Running too rich... please help

[Peter82]

My truck is running too rich... My buddie said that the carb can be adjusted by the front 2 screws to lean out the mixture but he didnt remember how to do it. He said something about screwing them both in all the way and back them out like 4 times. Any one know the real adjustments???

[High Speed low Drag]

Screw both all the way in. Back them both out about 2 1/2 turns. That should get you in the ball park. Play with it from there.

[corn]

When you turn them in, just seat them. Dont ever tighten an idle mixture screw. Ive always started at 1 1/2 turns out but Im used to Holley's...

[67ChevyRedneck]

^Do you mean don't ever "over"tighten an idle mixture screw?

[corn]

Yep, exactly. When it stops, quit. The mixture screw has a sharp point on it that seats when closed. If you get carried away screwing it in, you will end up screwing it up.

[67ChevyRedneck]

Never knew that. I was always "gentle" with mine

I think I have mine set at 1 3/4 and my truck runs good. My timing is also set to 12 deg btdc.

[ChevLoRay]

"Screwing it up" for these adjusters happens when you turn them and bottom them out. When it happens over and over, or if it is done with enough force, i.e., screwing them until you can't possibly turn them anymore, the result is that there will be these nice little grooves that go all the way around the pointed end of the adjusting screw. The resulting action is that you can't ever get the idle air adjusted because the air goes to the point of least resistance, and that groove is a permanent place for the air to go.


Just turn them until they barely stop turning. Then, back them out. I always did 2 turns on a Rochester.

But I see you have an Edelbrock. If it is an 1406, with a manual choke, it is jetted from the factory with .100 main jets. It will be rich. There are other jets that you can get, so that may be the way you have to go. Look at www.edelbrock.com and find the carb tech section. It will give you a lot of info that may be of help.

[jkade]

I would say get used to it with that edelbroke unless you change jets

[Peter82]

Thanks guys... i am going to check out the web site first and if they dont give me what i am looking for i will try and adjust them... i am so glad you guys know so much about these trucks. i dont know crap about them. thanks

[72armyswbtruck]

Give yourself some credit now you know how to adjust the airflow fuel mixture on the edelbrock carb...

[tx71smallblock]

the manuel for mine says to tighten one untill the motor starts to sputter then back out about a half to a full turn, then do the other the same way. but it also says that these have nothing to do with the running mixture just the mix at idle.

[tx71smallblock]

i also noticed u dont have ur pcv valve hooked up, why is that?

[blukangoo]

I´m going to start mine today for the first time after the restoration.
It was running rich before too. It has a 1407 (750 CFM) on a 327.
Way too big for the engine but don´t have the money for a different one.
Our mechanic said see what it does after the restoration and maybe we can change the needles to step it down a little.
Thanks for the infos on the Idle screws. I will try that.

[Peter82]

Originally Posted by tx71smallblock

i also noticed u dont have ur pcv valve hooked up, why is that?

Yea... i got the truck for $750 and all i did was change the spark plugs and add a new battery, add some tranny fluid, change the oil and the diff fluid. i really dont have any idea where stuff goes and what is really missing. i will be ripping the engin out next spring and re-do everything. what will the PCV valve do for me?

[blukangoo]

Originally Posted by Peter82

what will the PCV valve do for me?

The Positive Crankcase Ventilation valve, or PCV valve, is a one-way valve that ensures continual refreshment of the air inside a gasoline internal combustion engine's crankcase.

[GREASEMONKEY72]

PCV valve sucks in the unburned fumes and different gasses out of the crankcase and reburns them, basically its an emissions deal and ive heard you get better mpg with it hooked up

[brak]

Here's a little known fact: PCV was actually invented back during WWII for use on tanks, to keep water out of the crankcase.

Here's my favorite definition:
As an engine runs, gases from the cylinders leak past the piston's sealing rings into the crankcase (containing the crankshaft and other parts). This leaked gas is sometimes referred to as "blow by" because the pressure within the cylinders "blows" them "by" the piston rings. These gases include compounds harmful to an engine, particularly hydrocarbons (unburned fuel), as well as carbon dioxide and water vapor. If allowed to remain in the crankcase, or become too concentrated, the harmful compounds will condense out of the air within the crankcase and form corrosive acids and sludge on the engine's interior surfaces. This can harm the engine as it tends to clog small inner passages, causing overheating, poor lubrication, and high emissions levels. To keep the crankcase air as clean as possible, some sort of ventilation system must be present.

[jkade]

I would say that you really need a vaccum guage to adjust the carb the right way. I may be wrong

[cdowns]

alot of good advise for adjusting carbs

my questions are what makes you think its running rich?? what do your sparkplugs look like?? what does the exhaust look like and smell like??

you just gotta love that rubber fuel line runnin right near the exhaust manifold KABOOM

[neonlarry]

If its RUNNING rich adjusting those screws are not going to help you any. Those are idle mixture screws, if its ideling rich adjusting those will help. But they won't do a thing for anything off idle. That will have to be done like said above by changing jets etc.
And yes, get rid of that rubber fuel line.

[tx71smallblock]

although advised, u dont have to get rid of the rubber fuel line. u can just reroute it in a better position with an edelbrock "banjo" fitting for the fuel inlet on the carb.

[Peter82]

Originally Posted by cdowns

what does the exhaust look like and smell like??

you just gotta love that rubber fuel line runnin right near the exhaust manifold KABOOM

well the exhaust looks kind of black and it smells like sweet candy... it smells rich. you know, like rich exhaust fumes.

that fule line dosnt really run right near the manifold... it just looks like it. but is what you guys didnt really see is that i have a glass fuel filter... yea, i need a new one.
Thanks for the help guys.

[ChevLoRay]

When I replaced my Edelbrock 1406 (manual choke), which was running rich, with an Edelbrock 1901 (I think that's the number), the down side quickly became the hard starting when hot. After putting a heat shield on the starter solenoid, no problems. The rich-running carb was being seen in gas-fouled spark plugs and popping in the exhaust. Oh, that and the acrid smell that burned your eyes. But the richer mixture is cooler and that is why the new carb caused the heat soak problem.

So be aware that leaning-out the carb by re-jetting it and changing the metering rods may cause a hot-start problem.