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Single sidedraft info only


Crashtd420

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Yeah, I'm pretty sure that the Holley regulator is good for 99.99% of the guys here on Ratsun. Surging fuel pressures can affect tuning, but will an engine making 50%-60% of its power potential even notice? Doubtful.

 

Besides, what is the range of the surge? It's still within the acceptable range of a DCOE, DGV or PHH carb.

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  • 4 weeks later...

Should I be deleting the stock fuel rail that has the return? I seem to start running a lot better waaaaaaay after the engine has been warmed up. I'm thinking that the fuel might be trying to go back through the return line, which is all hooked up. I get weird random bursts of full lean up until about 15 minutes of driving. I feel like it ran better on those super hot days we had a while back. Not sure. It drives perfect on anything under 1/4 throttle during that time

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And willz... I bought the same wideband o2 kit and couldn't be happier. Just got mine installed,... such a good unit... and it will do data logging with a simple computer hook up.... but I was surprised it didn't read a tach signal... maybe that's where the add on modules come in...

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  • 1 month later...

I had a 750cfm Holley on a car-tec water cooled intake. I changed it out for a 600 street performer detuned to a 400 race jet. It ran amazing, it was called a Paul Newman setup, it was a Turbo car raced in FL . It was setup like his 24 hrs of lemans winning 71 240z.

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  • 6 years later...
Found this info.


Conversion equipment jet setting Datsun B110 (A12) - single 40 DCOE 2
Choke size 27
Aux. venturi 4-5
Main jet 1-10
Emulsion tube F7
Air corrector jet 1-65
Idle jet 0-50 F9
Accel. pump jet 0-50
Accel. pump inlet valve with ex. orifice 0-50
Needle valve 2-00


Datsun B210 & F10 (A14) - single 40 DCOE 2
Choke size 33
Aux. venturi 4-5
Main jet 1-30
Emulsion tube F11
Air corrector jet 1-80
Idle jet 0-50 F8
Accel. pump jet 0-60
Accel. pump inlet valve with ex. orifice closed
Needle valve 2-00


Datsun 510 (L16) - single 45 DCOE 13
Choke size 33
Aux. venturi 4-5
Main jet 1-30
Emulsion tube F16
Air corrector jet 1-90
Idle jet 0-50 F8
Accel. pump jet 0-50
Accel. pump inlet valve with ex. orifice 0-55
Needle valve 2-25


Datsun 510 (L16) - dual 45 DCOE 12
Choke size 32
Aux. venturi 4-5
Main jet 1-35
Emulsion tube F15
Air corrector jet 1-70
Idle jet 0-55 F2
Accel. pump jet 0-40
Accel. pump inlet valve with ex. orifice 0-55
Needle valve 2-00u


40 DCOE-151 redline #19550.174 baseline jetting
32 Venturis
4.5 Aux venturis
115 Main jets
F11 emulsion tubes
200 Air correction jets
45F9 Idle tubes
40 Pump jet
50 Pump exh
1.75 Needle valve
huicho: SINGLE 40 DCOE ON A STOCK A15 ROUND PORT
COMPLETELY STOCK A15 economy version(round port head)
Main Venturi 32
Aux. Venturi 4-5
Main Jet 140
Emulsion Tube F-11
Air Corrector Jet 200
Accel. Pump Jet 60
Accel.Pump Inlet Valve with Ex. Orifice closed
Needle Valve 200
Idle Jet 55F9.
If you do not use an air filter:
* 180 on the air correctors
* 130 on the main jets Edited by Doctoraudio
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Process
Start with venturi/choke size. For dual-carbs (one barrel per engine cylinder) 28mm is good for max power with good flexibility at 6000 RPM with a 1.2-liter engine. Larger venturis will make good power, but with less flexibility (flat spots, poor part-throttle response). See Carburetor Sizing.

Next, set the float. Everything is affected by the float level, so do this first.

Float Settings
Early brass float: 8 to 8.5mm
Late plastic float: 12.5 to 13mm
In DCOE series, the main jet should start at 4 x venturi size. For example, with 30mm venturis start with 120 Main Jets.

The Air Correction Jet should be 1.25 to 1.50 of the Main Jets (some say main jet + 50). For 120 main jet, start with 165 Air Jets.

That much is easy (setting the air/fuel ratio which is around 13:1 for all engines). The trickier part, for which tuning to the particular engine is called for, is the transitions:

When accelerating the pump jet and duration are the main factors
Transition between idle circuit and cruise circuit is controlled by the Emulsion Tubes and Idle Jets. Do not attempt to fudge this by raising or lowering the float level. The Float Level should be set to the Weber specifications before any other tuning is done.
Warm the engine up fully and set the Idle Speed. For a stock factory spec engine, set the idle speed to 800 RPM. The speed screw should be 1/4 to 1/2 turn in after contact with lever maximum. If it won't idle down to 800 RPM something is wrong - most likely the throttle shaft nut has been overtightened binding the throttle. But it could also be the linkage is jamming (inspect carefully). An air leak can also cause a high idle (either loose carburetor parts, a bad gasket, or a leaking/cracked hose).

dcoe_a1.jpg

After setting the idle speed, adjust the idle mixture screw to Lean Best Idle.

If setting Lean Best Idle requires the mixture screw to be turned out 1-1/2 turns or more, the idle jet is too lean. Replace Idle Jets with half-size larger.
If the mixture screw is 1/2 turn out (or less) from seated the Idle Jets are too rich. Replace Idle Jets with half-size smaller.
If the Speed Screw is out more than 1/2 turn, the idle system is lean. This will cause problems with tuning the carb, so fix it now by fitting larger Idle Jets.
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40 minutes ago, Doctoraudio said:

Is there any other info?

I am running a LZ 2.2
With a 45mm single side-draft carb.
Not installed yet.
But in the next couple of days!

I think you got a good starting point...

Only other 2 things I can think of are 

1) you should also make sure the air flow between the 2 barrels are balanced...

2) if it's in the budget an air fuel gauge can be very helpful....

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