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Old 05-17-2013, 04:27 PM
bygddy bygddy is offline
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Originally Posted by F-BIRD'88 View Post
By "too rich" I'm saying it makes your eyes water anywhere near the back of the car, and very very minor dark smoke at idle at the tailpipe.

Yes I nknow I need a wideband but can't make that happen until next month.


This does not indicate a "rich" idle. What it indicates is raw unburned fuel in the exhaust.
Poor combustion at idle. Misfire... late combustion.
If the idle screws are active like you say then the idle circuit is not too rich.

But the combustion is not complete. One or more cylinders are misfireing at idle
one or more cylidners getting a different afr mix at idle (leaner,,,,vacuum leak.)
manifold plenum too cold. poor fuel mix/vapourization... fuel pudding in the manifold. Cold...
late spark advance at idle. Ignition system fault causing missfire... cross fire spark scatter. cap coil rotor wires
leak in the header gasket at the head.
all these will throw off idle idle. leaky valve. liquid fuel will not burn. poor fuel mix (there is enough fuel but it is not mixed well-evenly to all 8 or vapourized well)

A simple heated narrow band will do 98% of the job for you, for peanuts.
A wide band is nice but the simple home built NB gets it done.

Blue smoke burning oil
black smoke misfire
white smoke water leak, cold engine, water vapour, water in exhaust
white smoke trans fluid burning.

You cannot smell a "rich" or a lean air fuel mixture.
A stinky exhaust/burning eyes is incomplete poor combustion....
start with the ignition system.
Do not idle or try to tune you car in the garage, even with the door open.
Take it outside.

check for a header gasket leak. check for correct throttle position at idle.
check condition of the igntion system "new" is always suspect.
Possible rotor cap phasing alignment issue Scatter/misfire
do a simple cylinder balance test to find the weak cylinder(s)

Again : look at the idle air bleeds on the old stock donor holley carb body.
What size are they? pri/sec.

OK, so ignition is "new" and worked before my changes, its actually not as bad as I thought, yes its smelly, but black smoke when rolling and getting into the seconadties. Plugs look dark and rich, idle isnt as bad as I thought and I will measure the old bleeds when i get something to measure with. I changed plugs just now, and jetted down a touch, it was 72/80, I'm now 68/76 and going to go drive, pull plugs and see what it looks like. Miss fires are not present, it idles calm and smooth with no stumbles. Ground is something that got my attention tho now that u mention it. It was grounded at the cast heads and I did reinstall the same ground on the alum head. Now I wonder if its not sufficient.
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