DCOE 40 "burn your eyes rich"

[chaseincats]

Question for you guys - I have a friend who bought this: https://www.ebay.com/itm/Weber-DCOE-Kit-fits-Datsun-240Z-260Z-280Z-Triple-Performance-40-DCOE-K659/272778769560?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649&fbclid=IwAR1-Pa61k0L6wA2H0mXxTlwqbQ5MLFtBQT5KGbX4TlrUgjEMWnvBwIyfpWE

Even with the air mixture screw set to max-lean, the exhaust out of this car is so rich it burns your eyes within a few seconds.

Are the jets this kit comes with too aggressive?

 

-chase

[jitenshakun]

Can you post up the jets? Its as easy as popping the inspection cover and using a flathead to back out the jets.

Idle jet, main, and emulsion tube at the minimum please.

[chaseincats]

Ok - let me msg my pal 

[jitenshakun]

Is your friend running a mech or electric fuel pump? Either way, a pressure regulator may be needed as Webers only need 3psi or so of fuel pressure.

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[chaseincats]

16 hours ago, jitenshakun said:

Is your friend running a mech or electric fuel pump? Either way, a pressure regulator may be needed as Webers only need 3psi or so of fuel pressure.

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Since it's a 260 it has both - a mechanical pump in the front and an electric in the back.  It has an in-line pressure regulator on there set to 2.  I believe this is the regulator he has: https://www.oreillyauto.com/detail/b/mr--gasket-4367/performance-16477/engine-16841/fuel-system-16571/fuel-pressure-regulators-17798/37354b4805ef/mr-gasket-fuel-pressure-regulator/9710/4514726/1978/nissan/280z?pos=1

 

EDIT: He only has an electric fuel pump in the back set to 2.5 psi

Edited October 17, 2020 by chaseincats

[jitenshakun]

At 2 psi he isn't flooding the bowls. I'm surprised it runs rich with the idle screwed in all the way. That practically shuts the fuel off. Screwed in for lean, out for rich...

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[chaseincats]

2 minutes ago, jitenshakun said:

At 2 psi he isn't flooding the bowls. I'm surprised it runs rich with the idle screwed in all the way. That practically shuts the fuel off. Screwed in for lean, out for rich...

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Yeah, that's what's so strange about it and leads me to believe maybe the jets that kit comes with are too large?

[240260280]

Check fuel levels.

- Remove one main jet assembly in each carb.

- Measure distance from top of fuel to the bridge where the main jet screws in.

 

At 23mm, the fuel will pour into the carb throat.... not good.

At 25mm down, the fuel will slosh into carb throat on bumps and such

29mm down is recommended.

31 to 27mm is a range for tuning.

 

 

[chaseincats]

1 minute ago, 240260280 said:

Check fuel levels.

- Remove one main jet assembly in each carb.

- Measure distance from top of fuel to the bridge where the main jet screws in.

 

At 23mm, the fuel will pour into the carb throat.... not good.

At 25mm down, the fuel will slosh into carb throat on bumps and such

29mm down is recommended.

31 to 27mm is a range for tuning.

 

 

Thanks, I'll pass the message along.

[240260280]

For stock 240z to 260z, here are approximate fueling need sizes:

 

Idle Jets are typically 45 to 55 (fuel hole in bottom is 0.45 to 0.55mm)

Main Jets are typically 115 to 125 (fuel hole in bottom is 1.15 to 1.25mm)

[chaseincats]

1 minute ago, 240260280 said:

For stock 240z to 260z, here are approximate fueling need sizes:

 

Idle Jets are typically 45 to 55 (fuel hole in bottom is 0.45 to 0.55mm)

Main Jets are typically 115 to 125 (fuel hole in bottom is 1.15 to 1.25mm)

Will he have to measure the opening hole, or will the size be stamped on the jet?

[jitenshakun]

Stamped on the jet.

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