Another edelbrock carb question!

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dartkory

dartkory

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So I have a 1405 that I feel I finally got pretty close to perfect when cruising and flooring it. But it still burns rich at idle, which makes it begin to eventually build up when sitting in traffic for a while, then blows black smoke the first time I floor it but doesn't blow any smoke the second, third, etc. before anyone asks, I have the calibration kit and jetted it down so far that it would just stumble and still burn rich, and I tried messing with different squirters and so I'm beginning to think it may be my floats. Right now they are set at spec. If I want the needle to close sooner would I need to adjust the float down? And right now I have the weakest step up springs in which helped a lot but obviously it still seems to not be pulling the rod down all the way so should I hook my vacuum advance to the full time vacuum port as edelbrock suggests? Thanks for any help! -Kory
 
Are the throttle plates closed enough that the carb is idling off the idle circuit? Check the fuel pressure. Eddys like no more the 6.5 psi
 
What is your idle rpm? What is the vacuum reading at idle, in gear?
 
Idle rpm is about 700 and vacuum in gear is 7" and 1973dusterkid, I originally had a 1406 edelbrock and went to the 670 avenger and couldn't believe the difference but it burned rich all around no matter how much I tried to tune it then I went to the 1405 which is calibrated for performance compared to the 1406 and was even more impressed over the holley. Plus I was always needing to mess with the holley I just want something I can set and forget.
 
Have you ever sorted out your initial timing issues?

Is this the 318 with the xe268H or voodoo cam in it?
 
Yes I got my timing all figured out and set. It's 16 initial and 32 total. And my 318 has a comp 275DEH cam in it
 
Glad to see someone else you doesn't think that the sun rises and sets on Holley. They are a great race carb but in my opinion the eddy is a better street carb!
 
So is there fuel dripping from the boosters at idle? That idle vacuum is pretty low you might need more initial timing... What's the compression?
 
IMO, not enough initial with that cam in a 318. Do the starter kickback method to set initial and see how it idles after adjustment.

Fuel pressure would be the other area I'd look into, max 5 psi with that carb. I'd check this first.

Vacuum is VERY low in gear. How much does rpm drop going from P to in gear?

I just saw a 360 with the same cam, idle in park, it pulled 13" at 850-900rpm.
 
What do you mean by starter kickback method? My RPM drops about 200 going from park. And I don't see any fuel dripping from the boosters. Compression is about 9.5:1
 
When warmed up, add 2* to idle timing, reset your idle rpm, shut it off, try to restart it. Do this until you find the point that the starter drags bad or kickback. Once you find that point, back it off 2* and lock it down. That's where you can run initial at the max level.
 
Depending on your starter circuit it might be as high as 25°. Is it a stock convertor?
 
Honestly - I'd expect no drop in rpm when put in gear with a higher stall at 900rpm. I would suggest re-tuning. I think it's lean. Too lean causes the same issues as too rich, except it tends to lose rpm when it's put into gear. It will always have a fuel smell at idle because of the large cam. So getting a perfectly clean idle isn't possible. Holleys like 1 1/2 turns out - I've had Carter/Edelbrocks that like more -2, 2 1/2 to clean up. So my advice is add another 2-4° of initial, reset idle speed to 750-800, reset the idle mix to highest vacuum level in park, then go out another 1/4 turn. A lot of tuning is by feel but that's where I'd be playing around at.
 
Thanks for the advice I'm gonna do just that when I get home. This might be a dumb question but I'm a little confused. So does the primaries have anything to do with the richness/leanness at idle?
 
Too much secondary blade opening?

IIRC, you've had 3 carbs on this thing and they all act the same, ever think that it's not the carb?

Set initial CORRECTLY and it just might clear up the issue. Picking a number out of thin air IS NOT getting it done right, IMO.

The 360 had 16* initial and I thought it might be a little light, BUT, that was the limit of the tuning tools available. A likely lower compression 318 with the same cam, no idea if degreed, isn't going run at the same initial.

Good luck with it.
 
The primaries are the only throttle bores that have mixture adjustment screws. So the primaries are the only source of idle speed/quality. If the carb is working and set right. The secondaries on the Edelbrocks should be totally closed at idle.
Also - as I said - it will never idle without a raw fuel smell because of the cam/engine combo. So if that is what you're chasing, you're chasing your tail.
 
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