Good stuff Chuck! Try the fuel height at ~ 27-29mm and report back if you can.

Also let us know what the jets, tubes, chokes, and motor details are. Data is king.

Great thread here guys, thanks for the information.

I have a situation with mine that I'm hoping someone can shed some light on.

Dcoe 40's, stock cam l26 f55 idle jets, float level on all set correctly, synced perfectly, timing at 18degrees initial with a recurved dizzy.

Cruise afr is 12.5 to 13 but my idle needs to be very rich (9.5) or I get popping through the carbs when transitioning to cruise rpm.

Any ideas? Car runs great otherwise. Just a little baffled as to my my idle need to be so rich.

Thanks,

Dean

A few more questions...Need more data...

Which F55 jet are you running?

55f8

55F9

55F11

Also, what Etube are you running and what air corrector and main jet

What do you consider cruise RPM.

So when your idle is at 9.5:1 your cruise rpm is pretty good. You could actually afford to lean it out a bit more in the cruise afr.

More info would be nice though before just guessing.

A few more questions...Need more data...

Which F55 jet are you running?

55f8

55F9

55F11

Also, what Etube are you running and what air corrector and main jet

What do you consider cruise RPM.

So when your idle is at 9.5:1 your cruise rpm is pretty good. You could actually afford to lean it out a bit more in the cruise afr.

More info would be nice though before just guessing.

Idle55f9

170 air corrector

F11 emulsion

130 mains(way too rich,have ordered 120's

Cruise is around 2200 rpm

What is your fuel level set to.

What is your fuel level set to.

26mm from the base.

Just did some tuning with DR240z. We settled on this:

 

Engine:

Block: L24

Head: Maxima N47

Cam: ~280 duration 0.48" lift

 

Transmission and Differential: stock 4 speed 3.545

 

Carbs:

40DCOE151 (3)

30mm Choke

Fuel Height: ~30mm down from top of body

Idle Jet: 55F9

Enrichment Screws: 2.25 turns

Emulsion Tube: F11

Air: 70

Main: 120 

 

A/F Ratios:

Idle: 13.5

60mph cruise on flat: 15.6

70mph cruise on flat: 14.5

 

WOT runs 12-13

 

After setting fuel level to 30mm down, we first tuned by selecting a jet for cruise at 60mph that was near stoich (~15:1) and could be dialed to slightly rich for a smooth idle(~13:1).  The 55F11 did the trick.

 

We then checked the effect of the main on cruise. The car had a 115 main when the fuel level was 25mm down. We tried a 125mm main with the fuel now at 30mm down but it dropped the 70mph cruise to 12.5 w/o doing much to the 60mph cruise. We settled on the 120mm.

 

 

Tuning data:

 

 

The car runs crisp with no bogging nor rich fuel smell. 

 

Nice even mocha coloured plugs to boot.  No popping or backfiring under load, over run, or at any rpm.

 

Success.  

 

 

 

Edited August 10, 20159 yr by Blue

Just did some tuning with DR240z. We settled on this:

 

Engine:

Block: L24

Head: Maxima N47

Cam: ~280 duration 0.48" lift

 

Transmission and Differential: stock 4 speed 3.545

 

Carbs:

40DCOE151 (3)

30mm Choke

Fuel Height: ~30mm down from top of body

Idle Jet: 55F9

Enrichment Screws: 2.25 turns

Emulsion Tube: F11

Air: 70

Main: 120 

 

A/F Ratios:

Idle: 13.5

60mph cruise on flat: 15.6

70mph cruise on flat: 14.5

 

WOT runs 12-13

 

After setting fuel level to 30mm down, we first tuned by selecting a jet for cruise at 60mph that was near stoich (~15:1) and could be dialed to slightly rich for a smooth idle(~13:1).  The 55F11 did the trick.

 

We then checked the effect of the main on cruise. The car had a 115 main when the fuel level was 25mm down. We tried a 125mm main with the fuel now at 30mm down but it dropped the 70mph cruise to 12.5 w/o doing much to the 60mph cruise. We settled on the 120mm.

 

 

The car runs crisp with no bogging nor rich fuel smell. 

 

Nice even mocha coloured plugs to boot.  No popping or backfiring under load, over run, or at any rpm.

 

Success.  

 

 

 

Not too sure if this is important to note: Set up was carried out at 1250 feet above sea level and temp was 70 F

Reviving this thread as I'm a few years behind y'all...

L28/e88 combo with bone stock, albeit fresh, internals.  

DCOE 42.

135 Main

165 Air

55F2 idle

F15 emulsion

45 Accelerator

? Choke (haven't measured them)

50mm slide in velocity stacks

 

Car starts and idles great, but I'm pig rich at WOT (10:1), looking good at idle and cruising idle (13.5:1), and wildly lean at tip in (18:1).  

My guess is a previous owner went rich across the board to mask the lean tip in as much as possible.  I'm trying to get the AFRs better step by step and my question is whether success has been had to bigger acceleration jets?  

Leaning out my idle jet (F8 to F2) improved my driving idle, and accentuated my tip in lean spot.  

Waiting on jets to play some more...

135 main would be hinting at rich WOT.  Try a 125 as a first step.

Reviving this thread as I'm a few years behind y'all...
L28/e88 combo with bone stock, albeit fresh, internals.  
DCOE 42.
135 Main
165 Air
55F2 idle
F15 emulsion
45 Accelerator
? Choke (haven't measured them)
50mm slide in velocity stacks
 
Car starts and idles great, but I'm pig rich at WOT (10:1), looking good at idle and cruising idle (13.5:1), and wildly lean at tip in (18:1).  
My guess is a previous owner went rich across the board to mask the lean tip in as much as possible.  I'm trying to get the AFRs better step by step and my question is whether success has been had to bigger acceleration jets?  
Leaning out my idle jet (F8 to F2) improved my driving idle, and accentuated my tip in lean spot.  
Waiting on jets to play some more...

What setup are you using to measure A/f ratio?

Thx!


Sent from my iPhone using Tapatalk

what does 'tip in' mean?