Weber Intial setup - back to basics help

[SF_SN888KE]

been reading a lot of the weber tuning on this and other sites.

Have SBF 347, mild cam, 10:1 compression. New Jim Inglese system with turkey pan for Daytona replica.

If you are familiar with Inglese linkage, sync main carb (cyl 3-4) with carb on cyl 1-2, then sync carb on cyl 7-8, then carb on cyl 5-6. Could not get carb on cyl 5-6 to come up, so added idle screw and brought it up. essentially all carbs are very close. (cyl 5 is lower than cyl 6 - but that is another story).

Question for "best lean". It is my understanding that ALL of the mixture screws should be set the same. for example start ALL at 3/4 out from bottom and then listen for sound / rpm. Does this mean adjust "ALL" screws out/in the same? I tried this in the first go around and 2 plugs were nice and brown, 3 were white lean, 3 were black and my eyes were tearing! Gas mileage sucked. MPG dropped 3 from the Holley! Seems to me that each mixture screw should be set independently. Which is correct?

Then: if the 3 are lean white/ 3 black rich, I assume that you would change jets?

In a perfect world with a perfect engine / identical carbs - it makes sense to me that all mixture screws and jets would be the same. Should only the 4 middle carbs be synced and the 4 outter carbs go for the ride (or bend cyl 5 to match cyc 6?) Should ALL mixture screws be the same position from bottom? Should ALL jets be the same?

Want to get the carbs a little closer.

Thanks for the help ...

[zrayr]

have you called Jim with your concerns ? He will be able give a greater detailed response than you will get from the forum.

I wouldn't be concerned that your gas milage has dropped in comparison with the Holley carb. And 3 mpg is nothing to worry about. Actually I'm surprised it's not considerably less than that. You are getting a lot more air into the engine with the Weber set up, so it's normal for the gas consumption to increase.

Ditch the fouled plugs and start with all the mixture screws out 3/4 turn. turn each one in until the rpm begins to drop, then it back out slightly. None of them should out more than 1.125 turns, If they vary from each other slightly don't sweat it.

I'd do a plug check after a full throttle run before considering a jet change. And consult Jim before any jet changes. You paid a premium price for his system because that includes his technical assistance. Use it.

Z.

[cab]

search weber tuning part 1,2,3 on you tube this is how i do mine ,i start 1 turn out if I get a spit out the stack I open just a bit, if it pops a little on either side out of the pipes I will turn in just a bit on all carbs on that side then if any on that side spits I will open just the ones that spit,i got a jet ket from Jim after i got my webers and have made one change to a smaller idle jet from 65 to 60. I set my floats wit the tab ,I Set a caliper on the tab and measure down to the brass arm and it's .172 ,i also run the 3/16 phenolic spacers from jaycee's and 2.5 pressure. no more flooding .

[SF_SN888KE]

Long story over the winter: fuel pressure seemed to bounce so change the fuel pressure regulator to a low psi Holley and new low psi hi flow fuel pump. Defective FP so changed back to original Carter 7psi FP. (need to return defective FP and will change if fuel pressure keeps bouncing) Added new fuel filter before pump and another cheap clear plastic in-line before the webers ... busy at work, girlfriend and Rotary, Daytona came in 4th. Ran the rich webers for about 1000 miles last year. Now time to get more serious and get them tuned.

I did see the Weber 1-3 tuning on YouTube. Cool looking out fits. Have read a lot of the internet materials and have the Weber book and want to get a better understanding of the system.

Looks like I am on the right track. Called Jim a while back about the bottom manifold plate for vacuum, initial timing, etc. He did mention potential jetting changes. (BTW, beautiful turkey pan for the Daytona)

As I recall, all of the mixture screws are less than 1.125 turns out. Most are 1/2 to 7/8 turn out. Will double check my notes.

Not surprised that MPG would drop as the car screams when you punch it. But others have stated that MPG was actually better while cruising with a proper tuned set (low speed circuit) of Webers?

Any thoughts about adding an idle screw to carb 3 (cyl 5-6) to set the initial sync for all 4 IDA's? (in other words, using 2 idle screws instead of just one) Since all are connected through the bell crank, will they all accelerate the same or will 3 accelerate quicker than carb 3 (cyl 5-6)?

Also, I read something about initial tuning at 850-1000 rpm and then also checking the low speed circuit at 2000 rpm? If so, would you again turn in/out the mixture screw again for "best lean"?

Will ping Jim after I change plugs and make some runs and report new findings.

Thanks for any help.

[zrayr]

[quote=SF_SN888KE;1237842

"..............Any thoughts about adding an idle screw to carb 3 (cyl 5-6) to set the initial sync for all 4 IDA's? (in other words, using 2 idle screws instead of just one) ................."[/QUOTE]

the linkage already provides you with a separate idle adjustment for each carb. Otherwise you could never sync them.

Z.

[SF_SN888KE]

Z, I could sync carbs 1 (has the main idle screw - passenger side rear) and 2 (passenger side front), and 4 (driver side rear), but not carb 3 using the linkage. Carb 3 was low (or carb 4 VERY high) on manometer. Could not sync carb 3 and 4 using the linkage between them. I tried flipping the adjustments/linkage between carbs 3-4 but there was no space and I couldn't figure it out. If I set the cross linkage (adjusts the left /right bank) to carb 3 (e.g. 7 on manometer), then carb 4 was WAY too high (at 12 on manometer). The adjustment screw for carbs 3-4 seems to effect carb 4 - and I backed it all the way out and carb 4 would not drop and was still too high. Hence, set carb 4 to 7 on manometer and then raise carb 3 be adding the idle screw.

As I am writing this, maybe there is a way to flip the adjustment screw (carb 4 adjustment) with the spring stop (I think this is connected to carb 3? need to take another look)

As you mentioned, that is my concern - sync'd only at idle but what happens when you accelerate? Will carb 3 always lag behind? I guess I can try to raise the main idle screw to 1500 rpm, 2000 rpm and then check the sync?

Anyone else have this problem of sync'ing a high or low carb? How did they do it in the old days without the fancy linkage?

Will check the sync with higher rpm, and then with new plugs ... when I have more time.

[Gaz64]

Can you post some photos of your linkage?

[zrayr]

Originally Posted by SF_SN888KE

"............... As I am writing this, maybe there is a way to flip the adjustment screw (carb 4 adjustment) with the spring stop (I think this is connected to carb 3? need to take another look)

As you mentioned, that is my concern - sync'd only at idle but what happens when you accelerate? Will carb 3 always lag behind? I guess I can try to raise the main idle screw to 1500 rpm, 2000 rpm and then check the sync?

Anyone else have this problem of sync'ing a high or low carb? How did they do it in the old days without the fancy linkage?

Will check the sync with higher rpm, and then with new plugs ... when I have more time.

if you cannot balance a pair of carbs with the coupler screw (which is the ONLY connection between them) then there might be something bent in the mount for the coupler screw or the tab on the other carb where the coupler screw makes contact. All the coupler screw does is raise or lower the throttle plate for the #4 carb. It does not move in any way the throttle plate for #3. (You might have some other problem that is causing #4 not to close completely ?)

I would not for one minute consider a work-a-round for this issue. It needs to be solved. Also, if you did end up with one carb considerably more open than it's linked carb, then they would out of sync all the way up to wide open throttle. Not what you are wanting.

Sonds like you have the 3 / 4 carb pair with a too high of a pull from the rod connecting them to the 1 / 2 pair. If you back off that rod until the 3 / 4 carbs are completely closed, then open it just enough so 3 & 4 will barely run, then you should be able to sync 3 & 4 with each other first, then match that pair with the 1 /2 pair.

As pointed out, a photo of your linkage might help with the advice, but if you got your system from Jim Inglese I ave a pretty good idea what you have. It'd be nice to have the photo to confirm.

Z.

[SF_SN888KE]

SBF 347, mild cam ...

OK, I think I figured out the linkage where I can now get cyl 2-3-5-6 sync close. Not perfect, but at least the car is running and all throttles look to be operating in sync. Bell crank connects to Driver front carb (#4), which connects to Driver rear carb(#3), which connects via hex bar to Passenger Rear carb (#1), which connects to Passenger Front carb (#2)

New plugs, Autolite 24. Tried to hear "best lean", not easy on cobra/daytona's Used my timing light w/ tach on each cylinder to highest RPM. Ran car for 30 minutes, not too bad, no pops or major issues. Set the idle screw to 2000 RPM and tried the "best lean" using timing light w tach. Ran car back home and it started backfiring. Readjust again at 900 RPM using timing light/tach (over 1 hour of running time and 40 miles). Took car for drive on Sat, ran good after warm up, no pops, and seemed to respond well up to 6500rpm. Here are the plugs 1-4



#1 and #4 are dark and sooty. Should I lean out a bit (turn mixture screw in 1/8?)
#2 looks the best, but still a tiny bit lean. Leave alone?
#3 looks like white lean. Should I richen a bit (turn mixture screw out 1/8?)

use Autolite 24 vs ??? Tried Autolite Racing 13, Racing 25, and others.

Will pull drivers side plugs - got busy and a bit of a PIA.

Anyone ever hear or use the Colortune tool?

Thanks for your input

[zrayr]

Having all the mixture screws the same is a starting point, not a finishing point. However, you will find that a very small adjustment, like the width of a screwdriver blade, will have a substantial effect.

Z.

[Gaz64]

I have asked before, can you post a photo of your linkage system please?

Number 3 looks best to me, the shell colour is what your combustion chamber looks like and still a tad rich on average.

Could be borderline lean in some areas.

Number 2 shows lead fouling (yellow) on the porcelain.

The others are obviously too rich, or starving for air.