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azzurro

azzurro's 125p Pickup dyskusja

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Pretty sure I flipped one throttle shaft so the two short ends where facing each other to make mine fit and had to custom fabricate the linkage.

But what I really don't understand, how can you balance the carbs and not test drive?

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On 06/04/2019 at 21:28, NickJ said:

Pretty sure I flipped one throttle shaft so the two short ends where facing each other to make mine fit and had to custom fabricate the linkage.

these ones had equal length shafts so i left them where they were and trimmed them

On 06/04/2019 at 21:28, NickJ said:

But what I really don't understand, how can you balance the carbs and not test drive?

Good Question!

Mainly cause I used up my car time and had to do something else.

Next day i did go for a hoon, went ok (better than the single carb!), but rich and lean spots and hanging on idle, etc, carbs not going back to idle in balance, etc

So,

  • I pulled off the carbs
  • tweaked/ground back the linkage a bit more (master and slave levers were interfering with each other a bit),
  • drilled the carbs mounting holes to 9mm (from 8.5) for that little extra bit of slack,
  • reset the float levels, (12mm for these newer ones with a 26mm droop  vs 8.5 and 15mm for the older style) 
  • pulled all the jets and gave them a clean out - two main jet stacks were not fully seated, and one accelerator pump jet was blocked
  • ground some of the dizzy scoop on the manifold some more (while i could feel how thick the wall was with the carbs off) 
  • installed carbs and rebalanced/set idles etc
  • hooned

Great success, but does have a lean point off idle (progression holes?)  and is a bit rich elsewhere esp on WoT, thinking of upping the mains to the 135 i have (up from 125) but also increasing the air corrector to reduce the richness at higher rpm (190 currently, no spares), but that is for later.

Engine runs and pulls much better than with the single already, sounds great on song and has a pleasing burble at idle, and near silent on cruise with an instant response to stabs of the jandle.

reccomended :)

 

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For Future reference:

Weber 40 DCOE 151 on Fiat 1585cc twin cam:

Main Jet 125

Main ET F9

Main Air 190

Idle Jet 45 F9

Accell Pump Jet 45

Chokes 32

Venturi 4.5

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How many turns off the seat are the idle screws? off idle sounds to me like the idle jet needs to come up a fraction. screw depth off the seat is a good indicator of where in the range the idle wants to be.

Also not returning to idle is a potential sign of a vac leak, is it possible that might be messing with you?

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4 hours ago, NickJ said:

How many turns off the seat are the idle screws? off idle sounds to me like the idle jet needs to come up a fraction. screw depth off the seat is a good indicator of where in the range the idle wants to be.

I will count them soon, they are all in the 1.5 to 3 turn range, idle AFRs are in the 12-13 range with small adjustments either way was making a big difference. I will richen it up a bit 

4 hours ago, NickJ said:

Also not returning to idle is a potential sign of a vac leak

no longer an issue after remove, trim and refit

4 hours ago, NickJ said:

is it possible that might be messing with you?

'is it possible it might be messing with me' he asks! "possible"? POSSIBLE!!!!111!!1

(shakes head walking away, throws arms up dramatically)

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I had the classic lean hole just off idle when I first put my old ones on, wideband would jump to 22:1 for a split second :shock:

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Mine dont quite go that lean (22 = no gas?) , but there is a definite stumble and AFR peak on some low throttle transitions

How did you solve it?

Reading my new books suggest a range of potential causes/solutions:

- idle jets to small, (45 fitted - i recon they will be slightly on the side of too big if anything)

- idle mix too lean (AFRs say 12ish at idle, yet to plug chop to see what they say, and all the books say 'give the engine what it wants' to idle best )

- throttle plate position relative to 1st progression hole at idle incorrect 

 

The last two only require a screwdriver and time, the first one requires $ and new jets, and i dont think 45s are too small on a very mild 1600.

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@azzurro Are they Weber 152 made in Spain versions?

if they are it’ll be the progression holes causing the issue. Or lack of, there should be 4 or 5 holes but the 152’s only have 3. The 4th hole should be directly over the butterfly.

Have a look how many holes it has, they are under the bigger brass flat head cap screw on the engine side. One for each throttle body.

Edit, like this:

2B2BE5DB-A0B4-4EE2-B0F8-509803E19A8E.jpeg

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V close, spanish 151 with a '92 casting date and 3 progression holes :)

I set the butterflies on the bench to there and also with a torch on the car a couple times to balance visually but not looked lately now they are balanced

Pretty sure low float levels/ excessive angle was/will be messing with my tune, beyond any design flaw, as while theres still a small stutter its nowhere as bad now i gave the inside/lower float a wee tweak

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Sweet as. That stumble at low throttle is caused by the butterfly opening, taking in air and not yet getting fuel from the progression holes.

Needs that 4th hole drilled directly over the butterfly to fix. It’s like a 1mm hole drilled in exactly the right spot.

My 130tc has this exact issue and I’ve been meaning to get it drilled for ages.

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Had a bunch of Lada stuff sent down and amongst was a Fiat starter motor, little use to me (except I might steal the solenoid) effectively mirror of the Niva unit, any interest to ya?

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14 hours ago, NickJ said:

Had a bunch of Lada stuff sent down and amongst was a Fiat starter motor, little use to me (except I might steal the solenoid) effectively mirror of the Niva unit, any interest to ya?

Well yeah, but nah, i picked up a nice low mileage/later model one in a random parts collection last week and have a few in storage in Auckland still. 

Cheers tho.

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