'72 1 barrel 1920...having a problem with the engine cutting out as soon as i let it idle down, revs up smooth, but will not idle or start without working the throttle to keep it going. brand new fuel filter, pump, and converted to electronic ignition with HEI so no ballast. about to go pressure test the pump. bought a cheepie clear filter and the trickle of fuel looked miserable, so i exchanged my new fuel pump for another new one. it started to get a flatspot off idle and it got worse and worse until now it won't even run..

Problem may be in the carburetor. Could be a clogged idle system or something more difficult to fix. Try this: rev the engine up ("tighten" the fast-idle adjust screw and put the fast idle cam up on as high a step as you can get it without significantly closing the choke), then remove the idle mixture adjustment needle (get ready to raise the engine speed by hand if it begins to stall when you do this) and spray a good brand of carburetor cleaner (I like Berryman's B12) into the hole where the idle adjust needle lives. Repeat a few times. Stop the engine.

Replace the idle needle, seat it LIGHTLY (don't reef on it or you'll spoil the carburetor!), back it out 2-1/2 turns, then turn it clockwise a half-turn and attempt to start the engine. If it starts, proceed from there to adjust the idle mixture properly. If it doesn't, go another turn counterclockwise and try from there. If no go, try TWO turns clockwise from there. If still no luck, you've got problems aside from a clogged idle system. Could be a vacuum leak at any of several places. Could be a bum PCV valve. Could be an internally-screwed-up carburetor.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

okay that worked somewhat, at least now it will idle, i had forgotten about old B12 chemtool, haven't touched that stuff since i was 7 years old in the garage making slot cars drive through burning puddles!

Sounds as if it's time for a carb rebuild or replacement!

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

yea, this is a fresh rebuild, i am in the process of trying to find a super six, no luck yet, but i am done with the 1920. it surges at idle and is just shaky in general,