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Discussion Starter #1
i'm sorry i'm still confused after reading the sync threads. it seems everyone has some sort of home spun way of syncing carbs, but i can't get them close

i disconnected the throttle linkage

i turned out the idle speed screw so it didn't push down on the linkage at all, then gave it one turn

then held both carbs closed and set the sync screw till it just touches the center linkage

both barrels of the rear carb are sucking 11ish and both front are 3ish

should i mess with the idle mix screws? if both barrels are off the same would that mean i have something else out of whack? like the linkage is wrong still? of should i start turning the idle mix screws?

as always, thanks for all your help
 

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Richard Jemison
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7,394 Posts
Syncroniaing carbs

Simple and quick.......

Back off the idle stop screw (out of the way)
back out the syncro screw 1 full turn (or more if needed)

with a finger push closed the butterflies on rear carb. Holding it closed the spring in the linkage will fully close the front carb as well.

Screw in the balance screw until it "touches" the flat contact area of the balance assembly.

Turn the idle screw in to get proper idle.

Then you can set the idle mixture needles (screws) to get best idle.

No need to look at the plate position unless you want to and plan to repair a bent shaft. This gets it as good as it can be with carbs as-is........
 

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Trained (ex)Professional, , 1953-2018 RIP,
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16,232 Posts
No method will successfully sync the carbs correctly without the carb support rod and airbox installed. These components are required to ensure proper 'alignment' of the carbs.
 

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Discussion Starter #5
Simple and quick.......

Back off the idle stop screw (out of the way)
back out the syncro screw 1 full turn (or more if needed)

with a finger push closed the butterflies on rear carb. Holding it closed the spring in the linkage will fully close the front carb as well.

Screw in the balance screw until it "touches" the flat contact area of the balance assembly.

Turn the idle screw in to get proper idle.

Then you can set the idle mixture needles (screws) to get best idle.

No need to look at the plate position unless you want to and plan to repair a bent shaft. This gets it as good as it can be with carbs as-is........
great, i needed to rethink that. this got me set up!

And all four idle mixture screws are set the same? In other words, turned clockwise gently in to the stop then backed out 2 turns?
the mix screws shouldn't effect the "suck" of the carbs at idle thought, right? they really should just be the "richness" or "leanness" at idle.

to tell the truth i'm kind of liking 3 full turns. is two turns optimum?

the engine is finally accelerating like a real car now! thanks for all this help guys
 

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Richard Jemison
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7,394 Posts
Idle mixture screqs

to tell the truth i'm kind of liking 3 full turns. is two turns optimum?
The # of turns out is dependant on carb design, the angularity/taper of the screw and the size of the idle jet.

They should be adjusted to where each one is as lean as possible but providing good idle. Find the point that results in good idle after turning in too far and causing lean drop in idle on each cylinder. Then turn out gradually in 1/8 of a turn giving it a few seconds to acclimate to that fueling level. When you get to that point and it`s ideling normally turn it out another 1/8 turn. move to the next one and repeat until all 4 are done.

When that is complete if jetting in the carbs is "correct" it should pull smoothly from idle through the gears with no hesitation or balking.
If it is showing signs of "flat spots" the idle jets are too small or too lean a design.

If the flat spot can be eliminated by turning the 4 idle screws out by 1/2 turn you likely need the same design idle jet, but .05 larger. ( IE: 50 F-8 to 55 F-8)

If you are using a WBAfM to monitor fuel richness and you have idle OK and drivability OK but are showing richer than desired mixtures at nornal driving below 4000 RPM (We are not talking about acceleration!) then you can drill one 1mm (.040) hole opposite the existing 1.2mm air bleed hole) and effectively have an F7 idle jet which is about 3 steps leaner at higher demand than a F-8. This should resolve that issue.

PJ is correct you have to have a plate tying the carbs together, Tha Airbox served that function.
If you dont`t plan to have an airbox and run airhorns then you really need to rethink the use od airhorns! See:
http://www.alfabb.com/bb/forums/motorsports/146536-air-intake-webers-105-track-car.html
 

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Discussion Starter #7
And all four idle mixture screws are set the same? In other words, turned clockwise gently in to the stop then backed out 2 turns?
No method will successfully sync the carbs correctly without the carb support rod and airbox installed. These components are required to ensure proper 'alignment' of the carbs.
The # of turns out is dependant on carb design, the angularity/taper of the screw and the size of the idle jet.

They should be adjusted to where each one is as lean as possible but providing good idle. Find the point that results in good idle after turning in too far and causing lean drop in idle on each cylinder. Then turn out gradually in 1/8 of a turn giving it a few seconds to acclimate to that fueling level. When you get to that point and it`s ideling normally turn it out another 1/8 turn. move to the next one and repeat until all 4 are done.

When that is complete if jetting in the carbs is "correct" it should pull smoothly from idle through the gears with no hesitation or balking.
If it is showing signs of "flat spots" the idle jets are too small or too lean a design.

If the flat spot can be eliminated by turning the 4 idle screws out by 1/2 turn you likely need the same design idle jet, but .05 larger. ( IE: 50 F-8 to 55 F-8)

If you are using a WBAfM to monitor fuel richness and you have idle OK and drivability OK but are showing richer than desired mixtures at nornal driving below 4000 RPM (We are not talking about acceleration!) then you can drill one 1mm (.040) hole opposite the existing 1.2mm air bleed hole) and effectively have an F7 idle jet which is about 3 steps leaner at higher demand than a F-8. This should resolve that issue.

PJ is correct you have to have a plate tying the carbs together, Tha Airbox served that function.
If you dont`t plan to have an airbox and run airhorns then you really need to rethink the use od airhorns! See:
http://www.alfabb.com/bb/forums/motorsports/146536-air-intake-webers-105-track-car.html
thanks guys. i just could not get it right so i had to find someone to dial them in for me. but it is running pretty darn good. i really appreciate all the help and holding of my hand through all of this.

video:

now time to find a new owner.
 
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