bypass works for you? No F14 or soldered F11's, then.

I have never seen the acc. pump jets dripping under idle, cold or warm, so let's say I do not have any issues there.

I will need an A/F check to see if my current setup is too lean, but- as far as gutfeelings go- the engine might run not so well now as it did with the 165/210- combo.

As far as timing is concerned; I run 14 deg @1000 rpm, 38 @ well.. 3500? Never checked closely. It's a Mallory unilite. Let's see what your timing adjustments do! Will ait for your update!

RuneS

[Eljaro]

Trying to find the culprit of an annoying hesitation above 3500 rpm , which finally was solved by correctly phasing the MSD billet distributor, I had come astray of my "good" settings on the webers.
After testing all week long I have these settings now:
40mm choke
145 main jet
150 air corrector
F14 emulsion tube
0.35 pump bypass
65 idle jet
100 idle holder
idle screw 1 turn out
21º initial advance, max 36, with a self made stop bushing.
Heavy silver springs max advance at 3200 rpm.
Car idles at 600 rpm if needed but I have it at 800. Starts without pumping the gas pedal.

Cam is a hyd.roller with 242/248 duration in a 482cid KC Pond alloy SO.

The car ran fantastically good. I hit several times 140mph (5000 rpm in 5th) with no sweat. Very smooth and snappy all the time.
Maybe the 00 bypass will remove the very slight bog if I floor the pedal suddenly below 2000 rpm but from 2000 rpm in 4th I can floor it and it just goes.
Also the idle circuit is not 100% as it will slightly hesitate below 2000 on progressive acceleration. Maybe the 00 bypass will help here too.
Definitively the F14 tube is the best, and with it the 150 air corrector gave no leaning out at WOT.

So the main circuit is now set for me, only the idle will need some working on.
I will try the 00 bypass, and it that does no do it I will try an 80 idle holder.

BTW today I used my new Avon CR66ZZ for the first time. Wow, does it improve roadholding and breaking. My old Yokohama Avid were 5 years old and rubber was probably dry, but the car never handled as good as today.
Very recomendable.

[Hans-Olof Blom]

Eljaro,

I also have a 482 engine but with a little more cam. I am running a Holley 850 DP at the moment.

I have a Weber set-up with at present 42 mm chokes. Maybe I will swith to the Webers this winter.

Is the jetting with 40 mm chokes better than the jetting with 42 mm chokes you presented earlier in this thread?

[Eljaro]

Hans,
I have not tried the 42 chokes jet. Had to sort out several variables first in order to get the 40mm chokes to work right.

[Hans-Olof Blom]

Originally Posted by Eljaro

Caprimaniac
My situation at this time is:
choke 42
etube F11
main jet 155 (140 is too small)
air corrector 120 (200 will lean you out at high rpm)
idle jet 70
idle holder 100
pump bypass 0.50

I have quite a good setting now, with the plugs having a nice tan color. The repaired pump jets did prevent fuel from being drawn down the throats on idle
I was running a 0.00 bypass with some black smoke out the exhaust and I did also see sometimes fuel dripping out the pump jets. Now with the 0.50 I have a slight bog when flooring suddenly.
I think that has to be an ignition timing problem now.

I was having problems with irregular running engine at around 4000 rpm. I did close the hood scoop to air flowing in and things got better. The engine does not hesitate now at cruising speeds and all the plugs have the same color. Before the # 1 and 5 plugs read rich and the others lean. The engine temperature is more stable now too and stays at 80ºC going fast or slow
But the timing is still erratic at around 4000 rpm. I think the distributor need some work done to it.
With the black stop bushing (theoretical stop limit 18º) in the MSD distributor and setting for a maximum of 36º advance the idle comes down to only 12-13º.
The initial advance should be 20º or higher to give a crisp response but then the max advance goes above 40º which is no good. I will have to check the condition of the stop bushing or make myself a custom on to achieve 20-22º initial advance and and 36º maximum. I will have to go to the stronger spring too, because I think there is some bouncing going on inside the distributor when the centrifugal weights hit the limiter bushing.
And max timing advance in by 2500 is not necessary if you are running 20-22º initial, but rather 3000-3500.

I thing this initial timing should get the bog out of acceleration with the 0.50 pump bypass in place.
I will check the bushing issue post results.

So the 42 mm chokes above should be 40 mm?

[Eljaro]

That was a mistake, it was the 40mm ones.

[Caprimaniac]

Now I'd need some advice: If the low rpm's were to be leaned out, and you still need enough fuel at 8000 rpm and when stepping on the throttle, would the F14 or F15 be the "best" one? Both have high holes only, as I understand, but the F14 has 8,2mm and F15 8 mm outer diameter.

If the walls of the tubes are exactly same thickness, then the F14 should have a larger fuel reservoir by larger inner diameter.

The theory of capillary forces acting inside the tubes have made me wonder after reading some: Passini say the larger inner diameter makes fuel move higher inside the tubes (if I remember correctly). My own experience is that the fluid will climb higher in a smaller diameter tube. Any thoughts on this?

RuneS

[Eljaro]

I have been fine tuning my webers, especially trying to lean out the whole thing, because it was smelling too much of gas and using a lot of it..
Large main jets and idel jets are fine and make things run, because they mask any other deficiencies in the choice of air jets.
I went to smaller jets , 55 idle and 145 main and worked myself up from there.
At idle the A/F ratio came down to 13.5 on idle, but went very lean when starting to move.
So I removed the 120 idle air jet and went to a 100, which improved things a lot. I subsequently installed a self made 80 ( drilled out a 60 idle holder) idle holder air and things got in line quite well.
I noticed a slight lean hole when accelerating, so decided to open the pump Jets up from 50 to 60.Good result.
The main jets at 145 were a little too rich and power and acceleration was slightly hampered, at 13.5 to 14 A/F ratio. Since I wanted to achieve a A/F ratio of 12.8, which is for maximum power I installed a 155 main jet. The air jet is 120 and maintains the 12.8 ratio up to max rev , that is 6200 rpm.
The whole thing is slightly on the rich side, but I just thing that it has to be like that to make these engines run to its best.
Definitely Webers give these engines the crisp and inmediate response other carburetors don’t. I always had problems with Holleys sputtering when taking fast corners or when breaking hard (killing the engine in the process). Whit the Webers this is now an absolute race engine, with incredible torque and reving capabilities ( I have an aluminum flywheel) and a sound to make you absolutely happy.
I have a friend who is a Rally champion here in the Balearics( with Ford Cosworths and the like), and who had a chance to drive in McLaren F1 and several top Ferrari models. He said that the sensation of brute power and of blood draining acceleration he had in my Cobra topped anything he had driven before.
If you snap the gas pedal open from 1500-2000 rpm , first you go sideways, the back trying to overtake the front by the right side. You correct for that and there you go off like a rocket.
Fantastic sensation. You better have some good driving experience doing that or you can destroy yourself.
Anyway, my concept of supercars has changed a lot. For sheer fun I only need my Weber equipped Cobra, nothing else.

[Eljaro]

I have been fine tuning my webers, especially trying to lean out the whole thing, because it was smelling too much of gas and using a lot of it..
Large main jets and idel jets are fine and make things run, because they mask any other deficiencies in the choice of air jets.
I went to smaller jets , 55 idle and 145 main and worked myself up from there.
At idle the A/F ratio came down to 13.5 on idle, but went very lean when starting to move.
So I removed the 120 idle air jet and went to a 100, which improved things a lot. I subsequently installed a self made 80 ( drilled out a 60 idle holder) idle holder air and things got in line quite well.
I noticed a slight lean hole when accelerating, so decided to open the pump Jets up from 50 to 60.Good result.
The main jets at 145 were a little too rich and power and acceleration was slightly hampered, at 13.5 to 14 A/F ratio. Since I wanted to achieve a A/F ratio of 12.8, which is for maximum power I installed a 155 main jet. The air jet is 120 and maintains the 12.8 ratio up to max rev , that is 6200 rpm.
The whole thing is slightly on the rich side, but I just thing that it has to be like that to make these engines run to its best.
Definitely Webers give these engines the crisp and inmediate response other carburetors don’t. I always had problems with Holleys sputtering when taking fast corners or when breaking hard (killing the engine in the process). Whit the Webers this is now an absolute race engine, with incredible torque and reving capabilities ( I have an aluminum flywheel) and a sound to make you absolutely happy.

I have a friend who is a Rally champion here in the Balearics( with Ford Cosworths and the like), and who had a chance to drive in McLaren F1 and several top Ferrari models. He said that the sensation of brute power and of blood draining acceleration he had in my Cobra topped anything he had driven before.

If you snap the gas pedal open from 1500-2000 rpm , first you go sideways, the back trying to overtake the front by the right side. You correct for that and there you go off like a rocket.
Fantastic sensation. You better have some good driving experience doing that or you can destroy yourself.

Anyway, my concept of supercars has changed a lot. For sheer fun I only need my Weber equipped Cobra, nothing else.

[What'saCobra?]

My commendation on your patience and success. It is true that when set up correct, NOTHING is better "feeling" than the Webers compared to any Holly (though i have absolutely NO experience with their fuel injection units.)

When i moved from Weber-equipped Cobras to Weber-equipped FA/5000 (all Chevys), the crispness of a proper set-up was similar. However, it must be said that a poor Weber tune is also one of the most awful experiences, nearly always rich or very lean in a few spots (ergo the common spitting back through the intake, while stinking of excess fuel). You have to admire the Italian style and patience with making Ferraris run correctly and with fairly reasonable fuel economy. Though, mind you, their engines are generally very small displacement per cylinder and the smaller venturi systems seemed to be better metering in the day then our carbs(that is, maintaining correct fuel/air ratios with better precision when warm. Even the street cars, however, were cold-blooded beasties, needing warm manifolds and warm gear-boxes to run correctly. But, when warm, they were simply fine to drive and hear.

The only better system i have ever driven has been the Lucas/Kinsler mechanical injector systems that were common on the large Can-Am cars. Jim Kinsler, Bless his soul, knows how to design, assemble and tune those systems to a fare-thee-well, just about perfect.

The Lucas system uses a shuttle-cock moving back and forth over a changing-length tube to vary the amount of each fuel charge rather precisely. Injecting the fuel from the top of the big intake tubes (often referred to as Calliope tubes) allows the air-fuel mixture to be quite homogenized by the time it gets to the intake port. Once the manifold is warm very little fuel "wetting" occurs, with little corner edges to pass via a long straight shot. With such large openings and long lengths very little drag exists, while plenty of mass-momentum is available.

The Lucas absolute free-flow rate available is far over 4000 cfm, but of course is far in excess of even the biggest road-race Chevy. But, with the precision charge of the mechanical shuttle-cock, completely the opposite of the older constant-dribble Hilborn systems, the engine tolerates wide-open-throttle demands even at medium rpms with ease.

The net result is a wonderful flat torque curve AND a very high peak power, all the way from 2500 to over 7500 rpms. For road racing, this is ideal. If you miss a shift and skip a notch on the way up (not an unknown error?), the engine will still pull like a freight train and very little time will be lost.

The only drawback is the very tall pipe configuration, not welcome under any hood, but ideal for mid-engine layouts. You have to admit, having those huge pipes sticking up in the back is very appealing eye-candy, no? (See red car picture in file)

Oh yes, another drawback is a current new system is around 20K USD. Plus, depending.

Again, my compliments for your set-up.

PS: Lately, i have been thinking that one of the newest Holly Dominator systems with a tall hand-fabricated intake manifold, might be able to replace the old Lucas, but would have to test it properly, far beyond my current retirement planning. Lots cheaper, though and far better metering (accuracy in F/A ratio) than in the past. Holly has done a lot on this and i would love to try one.

[dallas_]

Good update. Sounds like you got it dialed in pretty good!

Can you elaborate on your setup to read your A/F ratio's?

[Eljaro]

I have a wideband Lambda sensor with a bung installed in the left exhaust pipe, where the four headers meet the exhaust. An Innovative LM-2 A/F ratio meter gives me the readings. I read the A/F ratios while driving the car.

[Eljaro]

As you probably know from my other thread my Weber experiments have come to a sudden halt.
The crankshaft could not bear the enormous torsion forces of the snap action acceleration combined with a light flywheel. It broke in half and exploded part of the block.
Yes, the eagle crankshaft has broken just before the second bearing cap at the front and has taken the Pond aluminum block with it, so the engine is now for a general rebuild, well , rather a general replacement.
Will probably go with a new but cast iron block and will try to get a better crankshaft, forged or billet. The steel eagle crankshafts seem to break elswhere also, I have seen other broken ones in the web.
So I am very sad, but one thing can positively be said about the Webers. They made my engine behave at its best. My last settings were probably the best ones I managed to achieve. Can't wait to have the engine back together and enjoy the brutal response the Webers transmit.

[Rick Parker]

Eljaro: I totally agree

They made my engine behave at its best.

From my perspective the transformation when the Webers were added were far above my expectation. The increase in the torque is what impressed me the most. I'd love to be able to have 13:1 compression too!!!!.

[Caprimaniac]

Sorry to hear that, Eljaro.

But it sounds as you are still happy about finding that Weber jetting suiting the engine well!

I had to get a new rod and the crank reground this fall, just to show that you're not alone in the rebuilding league.

Did you use a Eagle forged 4340 crank, or the cast type (hopefully cast, or else there will be very little good to say about those eagle forged cranks... and I use one myself!)

I cannot say anything about Webers VS other induction setups because I've had Webers since the first day I ran a V8!

G'night
RS