Tuning 40 DCOE Weber 151 on an L24

[jitenshakun]

Tip in means when I accelerate.

I'm using an innovates AF in the header and a mech gauge to read.

I have 130 and 120 jets on the way given my 10:1 at WOT.

[jonbill]

so when you accelerate from cruising at 13.5:1?
what size chokes are they?

[jitenshakun]

Chokes are an unknown, so I assume the stock given 42 chokes are like unicorns.

When I accelerate from cruising it goes

13.5:1 cruise -> 18:1 for a bit -> 10:1 on mains.

[jonbill]

take a choke out, it'll either be marked or you measure it.

assuming you're opening the throttle reasonably slowly, your 18:1 is on the progression holes or between the progression holes and the main jets.
progression holes are supplied by the idle jets.

[jitenshakun]

Opening slowly or mashing it results in the same spike in AFR and engine shudder. 

Because I can't actually change my chokes I haven't been bothered by what they are.  Are possible solutions different depending on the size of the chokes?  E.g. if a choke were smaller I'd look at my idle jet vs. looking at my main jet if I had larger choke?

Sorry if this is a dumb question, but I'm learning here.

[240260280]

Usually there is a lean blip then a rich drop. It is hard to tune out.

Make sure your fuel levels are all the same across the 3 carbs. 30 to 27mm down from the jet bridge works nicely.  Aim for all 3 to be a 29mm as a staring point.

 

 

Edited September 18, 2020 by 240260280

[jitenshakun]

I haven't checked bowl levels yet. Good tip. Thank you.

[jonbill]

 

 

 

 

Opening slowly or mashing it results in the same spike in AFR and engine shudder.  Because I can't actually change my chokes I haven't been bothered by what they are.  Are possible solutions different depending on the size of the chokes?  E.g. if a choke were smaller I'd look at my idle jet vs. looking at my main jet if I had larger choke?

Sorry if this is a dumb question, but I'm learning here.

 

 

yes. the choke size determines the air speed and suction at the main jet outlet, which determines when the main jet comes in (in part). so with a big choke, you can run out of progression holes before the main jet kicks in and it goes lean and the answer is to fit smaller chokes or possibly add progression holes or if its marginal you can get away with just larger idle jets and make the progression phase richer to cover the transition to main jets.

 

with small chokes, you're probably just lean through the progression phase and bigger idle jets/richer idle holder wil fix it (and you turn down the idle screw so its not too rich at idle).

 

why do you say your chokes can't be changed?

 

 

 

[jitenshakun]

Chokes for 42 DCOE are had to come by because the carb is non-standard.

The carbs have 2 progression holes.

[jonbill]

Ah right, the 42 DCOEs! I still think it would be helpful to have one out and measure it. Perhaps after you've checked the float levels.

Is there a gap between the two progression holes, or will the throttle plate start uncovering the 2nd as soon as it finishes the first?

Do you think you can position thr throttle pedal at the problem point while the car is stationary?

You could get someone to look at the progression holes for where the throttle plate is when the problem occurs. after the 1st hole or after the 2nd.

 

 

[jitenshakun]

I have someone that can help with watching the progression holes and butterfly. They are spaced, but not a lot.

I have new gaskets on the way so I can measure when I swap those in. I'd like to eliminate the chance of a vacuum leak.

[Zedyone_kenobi]

Long story which I will summarize later 

but does anybody have a Keith frank clear acrylic float adjuster rod with the markings on it. I have misplaced mine and my old eyes really needed that.