Car makes a loud poping noise at idle

[Quigs]

I just got done putting the engine back in my car and it runs but makes a loud poping noise at idle. I'm pretty sure it is getting to much gas because I can smell it. And at idle the block learn BL is at 150. But when I get on the gas and bring it passed 1,600rpms then it runs perfect and the BL is around 120 or 110 I can't remember. I'm wondering if a missing vaccum line or a vaccum leak could be causing the problem?? If not what else could it be?
Thanks
Phil

 

[mybuick]

might be a exhaust valve not seating properly. usually its because of a overheating or a long term miss. but you had the engine rebuilt, so i would of checked the valve seats to make sure they were making a good seal. to check this you will have to take the heads off and take the valves out, then get some valve lapping compound and put a little where the valve and the valve seat meet, install the valve with out the spring and using a lapping tool twist the valve so the compound makes a dull pattern on the valve and see if it has good contact with the seat. if not a valve job is in order to fix the problem.

 

[Quigs]

I rebuilt the heads rebuilt new valves, springs, ect. I just looked at it some more, I found a ground that I forgot to connect to the passenger side cylinder head. I'll connect it tomarrow and try again.