ive got a 1974 dodge tioga motorhome.318 with a holley 2 bbl.i had carb rebuilt,new plugs gap is right,new wires,new coil,new voltage reg.,new dist with electronic ign.replaced all the rubber fuel hoses.all other vaccum hoses in good shape.replaced both fuel filters.getting good spray into carb.air fuel mixture screws 2 turns out from seat.its surging/missing so bad when i put timing lite on it the timing mark is floating back and forth cant really set it.when i ease the gas on it really surges/misses it wont idle smoothly.made sure plug wires were spread out.plug wires are correct.sprayed carb cleaner around intake manifold around carb hell all over the engine no change.engine has never been soooo clean.my dad passed away and i got the motorhome i dont have anyone to ask if it was running bad before.put new gas in with a can of heet treatment.I JUST DONT GET IT!!!!!!......gentlemen please help

 

Timing floating back and forth could be loose timing chain or worn oil pump distributor drive, if you are timing with vacuum advance disconnected and plugged.

 

its not idling smooth enough to accurately set the timing.i set the dist. where it idles the best.there is no egr valve on it.the oil pump gear looked good

 

The timing should not be jumping around !! MAKE sure you have the vacuum advance disconnected. Then re check If it is still jumping ?? Even a loose chain should hold a steady timing mark.. would take the dist apart and check the springs in the advance

 

Was it surging before you put the new distributor in? The width of the slot on the distributor shaft, if too narrow, will have play in the shaft drive and give varying timing results. I heard this has been a problem for some with new distributors.

 

Put a vacuum gauge on the intake manifold, disconnect distributor vacuum and plug off. turn carb mixing screws, and rotate distributor to get the most vacuum. All engines run differently and turning the mixing screws out 2 turns is just a staring point. You will have to work between carb and distributor to get 18-20 psi of vacuum in a stock engine.