Just a faster curve on the 14 advance with lighter springs will hold it off the stop so say idling in gear at 28 (so 9 mechanical advance in) with another 5 mechanical advance to go as rpm comes up.

without driving you can test how it will respond to more in gear idle advance by advancing it till you have 28 in gear and fiddle with idle see how it likes it I know this would be 42 total but at this point your not driving just finding a nice idle.

Then you tailor you advance springs to get it to idle at that advance but still have your 33 to 36 total.

I used to run 30 degrees in the dizzy with light springs so all in by 1200 rpm and most in by my 1100 idle with a bigger cam than yours. (or similar cam smaller motor)

I don't drive on the street any more and have a MSD with the 25 stop in light mopar springs advance is all in at my 1200 idle. basically I use advance for ease of starting.

Just a faster curve with lighter springs will hold it off the stop so say idling in gear at 28 (so 9 mechanical advance in) with another 5 mechanical advance to go as rpm comes up.

without driving you can test how it will respond to more in gear idle advance by advancing it till you have 28 in gear and fiddle with idle see how it likes it I know this would be 42 total but at this point your not driving just finding a nice idle.

Then you tailor you advance springs to get it to idle at that advance but still have your 33 to 36 total.

Dodgem:
Trying to wrap my head around this.... With the distributor at rest, the springs relaxed, your theoretical timing is lower at cranking..... but the light springs stretch once the engine fires they advance some, then you have another "stage" of advance?
Is this done by using a light spring on one weight and a heavy one on the other?

At present you may (probably) not getting any advance at idle just what you set to. It takes more RPM's to start stretching the stiff springs to get some of that 14 mechanical advance.

But put lighter springs in and idle rpm should be enough to allow some stretch and some mechanical advance. so say if you put the lightest springs in that came with your dizzy 950 rpm may allow dizzy to advance lets say 8 deg so that will give you 19 + 8 = 27 advance at 950 instead of it sitting at 19 total in both cases is still 33.

so one light spring may do it maybe needs too it's trial and error.

But as i said you can at idle turn dizzy till you get say 27 then mess with idle if it's good then tailor your advance springs to get you there after turning dizzy back to where it was.

Thanks, Dodgem.

I just drove the car after putting the air cleaner on. It was running PIG rich in gear! It was dropping in the 11.0 range but it was still pinging.
Huh?
I expected the addition of the air cleaner to richen it up some, but now it looks like I'll have to go back at least 4 jet sizes to get close.
I'm amazed though that it still pinged. I would think that an over-rich condition would have stopped that by a longshot.
I'm going to pull a plug and check the cranking compression. Before the cam swap, I was at 185-192. This cam has a later intake closing, so I really expected it to reduce cylinder pressure so it would NOT detonate given the same tune as with the '509 cam.

""It was running PIG rich in gear!""
On your next drive, after the engine is up to running temp, find a quiet parking spot and apply your emergency brake (or have a friend apply the brake) with the tranny in D. Then spend some time tuning your metering screws to achieve the highest vacuum reading while readjusting your idle after each adjustment (if needed). You should be able to tune it in D (13's or so) if you have enough initial timing.

"" It was dropping in the 11.0 range but it was still pinging.""
Was it pinging while showing 11.0 or did it ping under accel before it hit 11.0?

What was your leanest reading while you were out driving?

The closer I get, the further away I am.

Earlier I wrote that after the cleaning of the air bleeds and the UPjetting to #90 primaries, I was running waaay rich. It still pinged. I didn't run it to full throttle to see the A/F readings because of the pinging. It wasn't rattling nearly as bad as it has in the past, but it was there.
I came back and went back to the #88 jets. The A/F numbers leaned out a bit but it was still rich under load around 12.5 to 13.5. It still pinged as well.
The opinions I get on this brand of carburetor range from either guys with no comment to guys saying they are junk. Almost everyone that complained about them says they picked up speed and reliability with a Holley.
Tomorrow I'll put my 750 back on for a road test. If it still runs rich or detonates with this totally stock, UNmodified carb, I'll have to look elsewhere for the problem. I suspect that the Demon is a POS though. After I put in the #88 jets, the idle in Park A/F numbers really leaned out and the IN GEAR idling almost went full lean past 17.0. Its as if I am dancing around a goal that the carb isn't equipped to meet.

Oh, regarding RACE gas:
The entire point of changing to this cam was to achieve a later intake closing, reduce cylinder pressure and increase detonation resistance. Running race gas shouldn't be necessary. I checked one cylinders compression today and gor a 173 reading. That hole showed 188 with the 509 cam.

What ever is going on carb will normaly run very close to factory sets on just about any motor,
trying to over come high comression yet run reg cheapo gas is usaually a run at insanity at best,
1 has to either lower the compression or run at race sttings

At 173 cranking you should be able to run 91 with a good working carb.

I've been as high as 210 on 94 sunoco.

what is your stall speed.

If all else fails do a compression check on all 8?

jet that 750 up 2 or 3 sizes to make up for the 10% ethanol.

I ran some 110 leaded with the 509 cam setup. It ran fine with zero detonation. The thing is, a few years back, it ran fine on 91 with the same timing. Maybe some of that is due to the ethanol in the fuel, but I wonder if most lies in this carburetor.

Converter stall speed? Sorta hard to tell. Its a 9 3/4" unit that was built to be a 3000 stall. I didn't like the lazy way it felt so I had the builder cut it open and change a few parts inside. It stalls lower than that now.
When I'm stationary in gear holding the brake, it will start spinning the tires on concrete at around 2200 or so. Asphalt would probably be higher.

That's tight the tighter the stall the sooner the engine loads.

I'm not questioning you here, but, I don't know how...

I've got a 440 with a 484 that doesn't run for scat unless I spike it...

Compression is borderline...Six-Pack piston under a 452 head with a steel gasket...

I wish I had some good news here. I know that many members have chimed in trying to help.
The 750 made the engine idle much smoother. I was actually able to get it to idle down to 600 in gear without stalling. I wasn't able to do that with the 850 because below 700, it loped around and felt ready to stall.
The A/F numbers looked decent. Idle was in the 14.0 to 14.5 range and while sitting at a stoplight, it was in the 13.8 to 14.2 range. I was amazed at how docile the engine seemed. Part throttle A/F was just below 12.5 and no higher than 13.4, so that seemed within range.
It still detonated at 3/4 throttle and above. I even reset the timing to 17 initial and 31 total before the drive.
Everything that I have tried since the cam swap has resulted in detonation. Bigger jets, smaller jets. Bigger PVs, smaller ones. Different timing settings. Different distributors. A different carburetor. Different weather outside. Cool engine, warm engine. The only time it ran without spark knock was when I had the timing set to 6 initial and 20 total. That was only a test to assess things. I would never expect this engine to run right at that setting.
Currently, I am out of ideas.

does it do it if you run it up to 4000 then feed her some power??

don't know if this has been covered before, but are you sure it is detonation? maybe an exhaust leak? just throwing things out, but i guess you said it did go away with the retarded timing.

maybe it has more compression than you think? even with the new cam bleeding some of that off, it isn't enough?

don't know... i know comparing a hemi and a wedge isn't a real comparison, but i'm around 10.25-10.4:1, 210 psi hot cranking, and i have yet to hear the thing ping.

Did you ever check the fuel pressure under WOT? What spark plug are you using?

I agree here. I think with a 10.7:1 compression, you will have your work cut out for you to run this on pump gas...especially with the ethanol swill we have available today. Even with the aluminum heads, I think you are going to have a temperamental engine if you don't spike it with some race fuel. It's also possible maybe your compression ratio is a tad higher than you calculated.

The rule of thumb I hear is 9.5:1 max for iron heads and add a point for aluminum heads so you are a little past the border. I am sure somebody here will chime in that they run more than that on pump gas but every engine build is different. I agree with your logic on the cam choice but maybe not enough cam to bleed it all off?

If this were my motor, I would start with a head gasket change. I used the thick FelPro's on my build (.055" compressed) which helped bring my calculated compression down almost .2 points from the thin gaskets. With thinner gaskets (.039"), I would have been closer to a 10.6:1 which kind of made me worry about being in the same boat as you.

If the AF ratio isn't way lean @ WOT, then you really have two more things to try and fix here. Verify the engine is NOT running hot and/or lower the compression.

I would try to avoid retarding the timing any more than 31* total and that is too retarded in my opinion.

You will get there and your car will burn rubber (reliably) before you know it!