Just got my engine back from rebuilt shop everything new +30 flattop pistons crank 010/010 D3 heads everything new cam lifters valves springs timing chain you name it new. Got it into truck all new fluids filters spark plugs wires new rebuilt Holley 600.primed engine oil pumped up carb and started in one or two revulitions everything good oil pressure 75 psi no leaks. The problem won’t idle below 1500 /1800 rpms. Timing set 12 degrees btdc. Tried everything no vacuum leeks. Checked all the hoses good nothing unhooked. Runs like big vacuum leak ????? At my wits end. Any help appreciated thanks rick

 

I’m not a carb guy but I’ll interject since nobody else has yet. What block are you using? What compression roughly?

 

Also how much lift does the cam have?

 

it is a 1970 block bored 30 over has d3 heads mild cam compression ratio 10.0 -1. I swapped out the carb with holley 850 double pump and the engine ran / idled down great 500 /550 rpms. that 600 holley was bad. I wish I new what it is with that carb bad metering block ??? that carb was new and way out of warranty hate to junk it if it can be fixed

 

Sounds like idle circuit plugged up perhaps? I call em Helleys cuz they are a helley-lot-of-trouble!