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#2452103 - 02/15/18 10:26 AM Re: 6 pack metering block question [Re: BSB67]
Twostick Offline
master

Registered: 05/20/03
Posts: 5005
Loc: Downtown Roebuck Ont
Originally Posted By BSB67
Originally Posted By mickm
I have it farther down, in the 14+ range, just turns the screws farther out.

I'm just going to live with it. There are other things that need attention, this is just more of a nuisance than anything else.

I didn't expect it to take this much time and energy, but since it is what it is and doesn't harm anything, it's good enough.


If you have a large overlap cam you should be focusing on idle quality, not what an O2 meter is reading. It simply does not read right. If the O2 meter is reading 15:1 the the combustion charge AF ratio could still be far too rich. Some have reported as high as 18:1 meter reading at best idle quality w a big cam


iagree

Make it idle happy. The AFR will land where it lands.

Every time it misfires, all the O2 that didn't get used for combustion goes out the exhaust and a big overlap cam misfires A LOT at idle. That's why an engine idling pig rich can indicate 18:1 dead lean.

Kevin

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#2452116 - 02/15/18 10:59 AM Re: 6 pack metering block question [Re: Twostick]
jbc426 Offline
master

Registered: 03/01/07
Posts: 2789
Loc: West Coast, USA
My FAST portable wideband wouldn't even read my air-fuel ratio at idle. It's beyond it's range, because its too rich. I changed my cam and compression, and am a day or two away from seeing if it will read it with this one.
_________________________
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 3.73s
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 3.91's (closest thing to an automatic 5 speed going)

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#2452125 - 02/15/18 11:19 AM Re: 6 pack metering block question [Re: mickm]
krautrock Offline
top fuel

Registered: 01/27/03
Posts: 1766
Loc: central texas
Is everyone setting idle mix by adjusting to highest idle speed or vacuum reading?

after I threaded the IFR's in my metering blocks and dropped the IFR size down, I figured I would be close to the typical 1.5 turns out from seated so I set them up initially at 1.25 turns out.
It started and idled OK, kinda bumpy, kinda stinky.

after it warmed up all the way I started leaning them out, idle goes up, smooths out. keep going around the carb, a tad leaner every time. Ended up at just a touch more than a half turn out.

I was thinking wth, after all this work these should be further out, then I figured well, I dropped the IFR down but the I didn't touch the idle bleeds and they are roughly .067", pretty small.

The idle smoothed out, smells much cleaner (still smells like it has some overlap), I had close the blades to drop the idle back down...it starts up with just a touch of the key when it's warmed up...I'm just gonna worry about other things now and leave the idle screws where the motor likes them.

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#2452233 - 02/15/18 02:35 PM Re: 6 pack metering block question [Re: Twostick]
mickm Offline
master

Registered: 07/26/06
Posts: 4080
Loc: California
Originally Posted By Twostick
Originally Posted By BSB67
Originally Posted By mickm
I have it farther down, in the 14+ range, just turns the screws farther out.

I'm just going to live with it. There are other things that need attention, this is just more of a nuisance than anything else.

I didn't expect it to take this much time and energy, but since it is what it is and doesn't harm anything, it's good enough.


If you have a large overlap cam you should be focusing on idle quality, not what an O2 meter is reading. It simply does not read right. If the O2 meter is reading 15:1 the the combustion charge AF ratio could still be far too rich. Some have reported as high as 18:1 meter reading at best idle quality w a big cam


iagree

Make it idle happy. The AFR will land where it lands.

Every time it misfires, all the O2 that didn't get used for combustion goes out the exhaust and a big overlap cam misfires A LOT at idle. That's why an engine idling pig rich can indicate 18:1 dead lean.

Kevin



Yeah, got it. I usually do it with a vacuum gauge. Will start again there and see where it ends up.
_________________________


"the orange fun car" 540 Hemi 4 spd 3:54 dana
1 of 1 - only FK5 70 Road Runner that used to be a 383 auto now a 540 Hemi Six-Pak 4 spd in existence

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#2452425 - 02/15/18 11:33 PM Re: 6 pack metering block question [Re: mickm]
mickm Offline
master

Registered: 07/26/06
Posts: 4080
Loc: California
Cam is 248/255, .604/.582 LSA 112 on a 110 centerline.

That doesn't seem big enough to be the cause of my idle stink!
_________________________


"the orange fun car" 540 Hemi 4 spd 3:54 dana
1 of 1 - only FK5 70 Road Runner that used to be a 383 auto now a 540 Hemi Six-Pak 4 spd in existence

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