Idle question

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May 4, 2004 | 12:11 AM

fmc400

Thread Starter

MSEE

Joined: Apr 2004

Posts: 10,386

Likes: 35

From: Austin, TX

Idle question

Hi all,

I've been trying to get my idle speed and mixture right lately, and today as I was letting the engine idle I glanced down the carb, and noticed that fuel was dripping off the booster venturis. I don't think that's supposed to happen at idle, but correct me if I'm wrong. Could my idle be too high?

Thanks

May 4, 2004 | 09:40 AM

beartracks

Lead Driver

Joined: Nov 2000

Posts: 6,635

Likes: 349

From: Albuquerque

Not supposed to happen. At idle the only fuel supplied should be from below the butter flys. Your float level is probably set too high or the inlet valve clogged. Is the choke all the way off?

May 4, 2004 | 11:20 AM

fmc400

Thread Starter

MSEE

Joined: Apr 2004

Posts: 10,386

Likes: 35

From: Austin, TX

Yeah, at this point the choke is all the way open. I rebuilt the carb a couple weeks ago, got everything cleaned and believe the float height to be dead on. For good measure, I opened up the air horn and removed the booster venturis and blew out the idle air bleeds, no change. I lowered the idle and they stopped dripping, but that idle was too low to keep.

May 4, 2004 | 12:33 PM

fmc400

Thread Starter

MSEE

Joined: Apr 2004

Posts: 10,386

Likes: 35

From: Austin, TX

I would also like to point out that when the engine has sat overnight and I start it up the next morning, there's a light backfire out the carb.

Thanks

May 4, 2004 | 05:40 PM

fmc400

Thread Starter

MSEE

Joined: Apr 2004

Posts: 10,386

Likes: 35

From: Austin, TX

One more update. Today I checked the float height and did a wet adjustment. The fuel level was a bit high but I got it back down to normal. However, the venturi's still drip some. Any suggestions?

Thanks

May 4, 2004 | 06:17 PM

grclark351

Posting Guru

Joined: Dec 2002

Posts: 2,003

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From: chicago burbs

what is the idle rpm? if it is too high, the boosters will start to deliver fuel. just as you suspected in your first post.

May 5, 2004 | 08:39 AM

ashvalentine

Senior User

Joined: Jan 2003

Posts: 176

Likes: 0

From: Addison,Texas

How far open are the throttle plates at idle? They're supposed to be almost closed.

ash
['Did you get the check ball and spring and stuff back in right?']