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I will get flamed on here for this , but I have always been a big believer in people over carbing street machines...

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13* initial with a xe284 isn't going to cut it. Add at least 5* and limit mechanical to get your total.

My guess, it's loading up because the throttle plates are open too far at idle.

Got more than one 360 with a xe268H running 750dp's with no problems. One gets 20mpg on the highway with 2.76-2.9x gears

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Throttle plates are not open to far at idle. Primarys have 1/8" breathers

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13* initial with a xe284 isn't going to cut it. Add at least 5* and limit mechanical to get your total.

My guess, it's loading up because the throttle plates are open too far at idle.

Got more than one 360 with a xe268H running 750dp's with no problems. One gets 20mpg on the highway with 2.76-2.9x gears

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Throttle plates are not open to far at idle. Primarys have 1/8" breathers

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You've got lots of good advice above, but I'm concerned with your response here. If you know how to check the relationship between the throttle plates and the transition slot at idle, that's fine. If you don't, I'll be more than happy to post a picture that illustrates it.

More than likely, after you follow the advice above and get the timing worked out, you'll be close.

As stated above, the idle and transition circuits can be leaned out if that's what it takes.

Minivan and Rapid Robert:

Regarding the overcarbing discussion, yes the factory put...what?...625 CFM carbs on 440HPs, and those factory engineers were no slouches.

OTOH, I was walking around the pits at Watkins Glen in the late 80's and came across a Firebird with a Buick V6 running a Dominator! The crew chief was in a talkative mood, so I obliged him with questions, the first being "Wassup with a Dommy on 250 cubic inch engine"? He said the Dominator worked out better for them, not because of quantity, but because it provided better quality (presumably better distribution...I don't know). If you followed the formulas, that V6 would have to turn stratospheric RPM - even assuming 100% VE, to work out to 1050 CFM.

Anyway, I never forgot that and think about it ocasionally.

We now return you to the rich 750 DP!

Jim

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Both primary and secondary trans slots look like little squares (not rectangles).
The primary plates have been drilled 1/8"

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You have to tune the idle circuit and I am not talking about the idle mixture screws here. There are innumerable books out there on how to tune a Holley, get one, read it, ask us questions till you understand it then buy a wideband O2 sensor and tune the Holley.

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Ordered How to Super Tune a Holley should be here friday. Should be a master buy Monday.

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Skep419, where are you at this point?

1 turn out on the idle mixture screws, and (I'm assuming) still a stinky idle? And since you only have 1 turn on the idle mixture screws, I'm assuming (again) that they're quite sensitive?

You might go beyond 16* initial timing just to see if the engine likes it. Don't hammer on it b/c you'll have too much timing at higher RPM, just putt around the block and see if it helps.

If the idle is still rich after that, it's time for larger Idle Air Bleeds and/or smaller Idle Feed Restrictions, as previous posters said. Long term, both of these mods require drilling and tapping on your carb. Short term, you can install a properly-sized wire in the IFR to partially block it. Shout back if you're interested, as there are plenty of people here who can walk you thought it.

Jim

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still stinks a little but I think I can live with it.

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We're Mopar guys, mon! We settle for nothing less than perfection!

Seriously, the wire trick is great because it allows folks to modify their carb without getting that queasy feeling that comes along with taking a drill to it. You probably already figured this out, but the downside is, once you've done all your pi R squared math and figured out the wire size to reduce the passage by 6%, you put the wire in just a few degrees off from parallel and all you math goes out the window, as the wire now has a larger footprint. It must, must, must be quare in the hole. I've seen people give up and just "live" with a badly tuned carb because the wire trick didn't work for them.

The better solution (if you have the stomach for it ) is to drill and tap the idle feed restriction (after carefully measuring it) to 6-32 and drilling a 6-32 X 1/8 set screw to the desired size and screwing it in. See pic.

The advantage is you bypass the kludginess of using wire.

All you doing is drilling out a pressed-in brass orfice, and slightly enlarging the hole beyond it, which is soft and easily drilled.

Anyway, it's something to consider. It's not a big deal, but I can certainly understand an unwillingness to attack a perfectly good carb with a drill!

Jim

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You might go beyond 16* initial timing just to see if the engine likes it. Don't hammer on it b/c you'll have too much timing at higher RPM, just putt around the block and see if it helps.

Jim

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The wire is in and it helped a little but now it pops out of the carb when I roll into the throttle. Doesnt skip a beet when I mash it. still likes the mixture screws no more than 1 turn out. Idles in gear between 3-5 vacuum, out of gear at 11 and cruise speeds at 15.

If I give it a accell pump shot while idling out of gear it bogs and dies. So it must still be way rich.

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