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#5 and #8 lean cyl

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Old Jun 29, 2011 | 12:58 PM
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From: nashville tn
Default #5 and #8 lean cyl

I have two cylinders running lean, 327 hyd roller w/ performer intake, RPM heads and eldelbrock carb, pulled headers off and there is no carbon residue at all in the exhuast tubes for cylinder's 5 & 8 there clean as can be. I suspected a leaking intake manifold, double checked it for clearance and fit no problem and re-installed. This did not cure the problem. plugs are a light grey to brown,except 5&8 there a little more to the white side. compression ck's out from 1,3,7, @ 180psi 5,4,6, @165psi 2,8 @ 170psi , injected a little motor oil in low cyl's and all ran up to 185 psi. Engine runs good when warmed up but does have a strange mis prior to fully warming up around 3000 rpm- sounds simulair to a darn studder box at the strip. So I am stumped ?
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Old Jun 29, 2011 | 01:01 PM
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Originally Posted by dntoearthman
I have two cylinders running lean, 327 hyd roller w/ performer intake, RPM heads and eldelbrock carb, pulled headers off and there is no carbon residue at all in the exhuast tubes for cylinder's 5 & 8 there clean as can be. I suspected a leaking intake manifold, double checked it for clearance and fit no problem and re-installed. This did not cure the problem. plugs are a light grey to brown,except 5&8 there a little more to the white side. compression ck's out from 1,3,7, @ 180psi 5,4,6, @165psi 2,8 @ 170psi , injected a little motor oil in low cyl's and all ran up to 185 psi. Engine runs good when warmed up but does have a strange mis prior to fully warming up around 3000 rpm- sounds simulair to a darn studder box at the strip. So I am stumped ?
The 5-8 runner is where the vacuum is pulled from for accessories. You have a vacuum leak.
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Old Jun 29, 2011 | 03:43 PM
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Originally Posted by wombvette
The 5-8 runner is where the vacuum is pulled from for accessories. You have a vacuum leak.
Your a genius ! Thanks
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Old Jun 29, 2011 | 11:06 PM
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From: New Hill NC
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Originally Posted by dntoearthman
Your a genius ! Thanks
No, just a lot of experience.
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Old Jun 29, 2011 | 11:12 PM
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From: Oxford MA-----You just lost the game!!!!
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Originally Posted by wombvette
No, just a lot of experience.

Don't be modest, you're a genius.

Scott
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Old Jul 5, 2011 | 08:14 AM
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Originally Posted by wombvette
No, just a lot of experience.
Hi wombavette,
I would love to pick at your experience if you don't mind. My 79's (AC car) Is always blowing HOT at the feet or up above if set that way, the slides are set at the coldest setting. It seems to be worst when driving, worst even with one window open and most worst when both windows are open. This is heat that roast my feet. Any suggestions?
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Old Jul 5, 2011 | 09:41 AM
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From: New Hill NC
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Originally Posted by silver79
Hi wombavette,
I would love to pick at your experience if you don't mind. My 79's (AC car) Is always blowing HOT at the feet or up above if set that way, the slides are set at the coldest setting. It seems to be worst when driving, worst even with one window open and most worst when both windows are open. This is heat that roast my feet. Any suggestions?
There are a few things that traditionally cause problems in those years. First is the vacuum control on the switch under the console. That controls the air distribution up and down through the dash. The temp slider controls the flap that allows the air to go through the heater core, and on some, a valve under the RH dash that controls the water valve under the hood. One thing often over looked on these cars is the flap out under the RH fender, behind the screen in the wiper well. It controls the outside air intake. It should close off the outside air when the ac is turned to max. Factory assembly procedures often pinched the line going to it or excess bond materials stopped it from working.

So in short, you have to control the air distribution, the hot water, and the intake air.

That will give you a start.
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Old Jul 7, 2011 | 11:24 AM
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From: d.d.o quebec
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Originally Posted by silver79
Hi wombavette,
I would love to pick at your experience if you don't mind. My 79's (AC car) Is always blowing HOT at the feet or up above if set that way, the slides are set at the coldest setting. It seems to be worst when driving, worst even with one window open and most worst when both windows are open. This is heat that roast my feet. Any suggestions?
One thing often over looked on these cars is the flap out under the RH fender, behind the screen in the wiper well.....Do mean the mesh outside the car? where the wipers sit?
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Old Jul 7, 2011 | 01:38 PM
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From: New Hill NC
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Originally Posted by silver79
One thing often over looked on these cars is the flap out under the RH fender, behind the screen in the wiper well.....Do mean the mesh outside the car? where the wipers sit?
Not necessarily the mesh itself. On the RH side behind that mesh down in the cowl, there is a flap that opens and closes.
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