I finally got my freshly built 355 installed.
The break in procedure went perfect. Started right up, ran at 2000-2500 RPM for 30 minutes, changed oil, ect. But now I can't get it to idle below 1500. When I do it just bogs down and sppits a white cloud of smaoke and fuel mist from the carb. I was running a new Holley 750, and tried a known good Holley 600 with the same results. I checked for obvious vacuum leaks, plugged up all vacuum ports on carb and intake.
It sounds great above 1500. I have about 16 inches of vacuum at 1500. The engine again is a 355 with 10:1 compression, Trick flow heads, headers, Holley 600 (now). Accel Billet distributor. AC Rapid Fire Plugs no. 5, Crane Energizer 278 cam (222/222 duration 467/467 lift) Comp magnum roller tip rockers, performer RPM intake.

Any suggestions appreciated.

Mike

Sounds like the timing is too low or the timing marks on the cam gear and crank gear are not lined up properly. Try turning up the timing first. At 1500 rpm a timing light won't help, you have to get the idle low enough so that the weights in the distributor are not advancing to use the timing light.

That's what I was thinking - ignition timing. Just advance the timing until the engine will idle down. Once it idles down set the timing with the light.

Valve adjustment could be too tight if you have a hydraulic cam, but it probably wouldn't effect your idle THAT much.

You could also have a fuel system problem, like a fuel pump that is starting to go out but that is less likely.

I dropped the distributor in at TDC pointing the rotor to no.1. I advanced the timimg till the vacuum housing is touching the manifold, doesn't really help. At that point the engine is so far advanced it struggles to turn over if I try to start it from that point. The shortblock was assembled by a very experienced engine builder, he claims he degreed the cam, but could he have accidently installed the cam wrong? Again it sounds great above 1500.

Thnaks for the help,
Mike