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Author Topic: Rough idle  (Read 937 times)

Stan Paralikis

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Rough idle
« on: April 04, 2010, 04:41:36 AM »

Ok.  440-WOB II is running like a raped aped.  Pulls strong from idle to redline.  No stumble, bogging, or farting.  Mid range torque is super.  Right where I wanted it.  I'm super-duper happy with the engine.
 
One last issue I want to address:  Low idle is rough.  I suspect is mostly due to the my choice of cam because I don't have much vacuum at idle.  Cam manufacturer said as much.
 
I am wondering about one last option to tackle.  Crankcase pressurization.  There is zero smog stuff on the motor.  Not even a PCV valve.  Each valve cover has a breather cap.  What do you think?  Run a tube from one bank back to the air cleaner?

Butch Houghton

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Rough idle
« Reply #1 on: April 04, 2010, 05:04:52 AM »


You need a PCV also.   Breather in one side & PCV in the other.   You get correct flow that way for drawing the crankcase fumes out.

PCV to carb base & the breather to the aircleaner is fiine,

I forget, what were your cam specs?   Probably is just the cam.

Butch

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Stan Paralikis

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Rough idle
« Reply #2 on: April 04, 2010, 06:20:46 AM »

OK.  That's why I asked.  Why would not using them cause a rough idle? 

Steve

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Rough idle
« Reply #3 on: April 04, 2010, 07:44:09 AM »

Cause
 
It's taking the pressure out of the crankcase and burning the unburned gasses which enhance the idle combustion.
 
Sound good to me anyway
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Stan Paralikis

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Rough idle
« Reply #4 on: April 04, 2010, 09:07:46 AM »

Hmmmmm... 

Ken

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Rough idle
« Reply #5 on: April 04, 2010, 06:53:16 PM »

What der Benevolent Dictator sez.  Hook up a PCV system.

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Rough idle
« Reply #6 on: April 04, 2010, 07:24:31 PM »

Quite truthfully, surprised she idles good without the PCV setup, unless the carb butterflies themselves are opened greater to compensate for it, to which the carb usually ends up drinking gas because the butterflies are opened above the idle circuit and starts running on primary fuel circuit. This is where the little weight plug inside the PCV valve comes into play, so if idle drops the vavuum plugs the extra air coming in from the PCV and sucks a little more gas, and when it gets too high, it sucks the weight up and slows down the air coming in, so it does a balancing act of sucking internal vapors safely.
Breather in one valve cover up to either the side or bottom of the air cleaner with an elbow to allow fumes to float up and liquified oil to drain down the hose, and PCV in the other, but for both of them, if not stock, make sure there is a splash shield across the insides of the holes so regular splash doesn't transfer into the intake manifold or air cleaner in volume.
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Stan Paralikis

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« Reply #7 on: April 05, 2010, 06:12:13 AM »

Where is the best place to run the PCV tube from the cover?
The carb or the intake mani?

Steve

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« Reply #8 on: April 05, 2010, 06:21:06 AM »

There should be a nipple on the carb that will accept 3/8 hose.  Unless you have one of those. . .
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Stitcherbob

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Rough idle
« Reply #9 on: April 05, 2010, 06:23:22 AM »

a PCV is not supposed to hook up to the driver.......

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Stan Paralikis

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« Reply #10 on: April 05, 2010, 07:31:37 AM »

Done.  BIG difference! 
 

Steve

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« Reply #11 on: April 05, 2010, 07:33:51 AM »

You doubted us?  Shame
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Stan Paralikis

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« Reply #12 on: April 05, 2010, 08:23:40 AM »

Not for a second.  That's why I asked The Best & the Brightest.

Steve

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« Reply #13 on: April 05, 2010, 08:31:38 AM »

I won't take any credit for either of those catagories.  Not with Ed around.  Damned swabbie make me look like a mental midget
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Stan Paralikis

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« Reply #14 on: April 05, 2010, 09:59:33 AM »

Quote from: POLARACO
  Damned swabbie make me look like a mental midget
He usually loses me after the first sentence...
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