edelbrock 1406 (600 cmf) running rich and driving me crazy - Third Generation F-Body Message Boards

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edelbrock 1406 (600 cmf) running rich and driving me crazy

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Old 06-19-2007, 02:09 AM   #1
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edelbrock 1406 (600 cmf) running rich and driving me crazy

here some spec. 350,stock 883 heads ( i think thats the numbers) with 2.02 intake and 1.60 eg. valves, Phoenix dizzy base timing at 8* mild cam i can't remember the exact numbers but it's nothing wild, vacuum runs at about 8 Hg.,
now it idling real rich, fouling the plugs, smelling bad, and getting black smoke out the tail pipes I've try putting different rods and jets in there it. it helped a little bit as i made it 6% leaner than base. i just put another set in there today which made it 12% leaner than base, but this change is messing with my power mode witch is running about where it should ( Little rich ).
now here's the weired part the only way i can get it to idle smooth is take both A/F screws out, as in out of the carb and in my hand out. but this gets the engine racing a little bit. also i can't really go by tack readings as there is some thing goofy with that too it's hitting about 7000 rpm at 40 mph in second gear (t5) and about 3000 in fifth at 55 mph.
tomorrow I'm going to try and put a different coil in there that i have laying around just to make sure it not that. and I'll see if the rod change helped. i started to change my oil and had to go, now it dark out and i have no garage . thanks in advance
also the carb has been striped and floats are correct there's probally some more info but my eyes are gettin heavy

Last edited by REDTAIL; 06-19-2007 at 02:30 AM.
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Old 06-20-2007, 12:12 AM   #2
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Re: edelbrock 1406 (600 cmf) running rich and driving me crazy

first off is the carb new? did you put a good fuel filter inline? the 2 screws in the front of the carb is for the idle mixture, screw them out to richen the mixture and in to lean it out, how it the accelerator pump rod, you may need to change it a little bit, i know i had to no my 350. sounds like it might need a rebuild, edelbrock carbs have to be very very clean, i have rebuilt mine on my 350 and followed a few steps on the edelbrock website and i couldnt be happier with it right now. runs pretty dang good, here is the site some pretty good vids.

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Old 06-20-2007, 04:50 AM   #3
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Re: edelbrock 1406 (600 cmf) running rich and driving me crazy

Your prob don't sound like the carb to me.

No "mild" cam engine should have just 8" hg of vac at idle. You should have in the 16" to 22" range. My 355 with a 272/284* cam has 18" HG vac at idle.

You have a vac leak somewhere.

Check all the ports/plugs on carb.. 3 on front, 1 on rear and 1 on rear pass side of intake. All vac ports must be used or capped/plugged off.

Next use a lenght of rubber hose placed to your ear and move other end around the engine. The hose will make small sounds louder. If you hear a hissing sound thats a vac leak.. Listen around where carb bolts to intake, around front and rear ends of intake, around sides of intake, around the vac hoses, power brake booster, etc.

Next your timing is too low. Set timing at idle with vac advance hose un hooked and plugged. Timing needs to be in the 14 to 16 degree range for any type of performance mods/use with older bowl shaped head chambers.

Here's why. Your Dist. gives around 20* of mech. advance. Total timing = mech. + timing at idle. Best power, throttle responce, mileage, best idle, etc comes at 34 to 38* total timing. so 20* mech. + your 8* = only 28* total.

What spark plugs are you useing? If bosch throw them away, they aint worth having. Use AC delco R45TS gapped to .045"

Next check your fuel pressure. Edelbrock carbs likes no more than 5.5 psi fuel pressure. I don't care what anyone even edelbrock says, these carbs starts to flood out with anything more than 5.5 PSI.. Also they run out of fuel on the top end with less than 5.0 psi. If you have more than 5.5 psi (which you probbly will) you will need to buy and install an adjustable fuel pressure reg. I like Holley's $23 one myself.

It ticks me off that Edelbrock don't put one in with every carb. 95% of the people will need an adjustable reg when using an eddy carb.

You said you have floats set right.. What are they set at.. The printed spec is wrong. From my 8 years of running nothing but edelbrock/carter afb carbs I can tell you the right spec is 7/16" at rest and 15/16" to 1" drop.. Checked with air horn gasket left in place, and height checked at very front tip of floats.

After you get the vac leak fixed, and your timing set.. Return the carb back to box stock rods/springs/jets or what ever you changed. Then go from there on your tuning.

Also when the vac leak is fixed it will run with the IMS screws in it (unless you have the idle speed screw adjusted out too much/too slow)

Now tune the idle mixture screws useing a vac gauge. Lighty seat both screws and back then both out 2 full rounds. Now set idle speed to 700 RPM.

Now hook up your vac gauge on a full vac port (driver side front). Turn 1 screw at a time as you watch the vac gauge. Try turning it in.. Look at vac gauge.. You want to turn screws to get the highest vac reading you can.. Might need to go in, might need to go out. Once you get the highest reading on that screw your idle speed will be alittler higher.. Adjust it back to 700 RPM. Now start tuning the other screw.. Same way. Look at vac gauge. Get the highest vac reading you can.
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Old 07-07-2007, 01:02 PM   #4
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Re: edelbrock 1406 (600 cmf) running rich and driving me crazy

not sure if your still having this problem but if idle is kind of erratic with hg that low im betting your valve lash is set way too tight...
i did the same thing on my new engine and it took me over a week to figure it out. with hyd lifters the best way is to run the engine 1qt low it will still get oil to the lifters but it wont shoot it at you. just back the rocker nuts out till it starts ticking then back in 1/2-3/4 of a turn.
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