I have it all in by 2,500 rpms. 32 degrees. Not running a vacuum advance. So base and mechanical all in around 2,500.

check the timing at idle that will give you the initial - I run on my street car 24 at idle and all in at 2000 RPM at a total of 34 really helped with the stumble and cleaned up the bottom end

have you checked your distributor for sticking weights or advance plate ?
some of the ready to run units i have seen have little to no lube [they don't need much, but a "little dab 'll do ya"] and will sometimes start to rust a tiny bit, causing stickyness.

To easy. All good there working as it should.

I've always run NGK R5671A-8 (4554) plugs in my pump gas hemi when running it naturally aspirated. I would think an R5671A-7 (4091) would be fine for yours.

I drained the tank and kept samples. Old fuel like a light whisky color. New fuel clear like moonshine. Raining so no test drive. I did start it and maybe it is in my head but it seems to feel and sound better. I do not think it will cure everything but I wont know till I drive it. After that it will be plugs.

What did you replace it with, same stuff just fresh/summer blend? Or did you change brands/types?

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What did you replace it with, same stuff just fresh/summer blend? Or did you change brands/types?
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Different brand Shell v-Power premium 100 octane. Not much to choose from in my small area. I would assume it is a summer blend.

100 octane I would assume that a seasonal thing? Around here we get 100 but it's only available in the summer.

My bad in a hurry. 100 percent ethanol free 91 octane is what I ment to say. Drove car today and it is running a lot better. That gas was junk. At least now I can work on fine tuning it. I think that I need some adjustment. Driving a cammed big inch Hemi with a carb is a lost art. Diesels and EFI behind a stick have better manners. So some will be me adjusting and the small changes I make should be noticeable. The way it was running there was to much wrong at once. Hard to believe that I put 19 gallons of premium junk in it.

A long time ago I used to drive my charger to the track and race it, I would always stop at a local station that sold Turbo Blue. It was the same tank as they sold kerosene in the winter. Well I was there early in the year and they must not have cleaned the tank out and I got a lot of ribs in the staging lanes because of the smell from my car, smelled like I was racing an oil furnace.

That v-power fuel is real good stuff. Used to use nothing but, til all the shell stations were taken over by BP here in lower MI. It has the smell of race fuel as it burns. I run a 6 heat range plug in my 12.5:1 511. I would get a fresh set of 6 or 7's projected tip plugs and get them in there as others have suggested. You say 10" of vacuum. Is that in drive idling? What duration at 50 and lobe sep on that cam? Dom@Thumpercarbs could get that carb right for you as he has fixed a bunch of ProSystem carbs. I ran one of Dom's 1100 Dominators on my street/strip 511 and you wouldn't believe how clean it ran and never a hiccup on accell.

That was my thought also that the color could of been a winter blend like you said or a truck load accidentally mis-blended fuel. I have a friend that drives tanker for Klem and he said it is all pre-determined when he loads. So who knows. This was a first of this for me. We will see if the lawn mowers will run on it. If not to the burn pit in the fall at camp.

wonder if because it's kind of a specialty gas that it was old at the time of buying...they probably don't sell much ethanol free over the winter and you got some of last summers batch.

This place moves a lot of fuel. Re-looking at my parts receipts I got my fuel sender calibration box around April 10th. So my first buy would of been around then for the low side calibration. And the rest within a day or so for the high end calibration. So who knows. For now I am happy with how it changed the running. As soon as you said like fuel boiling the steam out of the vent became a vivid picture. I have samples in clear glass bottles I will try to get a picture of.