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Stupid question but I assume the vaccuum advance advances full under heavy throttle. I tend to burble under even load, runs strong under heavy throttle. Can I assume the spark is slightly retarded???

No. The vacuum advance advances under light throttle. This "burble" can be caused by too spark advanced too much.

don't know what burble is....if to far advanced it will make a pinging noise under throttle...

I posted this link about vacuum advance the other day:
http://www.classicchevytrucks.20m.com/vacuum.htm

To answer your question directly, there should be zero vaccum advance at heavy or full throttle.

I think we need a better definition of "burble." If you mean that the engine stumbles and misses at part throttle, it could be "lean misfire" caused by the primary jets (or what have you) being too lean. If it just happens when you apply part throttle, then it might be corrected with an accelerator pump adjustment or replacement.

Another thing to check would be your static timing (at idle with the vacuum advance hose disconnected) and then the dynamic timing by running the motor up to around 3000 rpm (all cnetrigugal timing should be in by then.) A dial-back timing light would be helpful with this.

make sure the vac advance is working. i have seen many of these with split rotted diafrms that did not advance. Ray's timing post will show you this.

Well everything is quite new. you think i am running to lean. the burble is a slight miss under normal throttle at 45-60, heavy acceleration takes it away pulls stong as far as I dare take it. 90+

I'd check your ignition system (wires, cap, rotor, coil) and plugs (read them), but I, too, think you may be slightly too far advanced.

I'd do one or two things. I'd check the static and dynamic timing. If this doesn't solve the problem, then I'd put in the next richer set of jets or metering rods in the primaries. One way or another, I'd think that otta help out.

Ray, Like your advice best(others said the same thing) Will redo the timing today, if that doesnt work go to jetting. will figure out how to do a Edelbrock later. Thanks to all

Changing the metering rods in an Edelbrock carb is WAY simple. Ya don't even have to pull the airhorn. Just remove the small cover from the top and pull the rods out. Drop the new ones in and replace the cover.

The only thing ya gotta have is some different sized rods. I bought a tuning kit for my carbs. It cost about $70, iirc. But there are 3 sets of jets and rods, different secondary springs and some other stuff. I got mine at OtterZone, but I dunno if they still carry 'em.

Good luck with it,

Well, sorta confused, don't want to spend 70 unnessarily on metering rods.. This is one of those "was running great when I parked it" thing. (last fall) aren't the needle jets on the bottom only Idle mixture
adustments?

The adjustments on the front of the carb are for idle mixture only. But on the TOP of the carb are small covers that allow the replacement of the metering rods.

Well, check the timing and let us know what you find. If you feel so inclined, take the airhorn off the carb and see if there's any dirt in the bowls. Also check for vacuum leaks such as cracked hoses or loose connections.

But there's no way you're going to go to the next smaller set of jets unless you buy them (and with the tuning kit you get the metering rods, too.) Runnin a hot rod ain't free.

On that timing issue you'll also want to make sure the mechanical advance is working properly as well. You may have weak springs or incorrect weights.

Have replaced wires, plugs, weights/springs last year. Will check vacuum lines. mechanical advance appears to be working ok. (no points or condenser) It almost seems it has to be timing or vac. ad. That's the only thing i have screwed with this year and it was fine last fall.