Carb Backfire with oil??

[mbenito]

Hey guys,about 6 months ago I bought a 1969 Coronet 318 petty much stock motor. This car was made in México by Automex so it has a 4 bbl manifold instead of a 2bbl and the camshaft is pretty much the one from the 360. The guy I bought it from had a 2bbl carb installed with an adapter.
Anyway, I had just replaced a lot of the electric components in the engine bay including alternator, starter motor, battery, voltage regulator and ignition coil, new spark plugs and oil changed recently; and now the car backfires though the carb (specially when cold) and its spitting oil on the hood and everything else.

Vaccum reading is a bit low (8-10 psi on idle)
No visible vacuum leaks
Compression seems fine on all cylinders
It didn´t backfire before the electrical replacements.



What could be causing these issues?

 

[67 coronet]

recheck firing order and timing first.

 

[69Bee]

The oil is coming from the dipstick, and not the carb. The low vacuum is likely due to the motor being worn, and the rings are allowing quite a bit of blow-by. The PVC system is either clogged, or overwhelmed by the blow-by, so it is being blown out of the dipstick tube, and the fan then blows it all over the hood.

 

[Warpspeed]

Yeah, had that oil out of the dipstick prkblem because I didn't have a vented valve cover on one side. Timing needs checking to stop backfire (obviously after making sure plug wires are on correctly).